Posts Tagged ‘strawberry’

Strawberry IPM Newsletter No. 6 – July 11, 2017

Tuesday, July 11th, 2017

StrawberriesStrawberry IPM Newsletter No. 6 – July 11, 2017
Click on photos to enlarge.

RENOVATION AND WEED MANAGEMENT ISSUE

Get Your Strawberry Beds Ready for Next Year

Manage Pests in Day-Neutral Strawberries

Not a bad winter, by Maine standards, but some fields did show a small amount of winter injury this spring. The extremely dry summer also took its toll as many beds had thinner plant populations than normal this spring, due to a lack of good runner growth last summer. An extended cool spring delayed early plant and flower development, leading to a later ripening crop. Many PYO fields opened five to fifteen days later than normal this year. Pest pressure was relatively light in most fields. Spider mites were the most common problem across the state, although some fields had more serious problems with strawberry bud weevil or “clipper”. Disease pressure was also light in most fields, with leaf spot being the most common problem. Because of the rain, many fields needed at least one extra fungicide treatment to keep gray mold to a minimum. All in all, the harvest was pretty good, with quantity and quality very good, and berry size down a bit, likely due to last year’s drought during flower bud formation.

Now that harvest is coming to an end, don’t forget about your strawberry plants. Renovation of your beds should begin soon after harvest to allow as much time as possible for the plants to re-establish and form lots of healthy flower buds for next year. Follow the recommended renovation steps listed below for matted row strawberries. Continue to scout for and manage disease, insect and weed problems as they arise. Some of the more common issues to be alert for during the summer are listed below.

DISEASES
Foliar diseases should be monitored in your fields by regularly examining leaves. Foliar diseases are more likely to become apparent under wet weather conditions. The most common summer diseases are powdery mildew, leaf spot and leaf scorch. Fungicides available for these diseases include captan, Topsin-M®, Cabrio®, and Pristine®. See the New England Small Fruit Management Guide for detailed descriptions of these diseases and their management.

Powdery Mildew

Powdery Mildew, photo by David Handley

Leaf Scorch

Leaf Scorch, photo by David Handley

Black root rot is a disease complex which can be brought on by a combination of factors, including nematodes, soil fungi (Rhizoctonia, Pythium), herbicide carryover, and soil compaction. Plants become weak and may wilt and die. Roots on affected plants are black and poorly developed. This tends to be a problem in fields that have been in strawberries constantly for many seasons, and in fields that are under stress in other ways, such as winter injury. Rotating fields to crops other than strawberries for at least three years is an important management strategy for black root rot. Improving soil drainage and breaking up hardpans in the soil may also help. Pre-plant root dips with azoxystrobin (Abound®) may also reduce incidence of black root rot in some fields.

INSECTS
If black vine weevils or strawberry root weevils are a problem in a strawberry field that you would like to carry over, bifenthrin (Brigade®, Bifenture®) can be applied when adult feeding is noticed (usually until mid-late July). Look for notching along the leaf edges and the presence of the black or brown snout beetles. Applications should be made at night when these insects are active, and the highest rate of the insecticide should be used. For control of the grubs a soil drench of Platinum® (thiamethoxam) insecticide should be applied during the fall and/or early spring when the grubs are active in the soil. This product has a 50-day pre-harvest interval and may also be used as a pre-plant or planting treatment for root weevils. Parasitic nematodes such as Heterorhabditis bacteriophora or Steinernema feltiae can also be applied to provide control of root weevil grubs in late August. Nematodes require specialized handling and application. Contact us or talk with one of the suppliers for more details. See the New England Small Fruit Management Guide for sources.

Black Vine Weevil

Black Vine Weevil, photo by David Handley

Strawberry Root Weevil Grub

Strawberry Root Weevil Grub, photo by David Handley

White grubs have been a problem in some fields in recent years. The grubs may be the larvae of several species of scarab beetles, including June beetles, rose chafers, Japanese beetles, Asiatic garden beetles and European chafers. The beetles lay their eggs in June and July and the grubs feed on the roots of strawberries from July through mid-September. Affected plants will be stunted and wilted and may die during dry periods. Pulling up plants reveals that roots have been chewed off about an inch below the soil line. Sifting through the soil below the plants may reveal the whitish crescent-shaped grubs which can range in size from 3/8 inch to almost 1 ½ inches long, with six legs near the head and a swollen rear-end. The two most effective periods to treat plantings for grubs are in the spring prior to when they pupate (May) and in the late summer when the next generation is actively feeding (late August). Materials should be applied with plenty of water to moist soil to be sure they reach the root zone. Materials currently registered for control of grubs include Platinum® and Admire Pro®. Parasitic nematodes can also provide control of grubs and should be applied with similar timing. Nematodes are very sensitive to ultraviolet light and dehydration and must be applied with lots of water. See the New England Small Fruit Management Guide for sources of parasitic nematodes.

Strawberry rootworm (not root weevil) is a small (1/8″) dark brown to black beetle that feeds on strawberry foliage, causing it to look skeletonized. The small larvae feed on strawberry roots, further weakening the plant. Adult feeding damage on the leaves usually occurs in late July through August. Heavy rootworm feeding weakens strawberry plants so control is warranted when injury is noticed. Sevin® is registered for control of root worm after harvest.

Strawberry Rootworm Beetle

Strawberry Rootworm Beetle, photo by James Dill

Potato Leafhopper

Potato Leafhopper, photo by James Dill

Keep a lookout for potato leafhoppers; the injury has been very common in new strawberry beds this year. The potato leafhopper does not overwinter in Maine, but must fly in from southern states. These small, bullet-shaped insects feed on plant sap from the undersides of leaves, causing the leaves to become curled, stunted and yellow-streaked. Symptoms are often first noticed in new strawberry plantings, but leafhoppers will also infest older plantings and a variety of vegetables, flowers and fruit crops. To scout for leafhoppers, brush the leaves of the plants with your hand. The small, whitish adults can be seen flying off the plant. Examine the underside of some injured leaves. Look for small, light green leafhopper nymphs. They are about 1/16 inch long. When touched, they will crawl sideways in a crab-like manner. Controls for potato leafhoppers include Assail®, malathion, carbaryl or Provado®.

MITES
Two-spotted spider mites can increase significantly during the summer, especially in hot, dry weather. Continue to take leaf samples for spider mites throughout the summer. If more than 25% of a 60-leaf sample has mites, controls should be applied. Summer is an ideal time to use predatory mites to control pest mites, because they prefer warm temperatures, and there is less chance of an insecticide spray that might kill them. Amblyseius fallacis can provide good control of two-spotted spider mites when they are released at a rate of about 10,000 mites per acre. Predator mite releases should only be made after a spider mite infestation has been found in the field. Releasing predators into a clean field will often result in them dying, due to a lack of food. See the New England Small Fruit Management Guide for sources of predatory mites.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Cyclamen Mite Damage

Cyclamen Mite Damage, photo by David Handley

Cyclamen mites:  If your field had cyclamen mite symptoms this spring, summer is a good time to control them. After mowing off the leaves, access to the crowns where the mites reside is greatly improved. Plants showing weak growth and yellow, crinkled leaves may be infested with cyclamen mite. These mites are very small and reside down in the crown of the strawberry plant feeding on the developing leaves. They are very hard to see, even with magnification. The miticide Portal® can be effective, but must be applied with lots of water (200 gals.) to be sure that the material is carried down into the crowns.

WEEDS:  Weeds can become a big problem during the summer because they are often forgotten among all the other demands on our time and because of limited control options. However, the importance of good weed management should not be underestimated. Keeping weeds under control this summer will prevent future infestations. Here’s a summary of weed control options for established strawberry beds:

  1. Cultivation: Following renovation, cultivation between strawberry rows can provide effective temporary control of annual weeds. Several types of cultivators are available which will work well in strawberry beds. Cultivators can also be used to help sweep runners into the plant rows.
  1. DCPA (Dacthal®): A pre-emergent herbicide used in the early spring, late fall or after renovation. It offers good short-term control of some annual broadleaf weeds and grasses. It is weak on ragweed, galinsoga, smartweed, shepherd’s purse and mustard. Its action will be improved if worked into the soil by irrigation or light cultivation, and it tends to work best in lighter, warmer soils. This may be used as an alternative to terbacil or napropamide when there is a high risk of plant injury from those products.
  1. Napropamide (Devrinol®): This pre-emergent herbicide provides good control of annual grasses, volunteer grains and some broadleaf weeds. It is typically applied just before mulching in the fall. Split applications have become popular due to the loss of other pre-emergent herbicides, e.g. half maximum rate application after renovation or in late summer after desired daughter plants have rooted, and a second half rate application once the strawberry plants are dormant. Napropamide should be activated by irrigation, rainfall or light cultivation within 24 hours of application. Repeated long-term use of this material, i.e. with no crop rotation, may eventually result in poor daughter plant establishment, due to rooting inhibition.
  1. Terbacil (Sinbar®): An effective pre-emergent herbicide with some post-emergent activity, which should be applied at renovation time – after mowing and tilling the beds, but before new growth begins. A second application can be made in late fall, after the plants are dormant. No more than 6 oz. may be applied in a single application, and no more than 8 oz. may be applied in one season. An example of one season’s use could be 5 oz. applied at renovation and 3 oz. applied in the late fall, the latter in addition to napropamide or DCPA. Terbacil can cause injury to strawberry plants. It is important to determine appropriate rates for each location.
  1. Clopyralid (Spur®): Has both pre-emergent and post emergent activity on many weeds. One application per crop per year following harvest to emerged weeds. Apply uniformly in a minimum of 10 gallons of water per acre. Do not tank mix with other herbicides. Offers control of clover, dandelion and thistle.
  1. Sethoxydim (Poast®): A post-emergent herbicide for control of actively growing grasses. It will not control broadleaf weeds. It should not be applied when grasses are under stress, e.g. drought, or on unusually hot, humid days. Do not use sethoxydim within 6 weeks of terbacil (Sinbar®) applications, to avoid leaf injury. Sethoxydim should be used in combination with a crop oil concentrate. Do not tank mix with 2, 4-D. A second application is often needed for control of perennial grasses.
  1. Clethodim (Arrow®, Prism®, Select®): A post-emergent herbicide, similar in activity to Poastâ, for control of actively growing grasses. It will not control broadleaf weeds. It should not be applied when grasses are under stress, e.g. drought, or on unusually hot, humid days. Clethodim should be used in combination with a crop oil concentrate.
  1. Paraquat (Gramoxone Inteon®): A contact herbicide for post-emergent control of most annual weeds and suppression of many perennial weeds. Paraquat will injure or kill strawberries, so applications are made between rows only, with a sprayer shielded to protect the strawberries. It should be used in combination with a nonionic surfactant. Paraquat should not be applied within 21 days of harvest or more than three times in one season.
  1. Pelargonic Acid (Scythe®): A contact herbicide for post-emergent control of most annual weeds and suppression of many perennial weeds. Scythe® will injure or kill strawberries, so applications are made only between rows, with a sprayer shielded to protect the strawberries. This product no residual soil activity. It has a strong, unpleasant odor.
  1. 2,4-D Amine (Formula 40®, Amine 4): A post-emergent herbicide effective on most broadleaf perennial weeds. It will not control grasses, nor offer any pre-emergent control. 2,4-D should be applied immediately after harvest is complete if emerged broadleaf weeds are a problem. After application, the bed should be left undisturbed for three to five days, before mowing the leaves off the plants. This allows time for the material to be taken in by the weeds. This material can also be used when the plants are dormant (late fall or early spring) to control winter annuals and biennials. Fall applications may result in injury to the strawberries if the plants are not completely dormant. Do not tank mix 2,4-D with sethoxydim (Poast®).
  1. Flumloxazin (Chateau®): A pre-emergent herbicide for control of broadleaf weeds, including dandelion and shepherd’s purse. For use in the fall when plants are dormant for control of weeds the following spring.
  1. Pendimethalin (Prowl H20®): A pre-emergent herbicide that may be applied as a band with a shielded sprayer between the rows of strawberries. No weed control will be provided within the plant rows, and contact of this product on the strawberry plants will cause injury. May not be applied within 35 days of harvest.

The use of herbicides alone rarely gives complete weed control. Some hand weeding will be necessary. To provide good weed control throughout the life of a strawberry bed, growers should concentrate on crop rotation and good pre-plant weed control.

Strawberry Bed Renovation Review

Bed renovation should begin as soon after harvest as possible. The earlier the beds get renovated, the more time runner plants have to develop, which means larger crowns and more flower buds for next year. Early renovation also improves weed management by tilling in many weeds before they go to seed, and can help with insect, mite and foliar disease control by interfering with life cycles at a critical stage of development. The first step in the bed renovation process is to determine which beds should be carried over for another year and which should be plowed down and put into a crop rotation. Beds that did not suffer much from winter injury had good production and a good plant stand with no major weed, insect or disease problems should be carried over for another year. Beds that do not meet these criteria should be plowed down and seeded to a suitable cover crop to reduce weed, insect and disease problems that have developed, and to increase soil organic matter content. Ideally, beds that are plowed down should be rotated out of strawberries for at least three years. If properly managed, crop rotation will greatly reduce pest problems and improve the vigor and longevity of strawberry beds without the need for soil fumigation.

Renovating a strawberry bed is basically a thinning process to promote healthy new growth that can support a good crop next spring. While some parts of the following renovation scheme may be modified for individual situations, all beds should undergo the following steps once harvest is complete.

  1. Broadleaf weed control: If perennial broadleaf weeds such as dandelion, shepherd’s purse, daisy or goldenrod are a problem and/or a high population of annual broadleaf weeds such as lambsquarters, sorrel or pigweed are present, hand-pull as many as possible, especially within the plant rows, and/or apply 2,4-D amine (Formula 40®), or clopyralid (Spur®).
  1. Leaf mowing: Four to five days following the 2,4-D application (or immediately if 2,4-D was not applied) mow off the leaves of the strawberries about 1 ½ inches above the crowns. If the planting is weak, it is recommended that this step of the renovation process be skipped.
  2. Tilling Sides of Strawberry Rows

    Tilling Sides of Strawberry Rows, photo by David Handley

    Fertilization: Apply 40 to 60 pounds of actual nitrogen per acre (use the higher rate on sandy soils and fields where growth has been weak). Phosphorus and potassium applications should be made according to soil test recommendations. Soil testing kits and information are available from your county Cooperative Extension office.

  3. Plant thinning: For the single matted row system, strawberry plant rows should not be any wider than 24 inches. After mowing off the leaves, till the sides of the rows to narrow the beds back to a width of 12 to 18 inches. Use the wider setting for varieties that tend to throw few runners or any fields experiencing drought stress. Set the tiller so that it incorporates the mowed leaves and spreads about one inch of soil over the remaining crowns at the same time. This will reduce leaf disease and mite problems, and help stimulate new root growth on the remaining plants.
  1. Pre-emergent weed control: To control annual weeds, apply terbacil (Sinbar® 80WP) according to label directions (2 to 6 oz. per acre). Be sure to follow all label precautions. To avoid plant injury, do not use terbacil if you do not intend to mow off the leaves. Napropamide (Devrinol®) or DCPA (Dacthal®) may be used as an alternative to terbacil at this time, as described below. If you are not using herbicides, regular cultivation, before weeds are more than 2” tall, will be needed throughout the summer.
  2. Strawberry Irrigation

    Strawberry Irrigation, photo by David Handley

    Subsoiling: Soil compaction caused by tractor and picker traffic in the field can cause soil drainage problems and interfere with good root development. Using a subsoiling blade between the rows will break up compacted layers of soil and improve water infiltration. Subsoiling is best done late in the renovation sequence to prevent interference from straw and crop residues.

  1. Irrigation: To encourage rapid plant growth and get the most out of fertilizers and herbicides, irrigate the beds regularly. Strawberries will grow best if they receive 1 ½ inches of water per week during the growing season.

Don’t forget your plants once these renovation steps are completed. Check the strawberry fields regularly during the summer for pest problems. Finding and managing problems early can prevent major problems next spring. Pay close attention to the following items.

NUTRITION
Following the application of 40 to 60 pounds of actual nitrogen at renovation, another 20 pounds of nitrogen should be applied in mid- to late-August to stimulate flower bud development. One way to determine the nutrient status of strawberry plants during the summer is to have a leaf tissue analysis done. Tissue analysis offers a view of what is happening within the plant, and can spot any nutrient deficiencies. In combination with regular soil tests, tissue analysis will provide a complete picture of a field’s fertilizer needs. For more information about tissue analysis contact the Analytical Lab and Maine Soil Testing Service, 5722 Deering Hall, Room 407, University of Maine, Orono, ME 04469-5722, telephone: 207.581.2945.

Pest Management for Day-Neutral Strawberries

Most of the important pests that damage June-bearing varieties can be as much or more of a problem on day-neutral types. Because day-neutral strawberries will have buds, flowers and fruit all occurring at the same time, it is critical to pay close attention to the required number of days to harvest after a pesticide application, to be sure you can safely harvest ripe fruit while still protecting buds and blossoms. Some of the more important pests are listed below, along with currently recommended pesticides and days to harvest as stated on current labels.

Male and Female Spotted Wing Drosophila Flies

Male (left) and Female (right) Spotted Wing Drosophila, photo by Griffin Dill. Actual size: 2-3 mm.

Spotted wing drosophila (Drosophila suzukii) is a new pest, which is a concern for day-neutral strawberries, fall raspberries and blueberries. This is a small fruit fly, similar to those that hover around the bananas in your kitchen. However, this species will lay its eggs on fruit before it ripens, resulting in fruit that is contaminated with small white maggots just as it is ready to pick. Infested fruit quickly rots and has no shelf life. This insect can complete a generation in under two weeks, with each adult female laying hundreds of eggs. Therefore, millions of flies can be present soon after the introduction of just a few into a field. Frequently repeated insecticide sprays (1 to 2 per week) may be needed to prevent infestations once the insect is present in a field. Spotted winged drosophila can successfully overwinter here, although it may not build up to damaging levels until late in the summer. We have set out monitoring traps for spotted winged drosophila in fruit plantings around the state, and have found that they are already active this season. However, these traps may not provide adequate early warning, i.e. when we find them in a trap they are probably already established in the field. Products that provide good control of drosophila on strawberries include Radiant®, Brigade®, Danitol®, malathion and Assail®. Keeping fields clean of over-ripe and rotten fruit will also help reduce the incidence of this insect. For more information on identifying spotted wing drosophila and updates on populations around the state, visit our Spotted Wing Drosophila blog.

Tarnished plant bug:  This is one of the most prevalent and persistent pests of day-neutral strawberries, because summer flowering coincides with peak populations of this insect. Adult and nymph stages feed on the flowers and developing fruit, causing them to have seedy ends and other malformations. Regular insecticide applications are often required to keep the damage in check. Scout the flower clusters for adults and nymphs often to determine if controls are necessary. Insecticide products for tarnished plant bug include:

Tarnished Plant Bug

Tarnished Plant Bug, photo by Charles Armstrong

Tarnished Plant Bug
Product Days to Harvest
Brigade® 0
Pyganic® 0
Assail® 1
Dibrom® 1
Rimon® 1
malathion 3

Two-spotted spider mites:  Mites can become a problem during the summer when the growing conditions are warm and dry. In addition to infesting the leaves, mites can move onto the fruit, reducing marketability. Plants that are drought-stressed, over fertilized with nitrogen, or prone to dust covering, e.g. growing beside a dirt road, are especially prone to mite infestation. Predatory mites can be an effective means to control spider mites and keep them in check over the season. Releases should only be made when spider mites are present in the field to provide the predators with a source of food. Most of the products labeled for controlling spider mites will also kill predatory mites; so, do not use these products after predators have been released. Scout for mites often during the season by examining the undersides of the leaves. Control is warranted if more the 25% of leaves examined have mites.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Two-Spotted Spider Mites
Product Days to Harvest
Brigade® 0
Zeal® 1
Vendex® 1
Acramite® 1
Danitol® 2
Agri-Mek® 2
Oberon® 3
Savey® 3
Kelthane® 3

Potato leafhoppers, sap beetles, thrips and spittlebugs may also become problems on day-neutral strawberries, but are less frequently observed than tarnished plant bug and spider mites. Recommendations for these insects can be found in the current edition of the New England Small Fruit Management Guide.

Foliar and fruit diseases also need to be managed on day-neutral strawberries, and should be controlled in much the same way as they are for June-bearing varieties. Most of the fungicide products labeled to control gray mold, powdery mildew, leaf spot and leaf scorch have either zero or one day to harvest, so protecting blossoms at the same time as fruit is near harvest should not be a problem; but be sure to check labels carefully and schedule your sprays and harvests accordingly. Anthracnose fruit rot can be especially troublesome for day-neutral strawberries, because it grows well under warm conditions and spreads by splashing water, which is encouraged on plastic mulch. Fungicides registered for control of anthracnose include Cabrio®, Abound®, Pristine® and Switch®, all of which have zero days to harvest restriction.

Visit the 2017-2018 New England Small Fruit Management Guide online for more detailed pest information.

Hold the Dates:

Fruit and Vegetable Growers Field Day at Highmoor Farm: Wednesday July 26, 2017 from 8:30 a.m. to 3:00 p.m. Visit the Highmoor Farm website for more information. Please register by July 17! Call 933.2100 for additional registration information.

New England Vegetable & Fruit Conference is scheduled for December 12-14, 2017 in Manchester, NH.  Please visit the website, https://newenglandvfc.org/. Details and registration information coming soon.

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management
P.O. Box 179                             491 College Avenue
Monmouth, ME  04259         Orono, ME  04473
207.933.2100                           1.800.287.0279

Where brand names are used it is for the reader’s information. No endorsement is implied nor is any discrimination intended against products with similar ingredients. Always consult product label for rates, application instructions and safety precautions. Users of these products assume all associated risks.

The University of Maine is an equal opportunity/affirmative action institution.

Strawberry IPM Newsletter No. 5 – June 16, 2017

Friday, June 16th, 2017

StrawberriesStrawberry IPM Newsletter No. 5 – June 16, 2017
Click on photos to enlarge.

STRAWBERRY HARVEST SEASON NEAR IN SOUTHERN MAINE

Are Your Fields Ready for Customers?

Situation:
A few ripe berries can be found in southern Maine this week. Most growers are expecting the start of the harvest season to be about a week late. Pest pressure was again very low this week, and many fields are now beyond the bloom stage when clipper or tarnished plant bug can cause significant injury.  Mites and both foliar and fruit rot diseases still have the potential to become problems, so growers should continue monitoring for symptoms, and protecting late flowering varieties with fungicides if wet weather persists in the coming days. The Strawberry IPM Newsletter will take the next couple of weeks off and return with the annual renovation issue in July.

Strawberry bud weevil or “clipper” is no longer a threat for strawberry fields in southern and mid-state regions, as few flower buds remain for them to infest. No fresh injury or clippers were found in the fields scouted this week. However, you should continue to scout for clipped buds if you still have late varieties that are flowering.

Tarnished plant bug activity continues to be very low. We have seen occasional adult bugs in the fields, but no nymphs were found this week. However, with the warmer, drier weather forecast, and more fields coming into bloom, fields should be scouted regularly and often for both adults and nymphs. The control threshold for nymphs is 4 or more flower clusters infested per 30 sampled.

Two-spotted spider mites were found over the spray threshold (25% infested leaves) in just one southern field this week. While mites have been generally low this spring, it is important to keep scouting for them through the summer to prevent heavy populations from building up and weakening the plants as they set up fruit buds and prepare for the winter.

Sap beetle on strawberry

Picnic Beetle (left) on Strawberry, photo by James Dill

Sap beetles: Growers should keep an eye out for damage as the berries start to ripen. The 1/8 inch-long, dark brown beetles chew small holes in ripening fruit, similar to slug injury. They may be found in the holes they’ve chewed, but often drop to the ground when disturbed. The best management strategy for sap beetles is good sanitation. Keep the field free of overripe fruit by picking often and thoroughly. Insecticide sprays for this pest can be effective, but should be a last resort during the harvest period. Assail®, Brigade®, Dibrom® and PyGanic® are registered for control of sap beetles with pre-harvest intervals ranging from 12 to 24 hours. Read the product label carefully for this and other application instructions and restrictions.

Birds, especially cedar waxwings, are moving into fields to feed on ripe fruit. Only by keeping a near constant presence in the field and eliminating roosting sites can you reduce the damage. Some chemical repellents containing methyl anthranilate (e.g. Avian Control®), are registered for use on strawberries. Although most scientific studies with these products have not found them to be very effective, some growers have claimed good results. Remember that songbirds are protected by law and should not be killed. However, permits may be issued for killing birds by the U.S. Fish and Wildlife Service if they receive a recommendation for such a permit from the Maine Wildlife Services Office (part of the USDA Animal and Plant Health Inspection Service) in Augusta, along with an application from the grower. There is a $50 fee for the application, and it may take over a month for the permit to be processed.  However, the permit is good for one year, so if you have problems this season, you may consider applying for a permit this winter, which would allow you an option to kill birds, if necessary, next season. The Wildlife Damage Office has recommendations for managing birds in crops, and also has some control options available through their office. For more information on permits or bird control contact the office in Augusta at 207.629.5181. The office is located in the Capital West Business Center at 79 Leighton Road in Augusta.

Powdery Mildew

Powdery Mildew, photo by David Handley

Diseases:  Once the strawberries are beyond the bloom stage, fungicide applications for gray mold can usually be stopped for the season, unless there are a lot of rainy days as the fruit progress toward harvest. Keep an eye out for brown patches or spots developing on the fruit, especially around the calyxes, that could indicate an early gray mold infection.

Powdery mildew: We’re starting to see more fields with early indications of powdery mildew. Look for upward cupping of the leaves and reddish streaking or lesions on the leaf and flower stems. Consider using a fungicide that will control powdery mildew, such as captan + Topsin-M®, or Pristine® if you’re still spraying for gray mold. Those very close to harvest may want to wait until renovation after harvest to initiate a control program.

Annual Pre-Harvest Checklist for Pick-Your-Own
It’s that time again! As harvest approaches make sure that your farm is ready to provide your customers with the best possible picking experience. Take our annual review below to evaluate your customer readiness.

  • Your phone message and web/Facebook pages with picking conditions and opening and closing times are regularly updated.
  • Signs to the farm are neat and easy to read.
  • Girl with Quarts of Strawberries

    Strawberry Harvest, photo by David Handley

    There is easy access to the fields and plenty of parking.

  • Someone is ready to greet customers and offer parking instructions and directions to the field.
  • Access to the field is free of hazards.
  • Transportation is provided for the elderly and disabled.
  • The rules regarding picking are clearly posted.
  • Someone is in the field to show customers where to pick and to answer questions.
  • There are plenty of picking containers available.
  • Clean restroom and hand washing facilities are available.
  • Someone is available to help customers carry fruit out of the field.
  • The checkouts are fast and efficient.
  • Beverages are available.
  • Shade and seats are available for customers wanting to rest.
  • The help are friendly and knowledgeable.

A friendly, clean, and organized atmosphere will leave a lasting impression on your customers, encouraging them to come back and to recommend your farm to their friends.

REMINDER:
2017-2018 New England Small Fruit Management Guides
now available. Copies can be purchased through UMaine Extension at Highmoor Farm. Cost of the guide is $12.00 plus $2.63 postage for a total of $14.63. Please send checks made payable to UMaine Cooperative Extension and mail to: Highmoor Farm, P.O. Box 179, Monmouth, Maine 04259, attention Pam St. Peter. For more information, contact Pam St. Peter at 207.933.2100 or pamela.stpeter@maine.edu.

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                       Pest Management
P.O. Box 179                             491 College Avenue
Monmouth, ME  04259        Orono, ME  04473
207.933.2100                           1.800.287.0279

The University of Maine is an equal opportunity/ affirmative action institution.

Where brand names or company names are used it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

 

 

 

 

 

Strawberry IPM Newsletter No. 4 – June 9, 2017

Friday, June 9th, 2017

StrawberriesStrawberry IPM Newsletter No. 4 – June 9, 2017
Click on photos to enlarge.

STRAWBERRY INSECT PEST PRESSURE REMAINS LOW

Continue Protection Against Gray Mold through Bloom

Berry Growers Twilight Meeting
Tuesday, June 13, 2017 at 5:30 p.m.
Lavigne’s Farm in Sanford, Maine 04073
Venue phone: 207-324-5497

Situation:
Cool, wet weather continues to slow plant and flower development throughout the state. Many “early” fields are still in the full-late bloom stage, except in southern Maine where some green fruit is visible in early fields. Insect pest pressure has generally been low, but warmer, drier weather could bring about rapid changes in the situation. The high levels of moisture mean increased pressure from fungus diseases, so keep flowers and fruit protected with timely fungicide sprays any time significant precipitation is predicted during the bloom period.

Don’t forget! Twilight Meeting Tuesday June 13th, Lavigne’s Strawberry Farm, 158 Whichers Mill Road, Sanford, Maine 04073. Albert and Patrick Lavigne’s farm features large strawberry and high bush blueberry plantings. We’ll have a tour of the berry fields and have an opportunity to look over the equipment they use in their operation. The meeting will run from 5:30 p.m. to 7:30 p.m. Two pesticide applicator recertification credits will be available for attending the meeting.

Strawberry bud weevil or “clipper” remains low for this point in the season, with just two fields finding any clipper and only one of those over threshold. Most fields in southern Maine that are now passing full bloom are beyond the stage where clipper can cause significant damage, but if you still have late varieties with flowers still in bud, continue scouting for damage. Clipper damage is likely to increase on late varieties as temperatures get warmer in the coming days. Raspberry and blackberry growers should also scout for clipper damage; clippers will also attack the buds of these plants.

Tarnished plant bug activity continues to be very low. We have seen occasional adult bugs in the fields, but no nymphs were found this week. However, with the warmer, drier weather forecast, and more fields coming into bloom, fields should be scouted regularly and often for both adults and nymphs. The control threshold for nymphs is 4 or more flower clusters infested per 30 sampled.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Two-spotted spider mites were found over the spray threshold (25% infested leaves) in two southern fields this week, while another field was just under threshold. Expect populations to increase in the coming days as conditions become warmer and drier. It is important to scout for mites regularly, because they can increase rapidly when conditions are favorable.

Black vine weevil & strawberry root weevil:
As we approach the harvest season remember that this is the time when adult black vine weevils and strawberry root weevils to begin to emerge and start feeding on strawberry foliage. Look for notching along the leaf edges and the presence of the black or brown snout beetles. The weevils feed mostly at night and spend the daylight hours at the base of the plants under the mulch. They will be laying eggs during the harvest and post-harvest period. The larvae or grubs feed on the strawberry plant roots through the fall, overwinter deep in the soil and feed again in the spring, causing plants to weaken and die. Badly infested beds should be plowed up as soon after harvest as possible. Bifenthrin (Brigade®) can be applied to kill the adults when they emerge and start to feed on the leaves (usually until mid-late July). Applications should be made at night when the insects are active, and the highest rate of the insecticide should be used. Platinum® can be applied in the fall as a soil drench to control grubs before they go into the winter.

Black Vine Weevil

Black Vine Weevil, photo by David Handley

Strawberry Root Weevil Grub

Strawberry Root Weevil Grub, photo by David Handley

White grubs are the larvae of scarab beetles, including Japanese beetles, Asiatic garden beetles and European chafers.  Similar to the root weevils, the grubs feed on the roots of strawberry plants, but these tend to be larger, have noticeable legs and a swollen back end. White grubs are pupating now, and adults are beginning to emerge. These will soon be laying eggs at the base of the strawberry plants and a new generation of grubs will appear during the late summer and fall. Soil drenches with Admire Pro® or Platinum® can provide control of grubs in new plantings or following renovation in older plantings. Parasitic nematodes may also be applied in the spring and/or fall. See the New England Small Fruit Management Guide for details.

Slugs may be a problem in some fields this season. Moist conditions encourage the presence of these mollusks. Slugs usually feed at night, leaving large holes and tunnels in ripening fruit. Baits such as Deadline®  and Sluggo® offer some control of slugs, but should be used prior to fruit ripening. Pay close attention to label instructions and precautions. Baits should also be applied to the fields in mid-September if slugs have been a problem, to reduce egg-laying.

Slug on Strawberry

Slug on Strawberry, photo by James Dill

Gray Mold on Strawberries

Gray Mold on Strawberries, photo by James Dill

Diseases:  Most growers are continuing to use fungicides to protect flowers from gray mold spores. So many wet days during bloom has made keeping adequate coverage challenging. We typically find two to three fungicide applications during the bloom period adequate, but with a very extended bloom and lots of moisture, additional sprays have been needed in many fields to prevent infection.

Anthracnose fruit rot:  As fruit starts to size up and ripen in fields that are wet from recent rains, be on the lookout for this fruit rot. Anthracnose is favored by warm, humid conditions and can spread rapidly under rainy, wet conditions, especially if puddles remain in a field after the rain. Anthracnose appears as black sunken lesions with wet, orange (and sometimes gray) spore masses in them. The fungus is able to multiply on leaves without visible symptoms, which is why it may appear suddenly and widespread in a field.  Fungicides such as Cabrio® and Abound® can provide good control of anthracnose fruit rot.

Powdery mildew:  No severe symptoms of powdery mildew have been observed yet, but expect to see the problem become more noticeable with warmer, dry conditions. Look for upward cupping of the leaves and reddish streaking or lesions on the leaf and flower stems. Consider using a fungicide that will control powdery mildew, such as captan + Topsin-M®, or Pristine® if you’re still spraying for gray mold.

REMINDERS:

Protecting the endangered rusty patched bumble bee as well as other pollinators of berry crops will be the topic of a meeting sponsored by Cooperative Extension, the Wild Blueberry Commission of Maine, and US Fish and Wildlife Service on Wednesday, June 21, 2017 at 6:00 pm at the Waldoboro Cooperative Extension Office. For more information contact Dave Yarborough at 1-800-897-0757.

2017-2018 New England Small Fruit Management Guides now available. Copies can be purchased through UMaine Extension at Highmoor Farm. Cost of the guide is $12.00 plus $2.63 postage for a total of $14.63. Please send checks made payable to UMaine Cooperative Extension and mail to: Highmoor Farm, P.O. Box 179, Monmouth, Maine 04259, atten. Pam St. Peter. For more information, contact Pam St. Peter at 207.933.2100 or pamela.stpeter@maine.edu.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                      Pest Management
P.O. Box 179                             491 College Ave
Monmouth, ME  04259         Orono, ME  04473
207.933.2100                           1.800.287.0279

The University of Maine is an equal opportunity/ affirmative action institution.

Where brand names or company names are used, it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

 

Strawberry IPM Newsletter No. 3 – June 2, 2017

Monday, June 5th, 2017

Strawberry IPM Newsletter No. 3 – June 2, 2017
Click on photos to enlarge.

Strawberries

STRAWBERRY BLOOM TIME: MANAGE FUNGUS DISEASES

Scouting Report: Clipper Activity Increasing

Berry Growers Twilight Meeting
Tuesday, June 13, 2017 at 5:30 p.m.
Lavigne’s Farm in Sanford, Maine

Situation:
Many of the fields scouted this week are just in the early bloom to bloom stage, due to the continued cool, wet growing conditions. It looks as though it is going to be a late season, unless we soon see a significant change in the weather. The wet conditions should put growers on their guard for fungal diseases, including gray mold and leather rot, as these are typically more prevalent in a wet growing season.

Clipper Injury

Clipper Injury, Photo by David Handley

Strawberry bud weevil or “clipper” activity has increased over the past week.  Strawberry fields just coming into bloom in southern and coastal Maine were over the threshold of more than 1.2 clipped buds per 2 feet of row, and a spray was recommended. Clipper damage is likely to increase as temperatures warm and later varieties start coming into bloom. You should be scouting your fields for clipped buds now. Raspberry and blackberry growers beware; clippers will also attack the buds of these plants, although they do not appear to cause as much significant injury.

Tarnished plant bug activity continues to be very low.  We have seen a few more adult bugs in the fields, but no significant nymph populations. Fields coming into bloom should be scouted regularly and often for both adults and nymphs. The control threshold for nymphs is 4 or more flower clusters infested per 30 sampled.

Two-spotted spider mite numbers remain fairly low this week, although high overwintering populations have kept some fields at risk. Extended stretches of cool, wet weather can significantly reduce mite numbers, but populations can rebound quickly when warmer, drier weather returns. Two fields we scouted this week were over threshold. The extended outlook for continued cool, weather may help to keep mites in check for the near future, but it is important to scout for them regularly.

Strawberry rootworm (not root weevil) adults and feeding injury have been found on strawberry leaves in some fields this spring. The adult stage of this insect is a small (1/8”) dark brown beetle. The beetles feed on strawberry leaves during the spring and late summer, causing numerous small holes in the leaves. The adults in fields now will soon lay eggs. The larvae are small grubs that feed on the roots of strawberry plants, causing them to be stunted and weak. If these beetles and/or feeding injury is prevalent in a field, a treatment is recommended.  Sevin 50WP® is registered for control of this pest. Sprays can be timed to also control strawberry bud weevil. Strawberry rootworm should not be confused with root weevil, a larger insect that causes much more serious damage when present in a field.

Strawberry Rootworm Beetle

Strawberry Rootworm Beetle, photo by David Handley

Spittlebug

Spittlebug, photo by David Handley

Spittlebugs: The first spittlebugs of the season were found this week. The frothy spittle masses appear on the leaf stems (petioles), just below the leaflets. These typically start showing up around bloom. Although these spittlebugs don’t pose a significant threat to the plants, the frothy spittle they cover themselves with creates an annoyance for pickers. Adult spittlebugs are about ¼ inch long and bright green when they first emerge, but later turn dull yellow or brown. Spittlebugs overwinter as eggs and the nymphs emerge in late May. You should start to scout for spittlebugs when the plants are at about 10% bloom. Randomly inspect five one square foot areas per field every week. Spread the leaves and inspect the leaf bases, leaf stems, and flower stems looking for the white, frothy spittle masses. Spittlebugs tend to be a greater problem in weedy fields. Pesticides currently registered for spittlebug control include Provado®, Danitol® and Brigade®.

Diseases:  Most fields have had two to three fungicide applications to protect flowers from infection with Botrytis spores, the cause of gray mold. Infections are more likely to occur under moist conditions, so it is important to keep flowers protected during the rainy stretches we’re having. Two to three fungicide sprays 7-10 days apart are usually needed to provide good protection, but additional applications may be needed when there is continued rainfall and an extended bloom, such as we are experiencing this year.

Leather rot (Phytopthora cactorum) is certainly a concern for strawberry growers this year. This disease is more common when we have long stretches of cool, wet weather during bloom and fruit development, especially when in fields where standing water is common. Foliar sprays of Aliette®, Prophyt® or Phostrol® may be applied during bloom and fruit development to prevent leather rot.

Leaf Scorch

Leaf Scorch, photo by David Handley

Leaf spot & leaf scorch infections have been observed in most fields this week. Leaf spot usually appears on older leaves, as small purple or red spots with white centers. Under heavy infections, a number of spots may coalesce and give the leaf a burned appearance. Leaf scorch is another foliar disease with a similar diagnosis. The spots on the leaves tend to be smaller in the case of scorch, and lack the white centers. Many spots may coalesce to turn the leaves purple and necrotic, leading to the death of the leaf and weakening of the plant. Strawberry varieties vary greatly in their susceptibility to leaf spot and leaf scorch, with many having at least some resistance. However, under high disease pressure, many will show some symptoms. Fungicides registered for leaf spots include captan, Topsin-M®, Syllit®, Cabrio®, Nova® and Pristine®.

REMINDERS:

Twilight Meeting Tuesday June 13th, Lavigne’s Strawberry Farm, 158 Whichers Mill Road, Sanford, ME 04073. Albert and Patrick Lavigne’s farm features large strawberry and high bush blueberry plantings grown on very sandy soil. They have pursued extensive pond construction and irrigation development at the site and have adapted farm equipment to better suit their crops and growing practices. We’ll have a tour of the berry fields and pond construction, and discuss the challenges of water and nutrient management in these very light soils. We will also get an update on the berry pest situation around the state, and have an opportunity to look over the equipment they use and have adapted for their operation. The meeting will run from 5:30 p.m. to 7:30 p.m. We anticipate that two pesticide applicator recertification credits will be awarded for the meeting. Hold the date!

The rusty patched bumble bee was officially listed as an endangered species under the federal Endangered Species Act on March 21, 2017. Within Maine, the US Fish & Wildlife Service (USFWS) considers the rusty patched bumble bee to occur mainly in the Stockton Springs and Rockport area. Cooperative Extension, the Wild Blueberry Commission of Maine, and USFWS are holding a meeting on Wednesday, June 21, 2017 at 6:00 pm at the Waldoboro Extension Office to discuss the listing and potential restrictions to agricultural producers in the affected areas. We will also discuss measures to promote pollinator habitat and conserve native bees. For more information contact Dave Yarborough at 800-897-0757. We hope to see you June 21st.

2017-2018 New England Small Fruit Management Guides now available. Copies can be purchased through UMaine Extension at Highmoor Farm. The guide contains the latest information on management options for small fruit pests as well as cultural information. Cost of the guide is $12.00 plus $2.63 postage for a total of $14.63. Please send checks made payable to UMaine Cooperative Extension and mail to: Highmoor Farm, P.O. Box 179, Monmouth, Maine 04259, atten. Pam St. Peter. For more information, contact Pam St. Peter at 207.933.2100 or pamela.stpeter@maine.edu.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                      Pest Management
P.O. Box 179                             491 College Ave
Monmouth, ME  04259         Orono, ME  04473
207.933.2100                           1.800.287.0279

The University of Maine is an equal opportunity/ affirmative action institution.

Where brand names or company names are used, it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

 

 

 

 

 

 

Strawberry IPM Newsletter No. 2 – May 26, 2017

Friday, May 26th, 2017

StrawberriesStrawberry IPM Newsletter No. 2 – May 26, 2017
Click on photos to enlarge.

SLOW GROWTH IN THE STRAWBERRY FIELDS

Mites, Clipper Activity Increasing

Berry Growers Twilight Meeting
Tuesday, June 13, 2017 at 5:30 p.m.
Lavigne’s Farm in Sanford, Maine

Situation:
Cool, wet weather predominates, slowing strawberry development. Early fields in southern Maine are coming into bloom, with flower buds just starting to emerge in later varieties. Many growers have applied their first fungicide application for gray mold. Once spray materials have dried on the plants, they are generally considered “rainfast”, unless there is more than one inch of rainfall.  At that point, it should be assumed a significant portion of the spray has been washed off, and another application will be needed to assure adequate protection.

Twilight Meeting Tuesday June 13th, Lavigne’s Strawberry Farm, 158 Whichers Mill Road, Sanford, ME 04073. Albert and Patrick Lavigne’s farm features large strawberry and high bush blueberry plantings grown on very sandy soil. They have pursued extensive pond construction and irrigation development at the site and have adapted farm equipment to better suit their crops and growing practices. We’ll have a tour of the berry fields and pond construction, and discuss the challenges of water and nutrient management in these very light soils. We will also get an update on the berry pest situation around the state, and have an opportunity to look over the equipment they use and have adapted for their operation. The meeting will run from 5:30 p.m. to 7:30 p.m. We anticipate that two pesticide applicator recertification credits will be awarded for the meeting. Hold the date!

2017-2018 New England Small Fruit Management Guides are Here! Copies are available at Highmoor Farm. The guide contains the latest information on management options for small fruit pests as well as cultural information. Cost of the guide is $12.00 plus $2.63 postage for a total of $14.63.

To order the guides, please send your check made payable to UMaine Cooperative Extension mailed to: Highmoor Farm, P.O. Box 179, Monmouth, Maine 04259, attention Pam St. Peter. For more information, contact Pam St. Peter at 207.933.2100 or pamela.stpeter@maine.edu.

Members of the Maine Vegetable & Small Fruit Growers Association (MVSFGA) or the New England Vegetable & Berry Growers Association will receive free copies of the guide. For MVSFGA membership information, contact Bill Jordan at 207.799.1040.

Strawberry bud weevil or “clipper” activity has been low in most we’ve scouted this week. Only one field in Dresden was over the threshold of more than 1.2 clipped buds per two feet of row. We are seeing the small holes in the petals of opening flowers which indicate clipper feeding activity in many fields, but the females apparently are just starting to lay eggs and clip buds. We expect clipper damage to become more prevalent as temperatures warm and later varieties start coming into bloom. You should start scouting your fields for clipped buds now. Insecticide options for clipper include Lorsban®, Brigade®, Bifenture®, Danitol®, Sevin® and PyGanic®.

Clipper on Strawberry

Clipper on Strawberry, photo by David Handley

Tarnished Plant Bug Nymph on Strawberry Blossom

Tarnished Plant Bug Nymph on Strawberry Blossom, photo by David Handley

Tarnished plant bug activity has been low so far, this season.  We have seen adults in some fields, but so far have only found one nymph, so no sprays have been recommended. The nymphs can be hard to find, especially if the plants are wet. Young nymphs are very small (2 mm), active, yellow-green insects.  It is important to scout for them regularly, as they can appear very quickly. The threshold for nymphs is 4 or more flower clusters infested per 30 sampled. Start scouting any field with open flowers now. Insecticide options for tarnished plant bug include malathion, Assail®, Brigade®, Bifenture®, Dibrom®, Danitol®, and PyGanic®.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Two-spotted spider mites have been found in about half of the fields we scouted this week, and were over threshold in two fields. Although mites typically proliferate under hot, dry conditions, any plantings that harbored a high mite population last fall, which was hot and dry, are likely to see a problem with mites this spring. It is important to scout for mites regularly. If 25% of leaves sampled (e.g. 15 out of 60) have any mites, a spray should be applied. Chemical control options for two-spotted spider mites include Acramite®, Savey®, Zeal®, Portal®, Vendex®, Oberon®, Brigade®, Danitol®, and JMS Stylet oil® (oils will cause plant injury if used in combination with captan or within 14 days of an application of sulfur). Be sure to use enough liquid and pressure in the spray to get good coverage on the undersides of the leaves.

Cyclamen mites:  We found one field with light symptoms of cyclamen mite injury this week.  Infested plants show weak growth and shrunken, crinkled leaves. These mites are very small and reside in the crown of the strawberry plant, feeding on the developing leaves and flower buds. They are very hard to see, even with magnification. Portal® can be effective, but must be applied in lots of water to be sure that the material is carried down into the crowns where these mites reside.

Diseases:  As the fields come into bloom it is important to protect the flowers against infection by spores of the gray mold fungus, Botrytis cinerea. Most fruit infections take place through the flowers, so control efforts should be focused on the bloom period.  Two to three sprays of fungicide are typically required to provide good protection. The first spray is usually applied at 5-10% bloom, followed by a second application at petal fall. Additional applications may be applied if there is significant rainfall between or following these two sprays.

Leather rot (Phytopthora cactorum) may become a problem in fields where standing water is common during bloom and fruit development, especially if the fields were not mulched last fall. Incidence of leather rot can be reduced by applying straw mulch between the rows to prevent berries from touching the soil and reducing soil splashing onto the berries. Foliar sprays of Aliette®, Prophyt® or Phostrol® may be applied during bloom and fruit development to prevent leather rot when there has been excess moisture in a field, especially those with a history of this problem.

Powdery mildew:  We have seen early symptoms of this fungus disease in a few fields. It will become more prevalent when warmer weather arrives. It may first appear as purple or red blotches on the leaf and flower stems. Later, upward curling leaves and white, powdery growth on the undersides of the leaves becomes evident. Check your fields for pinkish purple leaf and flower stem lesions as new leaves emerge. Pristine®, Cabrio®, Topsin-M®, captan, Procure®, Torino® and JMS Stylet oil® are registered to control powdery mildew.

Leaf Spot on Strawberry Plant

Leaf Spot, photo by David Handley

Leaf spot is a fungal disease characterized by small purple spots with white centers on the leaves. The symptoms are often first visible on the older, lower leaves but often spread throughout the foliage. Spots or lesions may also appear on the leaf and flower stems. The fungus overwinters on older leaves and spreads with rain splashing in the spring. Severe infections can weaken plants, reducing fruit size, yield, and winter survival. We have seen lots of leaf spot in fields this spring. Varieties vary quite a bit in susceptibility to this disease. If you see leaf spot in your field, you should consider using a fungicide that will provide control as part of your spray program for gray mold. Products such as Captan®, Luna Sensation®, Mervion® and Pristine® have activity on both diseases.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                                  Pest Management
P.O. Box 179                                         491 College Ave
Monmouth, ME  04259                     Orono, ME  04473
207.933.2100                                       1.800.287.0279

Where brand names or company names are used, it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

The University of Maine is an equal opportunity/affirmative action institution.

 

 

 

 

Strawberry IPM Newsletter No. 1 – May 22, 2017

Monday, May 22nd, 2017

StrawberriesUniversity of Maine Strawberry IPM Newsletter

Strawberry IPM Newsletter No. 1 – May 22, 2017
Click on photos to enlarge.

2017 STRAWBERRY PEST MANAGEMENT SEASON BEGINS

Twilight Meeting Tuesday, June 13, Lavigne’s Farm, Sanford

Situation:
The extremely dry conditions of last year’s growing season will likely impact the 2017 berry crop. Many beds did not develop optimal plant populations because runner growth was poor, and runner rooting was delayed and weakened by the dry conditions. As a result, many beds look thinner than we would like and may have a somewhat smaller crop. On the brighter side, we are now out of the drought conditions, and there is good potential for thin plantings to recover with good runner production after harvest.

A winter that features wildly fluctuating temperatures is typically very hard on berry plants, but this past winter never saw extreme cold, and winter injury has only shown up in few plantings this spring. It has been most prevalent in older beds grown in heavier soils, and where straw mulch was not used for covering the plants. Winter injury can be diagnosed by cutting into the crowns of the strawberry plants. The internal tissue will show dark brown discoloration. To reduce the impact of winter injury, make sure the plants get plenty of water, and apply nutrients to encourage root growth and flower development, including nitrogen, calcium, and phosphorus. Heavy nitrogen fertilizer applications in the spring are not recommended, but up to 20 pounds of actual N (e.g. 125 lb. calcium nitrate) may improve early spring growth.

2017-2018 New England Small Fruit Management Guides are at the printers and will soon be available from UMaine Cooperative Extension. The guide contains the latest information on management options for small fruit pests as well as cultural information. We’ll make them available as soon as they arrive. While you’re waiting, the revised edition is already available on the UMass Extension website.

We will begin scouting strawberry fields for major insect pests next week, including volunteer farms in Wells, Limington, Cape Elizabeth, Minot, New Gloucester, Dresden, Monmouth, Wayne, and Farmington, and will be reporting our findings through this newsletter and blog on a weekly basis until harvest time. You can also get quick access to this information on the UMaine Pest Management web page at http://umaine.edu/ipm/.

The best way to manage strawberry pests is to scout your own fields regularly and often. You should start scouting regularly as soon as flower buds emerge from the crown. You should be able to identify the major pests and their damage, and be able to determine if control measures are necessary. To properly scout your fields, you may want a copy of the Strawberry Production Guide for the Northeast, Midwest and Eastern Canada. This contains detailed information on strawberry pest identification and monitoring, and also provides information on all other aspects of strawberry production. It may be purchased for $45.00 per copy from the University of Maine Cooperative Extension Publications Catalog online.

Strawberry bud weevil or “clipper” are becoming active as flower buds begin to emerge. Clipper activity has been observed in southern Maine this week. The clipper is a small weevil, which girdles strawberry flower buds, causing them to dry up and fall off the flower stalk. Scout for damage by counting the number of clipped buds in two feet of row length at five different locations in a field. If the average number of clipped buds per two-foot sample exceeds 1.2, or if live clippers are found, control measures are recommended. Damage is usually first noticed at the edges of the field. Border sprays may be effective in keeping this insect from becoming a problem in larger fields. Fields with a history of clipper problems will typically exceed threshold nearly every year. Insecticide options for clipper include Lorsban®, Brigade®, Sevin® and PyGanic®.

Clipper Beetle on Strawberry Bud

Clipper Beetle on Strawberry Bud, photo by James Dill

Large Tarnished Plant Bug Nymph

Third Instar Tarnished Plant Bug Nymph, photo by David Handley

Tarnished plant bugs adults will soon be laying eggs. Strawberries are one of their preferred hosts at this time of year. Once the eggs start to hatch, we’ll find the nymphs feeding in the flowers. The nymphs are small, active, yellow-green insects. It is important to scout for them regularly, as they can appear very quickly in warm weather. Tarnished plant bugs feed on the open strawberry flowers, causing the berries to have seedy ends. To scout for the nymphs, shake 30 flower clusters (six clusters in five different locations) over a plate. If four or more of the clusters out of the 30 sampled have any nymphs, control measures should be taken. Be on the alert and scout your fields as soon as open flowers appear! Insecticide options for tarnished plant bug include Assail®, Brigade®, Danitol®, Dibrom®, and PyGanic®.

Cyclamen mites:  Plants showing weak growth and yellow, pinkish or blackened, crinkled leaves may be infested with cyclamen mite. Cyclamen mites are very small, smaller than spider mites, and reside in the crown of the strawberry plant feeding on the developing leaves and flower buds. They are very hard to see, even with magnification. Infested plants have shrunken distorted leaves and flower stalks, and produce few, if any, marketable fruit. The miticide Portal® can be effective, but must be applied in lots of water and a spreader adjuvant to be sure that the material is carried down into the crowns where these mites reside.

Cyclamen Mite Damage on Strawberry Plant

Cyclamen Mite Damage on Strawberry Plant, photo by David Handley

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Two-spotted spider mites can be a problem in the spring, especially for plants under row covers. This is often where we first find mites. The cool wet weather of recent weeks has kept spider mite populations low (we haven’t seen any yet), but they will reproduce rapidly when warm weather arrives, so it is important to scout for them regularly. Spider mites mostly feed on the undersides of strawberry leaves, rasping the plant tissue and sucking the sap. Infested leaves will develop yellow flecking and a bronzed appearance. The plants become weakened and stunted. Fields that have had excessive nitrogen fertilizer and/or row covers tend to be most susceptible to mite injury. To scout for mites, collect 60 leaves from various locations in the field and examine the undersides for the presence of mites. Mites are very small – you may need a hand lens to see them. Chemical control options for two-spotted spider mites include Acramite®, Portal®, Nealta® Savey®, Zeal®, Vendex®, Oberon®, Brigade®, Danitol® and JMS Stylet Oil® (oils will cause plant injury if used in combination with captan or within 14 days of an application of sulfur).

Strawberry Root Weevil Grub

Strawberry Root Weevil Grub, photo by David Handley

Root weevil management
Fields that were infested with root weevils last summer should be inspected for grubs this spring. Infested plants appear week and stunted, usually in somewhat circular patches in a field. Digging under the plants will reveal small (1/4”-1/2”) crescent-shaped legless grubs. Typically, the grubs begin to pupate when the plants are in bloom. A soil drench of Platinum® (thiamethoxam) insecticide during the spring and/or fall when the grubs are active in the soil can provide control. However, Platinum® has a 50 day pre-harvest interval, so it is too late for applications in most fruiting fields this year.  Platinum® may also be used as a pre-plant or planting treatment for root weevils. It is not too late to put on an application of nematodes to control the grubs (optimal timing is about mid-May). Two species of nematodes appear to offer the best control of root weevil grubs. Heterorhabditis bacteriophora (Hb) appears to be the best candidate for control of root weevils when the soil temperature is above 60 degrees, and is available from Green Methods, www.greenmethods.com/site-info; the Integrated Biocontrol Network, www.biconet.com; and Koppert Biological Systems, www.koppertonline.com.

Nematodes are living organisms and they can be killed if they are misapplied. Order nematodes ahead of time and be ready to apply them through a sprayer or irrigation soon after they arrive. Refrigerate them if you cannot apply right away. Do not apply nematodes using a sprayer with a piston pump. Use clean equipment, removing all screens finer than 50-mesh. Apply nematodes in early morning or evening in a high volume of water to already moist soil, pre-irrigating if needed. Apply another ¼ inch of irrigation after application to wash them onto and into the soil. Researchers and suppliers recommended 250 (if banded in the row) to 500 million per acre, at a cost of $100-$200 per acre depending on volume and source. Nematodes tend to work best in heavily infested fields. Strawberry plants can recover their vigor remarkably well if crown feeding has not occurred and diseases haven’t taken over the roots.

Once the adults become active in July, bifenthrin (Brigade®) will provide some control if used at the highest labeled rates. The best timing for this spray is at night during the peak feeding activity of adults, before they start laying eggs, or about the time harvest ends.

White Grub

White Grub, Photo by David Handley

White grubs:  Weak growth noted in fields this spring may also be the result of white grubs feeding on the roots of newer plantings. These grubs are the larvae of beetles, including European chafer and Asiatic garden beetle. They differ from the larvae of black vine weevil and strawberry root weevil in that they have legs and a swollen anterior (rear end), and they tend to be larger. Their feeding weakens the plants by reducing the number of roots. The grubs can be found by pulling up weak plants and sifting through the soil that surrounded the roots. Controlling white grubs once they have become established in a field can be difficult. These tend to be more of a problem in new fields that have been planted following a grass rotation crop, because the adults prefer to lay their eggs in sod. Admire Pro®  and Platinum® insecticides are labeled for control of white grubs and should be applied within two hours of irrigation or rainfall to be sure the chemical gets into the root zone. Admire Pro® requires a 14 day to harvest interval, while Platinum® requires a 50 day pre-harvest interval.

Diseases:  Bloom is a critical time to protect strawberry fruit against gray mold caused by the fungus Botrytis cinerea, especially when conditions have been damp. Two to three sprays of fungicide during bloom are typically required to provide good protection against this disease. If you tank mix insecticides and fungicides, avoid spraying when bees are active. Botrytis cinerea overwinters on old leaves and plant debris. Fruit infections take place almost exclusively through the flowers, so gray mold control efforts must be focused on the bloom period. If the bloom period is dry and/or good fungicide coverage is maintained, incidence of gray mold at harvest should be low.

There are several excellent fungicide choices for control of gray mold in strawberries. Elevate® (fenhexamid) has good to excellent activity against Botrytis. Captevate® is a pre-mix of captan and fenhexamid and has a broader spectrum of activity than Elevate® alone. Switch® (cyprodinil and fludioxonil), Scala® (pyramethanil) and Pristine® (pyraclostrobin and boscalid) are also excellent products for gray mold control. Topsin M® + captan is also a good fungicide combination, but remember that captan is strictly a protectant and can be washed off by rain or irrigation water. Thiram is similarly effective but also susceptible to wash-off.

The fungicides Cabrio® (pyraclostrobin) and Abound® (azoxystrobin) are NOT suitable for gray mold control, but are effective against anthracnose and other fruit rot and leaf spot diseases. All fungicides mentioned above have a 0-day pre-harvest interval, except Topsin M® (1 day) and thiram (3 days). Remember to alternate fungicides with different modes of action for resistance management purposes.

Gray Mold on Strawberries

Gray Mold on Strawberries, photo by James Dill

Red Stele Symptoms on Strawberry Plant

Red Stele Symptoms on Strawberry Plant, photo by David Handley

Red stele root rot
Although early spring conditions were not especially conducive to red stele development, you should still be alert for this root rot if any fields appear to be weak, stunted or dying. To diagnose red stele, pull up a few plants that look weak and scrape the roots of these plants to see if the center of the root, known as the stele, is rusty red in color, instead of the normal white. The red color would indicate an infection. Red stele is caused by Phytophthora fragariae, a soil pathogen that infects roots when soils are wet with temperatures around 50°F. The pathogen grows into the roots causing the plants to become weak, stunted and to eventually die. Symptoms are most evident in the spring, and can be mistaken for winter injury. Ridomil Gold®, Alliette® or Phostrol® are fungicides that can be applied in the late fall or early spring for control of red stele. In newly planted beds, RootShield® may be applied as a pre-plant root dip to help prevent infections. Many varieties have some level of resistance to the disease, but the most effective management strategy is to plant only into well-drained soils, and/or plant onto raised beds.

Powdery mildew:  This fungus disease may first show up as purple or red blotches on the leaf petioles and flower stems in strawberry fields. Most of us are more familiar with the later symptoms of upward curling of the leaves and white, powdery growth on the undersides of the leaves. Some small infections of powdery mildew were observed in southern Maine this week. Check your fields for pinkish purple leaf and flower stem lesions as new leaves emerge. Pristine®, Cabrio®, Topsin-M®, captan, Procure®, Torino® and JMS Stylet Oil® are presently registered to control powdery mildew.

Powdery Mildew

Powdery Mildew, photo by David Handley

Angular Leaf Spot

Bacterial Angular Leaf Spot, Photo by David Handley

Angular leaf spot is a bacterial disease that is characterized by translucent leaf spots that may turn yellow and eventually black. The symptoms tend to start on the lower leaves but may move upwards as bacterial spores are splashed up by rain or irrigation water. Infection of the calyxes may result in a blackening of the berry stems and caps, reducing their marketability. Bacterial angular leaf spot is favored by extended cool, wet weather and nights with temperatures close to freezing. Frequent irrigation for frost protection can greatly encourage the development and spread of the disease, as will extended cool, damp weather. Susceptibility to this disease appears to vary significantly between varieties. The copper-containing material Kocide®, can reduce the spread of this disease. Start spray applications before bloom to prevent multiplication of the bacteria on the leaves before they jump to the berry caps. Application of copper sprays after bloom can result in fruit injury and is not recommended. Hydrogen dioxide (OxiDate®) may also have some activity against angular leaf spot when used on strawberries as part of a gray mold management program.

Other Berries:

Raspberries are showing little winter injury so far, but often winter injury becomes apparent once the floricanes start to flower. Tip dieback often occurs due to winter damage to the vascular tissue within the canes. Flower buds are starting to emerge on early varieties in southern Maine. These are susceptible to damage from strawberry bud weevil or clipper, as discussed above. Look for clipped buds and weevils regularly once the buds are visible.

Highbush blueberries are showing a very impressive bloom in most fields this spring, offering the potential of a very good crop, if conditions for development are right. If fruit set is heavy, be sure to supply adequate irrigation and nutrients during the growing season to support fruit development, reduce stress on the plants and to assure good bud development for next year. Mummy berry spores will soon be active. Expect infection periods to occur over the next few weeks, anytime there is a significant moisture event (rain, mist, fog). Protectant fungicides for mummy berry include Indar®, Orbit®, and Quilt Excel®.

Twilight Meeting Tuesday June 13th, Lavigne’s Strawberry Farm, 158 Whichers Mill Road, Sanford, ME 04073. Brothers Albert and Patrick Lavigne will be showcasing their farm, which features large strawberry and high bush blueberry plantings grown on very sandy soil. They have pursued extensive pond construction and irrigation development at the site and have adapted farm equipment to better suit their crops and growing practices. We’ll have a tour of the berry fields and pond construction, and discuss the challenges of water and nutrient management in these very light soils. We will also get an update on the berry pest situation around the state, and have an opportunity to look over the equipment they use and have adapted for their operation. The meeting will run from 5:30 p.m. to 7:30 p.m. More details to follow.  Hope to see you in Sanford!

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                      Pest Management
P.O. Box 179                             491 College Ave
Monmouth, ME  04259         Orono, ME  04473
207.933.2100                           1.800.287.0279

Where brand names or company names are used it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

Maine Cooperative Extension, the Land Grant University of the state of Maine and the U.S. Department of Agriculture Cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.  A Member of the University of Maine System.

 

 

 

 

Strawberry IPM Newsletter No. 6 – July 13, 2016

Thursday, July 14th, 2016

StrawberriesStrawberry IPM Newsletter No. 6 – July 13, 2016
Click on photos to enlarge.

RENOVATION AND WEED MANAGEMENT ISSUE

Time to Get Your Strawberry Beds Ready for Next Year

Time to Manage Pests in Day-Neutral Strawberries

It took a long time for winter to get started in 2015, leading to concerns about adequate cold acclimation for strawberry plants. In addition, not much snow fell in much of the state, increasing worries about winter injury. But, in the end, winter injury was very light to moderate in most fields. The crop was a little early and good overall, with strong customer demand. Heat and lack of rain shortened the season and reduced fruit size a bit. Pest pressure was relatively light in most fields. Spider mites and cyclamen mites were the most common problems across the state. Disease pressure was also light in most fields. Dry weather and timely fungicide sprays kept gray mold to a minimum, and foliar diseases, such as powdery mildew and leaf spot only began to show up towards the end of the season.

Now that harvest is coming to an end, don’t forget about your strawberry plants. Renovation of your beds should begin soon after harvest to allow as much time as possible for the plants to re-establish and form lots of healthy flower buds for next year. Follow the recommended renovation steps listed below for matted row strawberries. Continue to scout for and manage disease, insect and weed problems as they arise. Some of the more common issues to be alert for during the summer are listed below.

DISEASES
Foliar diseases should be monitored in your fields by regularly examining leaves. Foliar diseases are more likely to become apparent under wet weather conditions. The most common summer diseases are powdery mildew, leaf spot and leaf scorch. Fungicides available for these diseases include captan, Topsin-M®, Cabrio®, and Pristine®. See the New England Small Fruit Management Guide for detailed descriptions of these diseases and their management.

Powdery Mildew

Powdery Mildew, photo by David Handley

Leaf Spot

Leaf Spot, photo by David Handley

Black root rot is a disease complex which can be brought on by a combination of factors, including nematodes, soil fungi (Rhizoctonia, Pythium), herbicide carryover, and soil compaction. Plants become weak and may wilt and die. Roots on affected plants are black and poorly developed. This tends to be a problem in fields that have been in strawberries constantly for many seasons, and in fields that are under stress in other ways, such as winter injury. Rotating fields to crops other than strawberries for at least three years is an important management strategy for black root rot. Improving soil drainage and breaking up hardpans in the soil may also help. Pre-plant root dips with azoxystrobin (Abound®) may also reduce incidence of black root rot in some fields.

INSECTS
If black vine weevils or strawberry root weevils are a problem in a strawberry field that you would like to carry over, bifenthrin (Brigade®, Bifenture®) can be applied when adult feeding is noticed (usually until mid-late July). Look for notching along the leaf edges and the presence of the black or brown snout beetles. Applications should be made at night when these insects are active, and the highest rate of the insecticide should be used. For control of the grubs a soil drench of Platinum® (thiamethoxam) insecticide should be applied during the fall and/or early spring when the grubs are active in the soil. This product has a 50-day pre-harvest interval and may also be used as a pre-plant or planting treatment for root weevils. Parasitic nematodes such as Heterorhabditis bacteriophora or Steinernema feltiae can also be applied to provide control of root weevil grubs in late August. Nematodes require specialized handling and application. Contact us or talk with one of the suppliers for more details. See the New England Small Fruit Management Guide for sources.

Black Vine Weevil

Black Vine Weevil, photo by David Handley

Strawberry Root Weevil Grub

Strawberry Root Weevil Grub, photo by David Handley

White grubs have been a problem in some fields in recent years. The grubs may be the larvae of several species of scarab beetles, including June beetles, rose chafers, Japanese beetles, Asiatic garden beetles and European chafers. The beetles lay their eggs in June and July and the grubs feed on the roots of strawberries from July through mid-September. Affected plants will be stunted and wilted and may die during dry periods. Pulling up plants reveals that roots have been chewed off about an inch below the soil line. Sifting through the soil below the plants may reveal the whitish crescent-shaped grubs which can range in size from 3/8 inch to almost 1 ½ inches long, with six legs near the head and a swollen rear-end. The two most effective periods to treat plantings for grubs are in the spring prior to when they pupate (May) and in the late summer when the next generation is actively feeding (late August). Materials should be applied with plenty of water to moist soil to be sure they reach the root zone. Materials currently registered for control of grubs include Platinum® and Admire Pro®. Parasitic nematodes can also provide control of grubs and should be applied with similar timing. Nematodes are very sensitive to ultraviolet light and dehydration and must be applied with lots of water. See the New England Small Fruit Management Guide for sources of parasitic nematodes.

Strawberry rootworm (not root weevil) is a small (1/8″) dark brown to black beetle that feeds on strawberry foliage, causing it to look skeletonized. The small larvae feed on strawberry roots, further weakening the plant. Adult feeding damage on the leaves usually occurs in late July through August. Heavy rootworm feeding weakens strawberry plants so control is warranted when injury is noticed.

Strawberry Rootworm Beetle

Strawberry Rootworm Beetle, photo by James Dill

Potato Leafhopper

Potato Leafhopper, photo by James Dill

Keep a lookout for potato leafhoppers, which can weaken strawberry plants and spread disease. The potato leafhopper does not overwinter in Maine, but must fly in from southern states. These small, bullet-shaped insects feed on plant sap from the undersides of leaves, causing the leaves to become curled, stunted and yellow-streaked. Symptoms are often first noticed in new strawberry plantings, but leafhoppers will also infest older plantings and a variety of vegetables, flowers and fruit crops. To scout for leafhoppers, brush the leaves of the plants with your hand. The small, whitish adults can be seen flying off the plant. Examine the underside of some injured leaves. Look for small, light green leafhopper nymphs. They are about 1/16 inch long. When touched, they will crawl sideways in a crab-like manner. Controls for potato leafhoppers include malathion, carbaryl or Provado®.

MITES
Two-spotted spider mites can increase significantly during the summer, especially in hot, dry weather. Continue to take leaf samples for spider mites throughout the summer. If more than 25% of a 60-leaf sample has mites, controls should be applied. Summer is an ideal time to use predatory mites to control pest mites, because they prefer warm temperatures, and there is less chance of an insecticide spray that might kill them. Amblyseius fallacis can provide good control of two-spotted spider mites when they are released at a rate of about 10,000 mites per acre. Predator mite releases should only be made after a spider mite infestation has been found in the field. Releasing predators into a clean field will often result in them dying, due to a lack of food. See the New England Small Fruit Management Guide for sources of predatory mites.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Cyclamen Mite Damage

Cyclamen Mite Damage, photo by David Handley

Cyclamen mites: If your field had cyclamen mite symptoms this spring, summer is a good time to control them. Plants showing weak growth and yellow, crinkled leaves may be infested with cyclamen mite. These mites are very small and reside down in the crown of the strawberry plant feeding on the developing leaves. They are very hard to see, even with magnification. Miticides such as Thionex®, Kelthane® or Portal® can be effective, but must be applied with lots of water to be sure that the material is carried down into the crowns.

WEEDS
Weeds can become a big problem during the summer because they are often forgotten among all the other demands on our time and because of limited control options. However, the importance of good weed management should not be underestimated. Keeping weeds under control this summer will prevent future infestations. Here’s a summary of weed control options for strawberries:

  1. Cultivation: Following renovation, cultivation between strawberry rows can provide effective temporary control of annual weeds. Several types of cultivators are available which will work well in strawberry beds. Cultivators can also be used to help sweep runners into the plant rows.
  2. DCPA (Dacthal®): A pre-emergent herbicide used in the early spring, late fall or after renovation. It offers good, short-term control of some annual broadleaf weeds and grasses. It is weak on ragweed, galinsoga, smartweed, shepherd’s purse and mustard. Its action will be improved if worked into the soil by irrigation or light cultivation, and it tends to work best in lighter, warmer soils. This may be used as an alternative to terbacil or napropamide when there is a high risk of plant injury from those products.
  3. Napropamide (Devrinol®): A pre-emergent herbicide which provides good control of annual grasses, volunteer grains and some broadleaf weeds. It is typically applied just before mulching in the fall. Split applications have become popular due to the loss of other pre-emergent herbicides, e.g. half maximum rate application after renovation or in late summer after desired daughter plants have rooted, and a second half rate application once the strawberry plants are dormant. Napropamide should be activated by irrigation, rainfall or light cultivation within 24 hours of application. Repeated long-term use of this material, i.e. with no crop rotation, may eventually result in poor daughter plant establishment, due to rooting inhibition.
  4. Terbacil (Sinbar®): An effective pre-emergent herbicide with some post-emergent activity, which should be applied at renovation time – after mowing and tilling the beds, but before new growth begins. A second application can be made in late fall, after the plants are dormant. No more than 6 oz. may be applied in a single application, and no more than 8 oz. may be applied in one season. An example of one season’s use could be 5 oz. applied at renovation and 3 oz. applied in the late fall, the latter in addition to napropamide or DCPA. Terbacil can cause injury to strawberry plants. It is important to determine appropriate rates for each location.
  5. Clopyralid (Spur®): One application per crop per year following harvest to emerged weeds. Apply uniformly in a minimum of 10 gallons of water per acre. Do not tank mix with other herbicides. Offers control of clover, dandelion and thistle.
  6. Sethoxydim (Poast®): A post-emergent herbicide for control of actively growing grasses. It will not control broadleaf weeds. It should not be applied when grasses are under stress, e.g. drought, or on unusually hot, humid days. Do not use sethoxydim within 6 weeks of terbacil (Sinbar®) applications, to avoid leaf injury. Sethoxydim should be used in combination with a crop oil concentrate. Do not tank mix with 2, 4-D.
  7. Clethodim (Arrow®, Prism®, Select®): A post-emergent herbicide, similar in activity to Poast®, for control of actively growing grasses. It will not control broadleaf weeds. It should not be applied when grasses are under stress, e.g. drought, or on unusually hot, humid days. Clethodim should be used in combination with a crop oil concentrate.
  8. Paraquat (Gramoxone Inteon®): A contact herbicide for post-emergent control of most annual weeds and suppression of many perennial weeds. Paraquat will injure or kill strawberries, so applications are made between rows only, with a sprayer shielded to protect the strawberries. It should be used in combination with a nonionic surfactant. Paraquat should not be applied within 21 days of harvest or more than three times in one season.
  9. Pelargonic Acid (Scythe®): A contact herbicide for post-emergent control of most annual weeds and suppression of many perennial weeds. Scythe® will injure or kill strawberries, so applications are made between rows only, with a sprayer shielded to protect the strawberries. This product has a relatively low toxicity and no residual soil activity. It has a strong, unpleasant odor.
  10. 2,4-D Amine (Formula 40®, Amine 4): A post-emergent herbicide effective on most broadleaf perennial weeds. It will not control grasses, nor offer any pre-emergent control. 2,4-D should be applied immediately after harvest is complete if emerged broadleaf weeds are a problem. After application, the bed should be left undisturbed for three to five days, before mowing the leaves off the plants. This allows time for the material to be taken in by the weeds. This material can also be used when the plants are dormant (late fall or early spring) to control winter annuals and biennials. Fall applications may result in injury to the strawberries if the plants are not completely dormant. Do not tank mix 2,4-D with sethoxydim (Poast®).
  11. Flumloxazin (Chateau®): A pre-emergent herbicide for control of broadleaf weeds, including dandelion and shepherd’s purse. For use in the fall when plants are dormant for control of weeds the following spring.
  12. Pendimethalin (Prowl H20®): A pre-emergent herbicide that may be applied as a band with a shielded sprayer between the rows of strawberries. No weed control will be provided within the plant rows, and contact of this product on the strawberry plants will cause injury. May not be applied within 35 days of harvest.

The use of herbicides alone rarely gives complete weed control. Some hand weeding will be necessary. To provide good weed control throughout the life of a strawberry bed, growers should concentrate on crop rotation and good pre-plant weed control.

Strawberry Bed Renovation Review

Bed renovation should begin as soon after harvest as possible. The earlier the beds get renovated, the more time runner plants have to develop, which means larger crowns and more flower buds for next year. Early renovation also improves weed management by tilling in many weeds before they go to seed, and can help with insect and foliar disease control by interfering with life cycles at a critical stage of development. The first step in the bed renovation process is to determine which beds should be carried over for another year and which should be plowed down and put into a crop rotation. Beds that did not suffer much from winter injury had good production and a good plant stand with no major weed, insect or disease problems should be carried over for another year. Beds that do not meet these criteria should be plowed down and seeded to a suitable cover crop to reduce weed, insect and disease problems that have developed, and to increase soil organic matter content. Ideally, beds that are plowed down should be rotated out of strawberries for at least three years. If properly managed, crop rotation will greatly reduce pest problems and improve the vigor and longevity of strawberry beds without the need for soil fumigation.

Renovating a strawberry bed is basically a thinning process to promote healthy new growth that can support a good crop next spring. While some parts of the following renovation scheme may be modified for individual situations, all beds should undergo the following steps once harvest is complete.

  1. Broadleaf weed control: If perennial broadleaf weeds such as dandelion, shepherd’s purse, daisy or goldenrod are a problem and/or a high population of annual broadleaf weeds such as lambsquarters, sorrel or pigweed are present, hand-pull as many as possible, especially within the plant rows, and/or apply 2,4-D amine (Formula 40®), or clopyralid (Spur®).
  2. Mowing Strawberry Leaves

    Mowing Strawberry Leaves, photo by David Handley

    Leaf mowing: Four to five days following the 2,4-D application (or immediately if 2,4-D was not applied) mow off the leaves of the strawberries about 1 ½ inches above the crowns. If the planting is weak, it is recommended that this step of the renovation process be skipped.

  3. Fertilization: Apply 40 to 60 pounds of actual nitrogen per acre (use the higher rate on sandy soils and fields where growth has been weak). Phosphorus and potassium applications should be made according to soil test recommendations. Soil testing kits and information are available from your county Cooperative Extension office.
  4. Plant thinning: For the single matted row system, strawberry plant rows should not be any wider than 24 inches. After mowing off the leaves, till the sides of the rows to narrow the beds back to a width of 12 to 18 inches. Use the wider setting for varieties that tend to throw few runners or any fields experiencing drought stress. Set the tiller so that it incorporates the mowed leaves and spreads about one inch of soil over the remaining crowns at the same time. This will reduce leaf disease and mite problems, and help stimulate new root growth on the remaining plants.
  5. Pre-emergent weed control: To control annual weeds, apply terbacil (Sinbar® 80WP) according to label directions (2 to 6 oz. per acre). Be sure to follow all label precautions. To avoid plant injury, do not use terbacil if you do not intend to mow off the leaves. Napropamide (Devrinol®) or DCPA (Dacthal®) may be used as an alternative to terbacil at this time, as described below. If you are not using herbicides, regular cultivation, before weeds are more than 2” tall, will be needed throughout the summer.
  6. Strawberry Irrigation

    Strawberry Irrigation, photo by David Handley

    Subsoiling: Soil compaction caused by tractor and picker traffic in the field can cause soil drainage problems and interfere with good root development. Using a subsoiling blade between the rows will break up compacted layers of soil and improve water infiltration. Subsoiling is best done late in the renovation sequence to prevent interference from straw and crop residues.

  7. Irrigation: To encourage rapid plant growth and get the most out of fertilizers and herbicides, irrigate the beds regularly. Strawberries will grow best if they receive 1 ½ inches of water per week during the growing season.

Don’t forget your plants once these renovation steps are completed. Check the strawberry fields regularly during the summer for pest problems. Finding and managing problems early can prevent major problems next spring. Pay close attention to the following items.

NUTRITION
Following the application of 40 to 60 pounds of actual nitrogen at renovation, another 20 pounds of nitrogen should be applied in mid- to late-August to stimulate flower bud development. One way to determine the nutrient status of strawberry plants during the summer is to have a leaf tissue analysis done. Tissue analysis offers a view of what is happening within the plant, and can spot any nutrient deficiencies. In combination with regular soil tests, tissue analysis will provide a complete picture of a field’s fertilizer needs. For more information about tissue analysis contact: Analytical Lab and Maine Soil Testing Service, 5722 Deering Hall, Rm. 407, University of Maine, Orono, ME 04469-5722, telephone: 207.581.2945.

Pest Management for Day-Neutral Strawberries

Most of the important pests that damage June-bearing varieties can be as much or more of a problem on day-neutral types. Because day-neutral strawberries will have buds, flowers and fruit all occurring at the same time, it is critical to pay close attention to the required number of days to harvest after a pesticide application, to be sure you can safely harvest ripe fruit while still protecting buds and blossoms. Some of the more important pests are listed below, along with currently recommended pesticides and days to harvest as stated on current labels.

Spotted Wing Drosophila

Spotted Wing Drosophila, photo by James Dill

Spotted wing drosophila (Drosophila suzukii) is a new pest, which is a concern for day-neutral strawberries, fall raspberries and blueberries. This is a small fruit fly, similar to those that hover around the bananas in your kitchen. However, this species will lay its eggs on fruit before it ripens, resulting in fruit that is contaminated with small white maggots just as it is ready to pick. Infested fruit quickly rots and has no shelf life. This insect can complete a generation in under two weeks, with each adult female laying hundreds of eggs. Therefore, millions of flies can be present soon after the introduction of just a few into a field. Frequently repeated insecticide sprays (1 to 2 per week) may be needed to prevent infestations once the insect is present in a field. Spotted winged drosophila can successfully overwinter here, although it may not build up to damaging levels until late in the summer. We have set out monitoring traps for spotted winged drosophila in fruit plantings around the state to determine the activity of this pest in Maine. However, these traps may not provide adequate early warning, i.e. when we find them in a trap they are probably already established in the field. Products that provide good control of drosophila on strawberries include Radiant®, Brigade®, Danitol®, malathion and Assail®. Keeping fields clean of over-ripe and rotten fruit will also help reduce the incidence of this insect. For more information on identifying spotted wing drosophila and updates on populations around the state, visit our SWD blog at: http://umaine.edu/highmoor/blog/tag/spotted-wing-drosophila/. Other spotted wing drosophila resources include websites from Michigan State University, Pennsylvania State University, and University of New Hampshire.

Tarnished plant bug: This is one of the most prevalent and persistent pests of day-neutral strawberries, because summer flowering coincides with peak populations of this insect. Adult and nymph stages feed on the flowers and developing fruit, causing them to have seedy ends and other malformations. Regular insecticide applications are often required to keep the damage in check. Scout the flower clusters for adults and nymphs often to determine if controls are necessary. Insecticide products for tarnished plant bug include:

Tarnished Plant Bug

Tarnished Plant Bug, photo by Charles Armstrong

Tarnished Plant Bug
Product Days to Harvest
Brigade® 0
Pyganic® 0
Assail® 1
Dibrom® 1
Rimon® 1
malathion 3

Two-spotted spider mites: Mites can become a problem during the summer when the growing conditions are warm and dry. In addition to infesting the leaves, mites can move onto the fruit, reducing marketability. Plants that are drought-stressed, over fertilized with nitrogen, or prone to dust covering, e.g. growing beside a dirt road, are especially prone to mite infestation. Predatory mites can be an effective means to control spider mites and keep them in check over the season. Releases should only be made when spider mites are present in the field to provide the predators with a source of food. Most of the products labeled for controlling spider mites will also kill predatory mites; so do not use these products after predators have been released. Scout for mites often during the season by examining the undersides of the leaves. Control is warranted if more the 25% of leaves examined have mites.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Two-Spotted Spider Mites
Product Days to Harvest
Brigade® 0
Zeal® 1
Vendex® 1
Acramite® 1
Danitol® 2
Agri-Mek® 2
Oberon® 3
Savey® 3
Kelthane® 3

Potato leafhoppers, sap beetles, thrips and spittlebugs may also become problems on day-neutral strawberries, but are less frequently observed than tarnished plant bug and spider mites. Recommendations for these insects can be found in the current edition of the New England Small Fruit Management Guide.

Gray Mold on Strawberries

Gray Mold on Strawberries, photo by James Dill

Foliar and fruit diseases also need to be managed on day-neutral strawberries, and should be controlled in much the same way as they are for June-bearing varieties. Most of the fungicide products labeled to control gray mold, powdery mildew, leaf spot and leaf scorch have either zero or one day to harvest, so protecting blossoms at the same time as fruit is near harvest should not be a problem; but be sure to check labels carefully and schedule your sprays and harvests accordingly. Anthracnose fruit rot can be especially troublesome for day-neutral strawberries, because it grows well under warm conditions and spreads by splashing water, which is encouraged on plastic mulch. Fungicides registered for control of anthracnose include Cabrio®, Abound®, Pristine® and Switch®, all of which have zero days to harvest restriction.

Visit the 2015-2016 New England Small Fruit Management Guide online for more detailed pest information.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                       Pest Management
P.O. Box 179                             491 College Avenue
Monmouth, ME 04259          Orono, ME 04473
207.933.2100                           1.800.287.0279

Where brand names are used it is for the reader’s information. No endorsement is implied nor is any discrimination intended against products with similar ingredients. Always consult product label for rates, application instructions and safety precautions. Users of these products assume all associated risks.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the state of Maine and the U.S. Department of Agriculture Cooperating. Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

 


 

Strawberry IPM Newsletter No. 4 – June 10, 2016

Monday, June 20th, 2016

StrawberriesStrawberry IPM Newsletter No. 4 – June 10, 2016
Click on photos to enlarge.

SPIDER MITE AND TARNISHED PLANT BUG NUMBERS CLIMB

Southern Fields Nearing Harvest

Situation:
Some much-needed rain this week should help size-up berries that are nearing harvest in southern Maine. Hail however, was an unwanted addition to some storms and has caused some significant localized crop damage. Northern fields still have late varieties in bloom, and may still need protection against tarnished plant bug and gray mold infection. A few fruit are being harvested for stands from plasticulture plantings and fields put under row covers this spring.

Strawberry bud weevil or “clipper”
Most fields in Southern Maine are now beyond early bloom stage, when clipper can have an economic impact. If your fields still have late varieties in early bloom, you should continue scouting for clipper and apply controls if significant damage is noted to the buds. Be aware the clippers will move on to raspberries and blackberries and clip off their buds once the strawberries have come into bloom.

Large Tarnished Plant Bug Nymph

Third Instar Tarnished Plant Bug Nymph, photo by David Handley

Tarnished plant bug activity has been increasing in southern Maine this week, with two sites over the recommended spray threshold. More northern sites are still seeing very little, if any, activity. Continue to scout for the small, green nymphs until the primary (king) berries begin to color. Remember, these can build up fast. The threshold for nymphs is 4 or more flower clusters infested per 30 clusters sampled. Insecticide options for tarnished plant bug include malathion, Assail®, Brigade®, Bifenture®, Danitol®, and PyGanic®.  Thionex® is also labeled on strawberries for tarnished plant bug and spider mites, but this registration will soon expire.  All supplies must be used up by July 31, 2016.

Two-spotted spider mites continue to be the most widespread concern this week, with mites being found in nearly every field, and over the recommended spray threshold at three locations. Mites can build up very rapidly under warm, dry conditions. If 25% of leaves sampled  (e.g. 15 out of 60) have any mites, a spray should be applied.

Gray Mold on Strawberries

Gray Mold on Strawberries, photo by James Dill

Diseases: Many fields are getting ready for a second or third application of fungicide to prevent gray mold, in anticipation of weekend rains, which could result in more fungal spores being released to infect remaining flowers. Two to three sprays of fungicide through the bloom period are typically required to provide good protection.

Anthracnose fruit rot could be a threat when fields are wet during fruit development, especially under warmer temperatures, such as is often seen with plants grown on black plastic mulch. It may be best to use a fungicide product that offers control of both gray mold and anthracnose, such as Pristine® or Cabrio®.

Leather rot (Phytopthora cactorum) could also appear in fields if standing water is prevalent for an extended time following heavy rains or overhead irrigation. Aliette®, Agri-Phos® or Phostrol® applied during fruit development can help prevent leather rot when the risk of this disease is high. Fungicides typically used for gray mold are generally not effective on anthracnose.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                       Pest Management
P.O. Box 179                             491 College Avenue
Monmouth, ME  04259         Orono, ME  04473
207.933.2100                           1.800.287.0279

Maine Cooperative Extension, the Land Grant University of the state of Maine and the U.S. Department of Agriculture Cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.  A Member of the University of Maine System.

Where brand names or company names are used it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

 

 

 

 

Strawberry IPM Newsletter No. 3 – June 3, 2106

Monday, June 20th, 2016

StrawberriesStrawberry IPM Newsletter No. 3 – June 3, 2016
Click on photos to enlarge.

STRAWBERRY INSECT AND DISEASE PRESSURE LOW

Spider Mites Over Threshold in Several Fields

Vegetable and Berry Growers Twilight Meeting
Thursday, June 9, 2016 at 4:00 p.m.
McDougal’s Orchard in Springvale, Maine

Situation:
Continued dry weather has kept fungus disease pressure very low. Insect populations have also been low this week, but mite pressure has been increasing. Early varieties are now showing green fruit in southern Maine, while late varieties are now coming into bloom.

REMINDER: Twilight meeting, Thursday night
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a twilight meeting at McDougal’s Orchard in Springvale on Thursday, June 9 at 4:00 p.m. This will be a joint meeting with the Maine State Pomological Society.  Trevor Hardy of Brookdale Farm and George Hamilton from the University of New Hampshire will be on hand to discuss the latest developments in irrigation equipment for fruit and vegetable growers. We will tour some of the orchard and berry plantings at the farm, courtesy of Ellen and Jack McAdam, and see some of the new deer fence. In addition, we’ll discuss the upcoming season and pest management issues facing vegetable and berry growers this year.  McDougal Orchard is located at 201 Hanson Ridge Road in Springvale, Maine.  You can visit their website at: http://www.mcdougalorchards.com/index.php.

Clipper Beetle on Strawberry Bud

Strawberry bud weevil or “clipper” Most fields in Southern Maine are now beyond early bloom stage, when clipper can have an economic impact. However there may be some late blooming varieties in more northern sites that could still see significant damage from clipper; so scout any fields/varieties that have not yet reached full bloom, looking for clipped buds and/or live adults. If there are more than an average of 1.2 clipped buds per two feet of row, or live clippers are present, a spray should be applied. Insecticide options for clipper include Brigade®, Bifenture®, Danitol®, Sevin® and PyGanic®.

Tarnished plant bug activity has been very low this week, with no fields over the recommended spray threshold. The nymphs can still cause damage beyond the bloom stage, so continue to scout for them until the primary (king) berries begin to color. The threshold for nymphs is 4 or more flower clusters infested per 30 clusters sampled. Insecticide options for tarnished plant bug include malathion, Assail®, Brigade®, Bifenture®, Danitol®, and PyGanic®.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Two-spotted spider mites have been over threshold in several fields this week, which is to be expected under prolonged warm, dry conditions. It is important to scout for mites regularly, as they can build up very rapidly. If 25% of leaves sampled  (e.g. 15 out of 60) have any mites, a spray should be applied. Chemical control options for two-spotted spider mites include Acramite®, Savey®, Zeal®, Vendex®, Oberon®, Brigade®, and Danitol®.  Be sure to use enough liquid and pressure in the spray to get good coverage on the undersides of the leaves.

Diseases: Fields in southern Maine are getting ready for a second application of fungicide to prevent gray mold, in anticipation of weekend rains, which could result in fungal spores being released to infect remaining flowers. Two to three sprays of fungicide are typically required to provide good protection. The first spray is usually applied at 5-10% bloom, followed by a second application at petal fall.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                       Pest Management
P.O. Box 179                             491 College Avenue
Monmouth, ME  04259         Orono, ME  04473
207.933.2100                           1.800.287.0279

Maine Cooperative Extension, the Land Grant University of the state of Maine and the U.S. Department of Agriculture Cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.  A Member of the University of Maine System.

Where brand names or company names are used it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

 

 

 

 

Strawberry IPM Newsletter No. 2 – May 27, 2016

Monday, June 20th, 2016

StrawberriesStrawberry IPM Newsletter No. 2 – May 27, 2016
Click on photos to enlarge.

STRAWBERRY PESTS ENJOYING EARLY BLOOMING FIELDS

Clippers, and Spider Mites Over Threshold this Week

Vegetable and Berry Growers Twilight Meeting
Thursday, June 9, 2016 at 4:00 p.m.
McDougal’s Orchard in Springvale, Maine

Situation:
While dry weather this spring may reduce worries about gray mold pressure, it is also a concern for fields that have experienced winter injury.  Winter injury damages the plants vascular system, reducing the plants ability to take up water. Dry conditions make this problem worse as injured plants become drought stressed.  To ease the effects of winter injury, make sure the plants are getting plenty of water; through irrigation if rainfall is lacking. Once fruit have started to develop, strawberry plants should receive one to two inches of water per week. Early varieties are now in bloom in southern Maine, while later varieties have flower buds emerging from the crowns.

Twilight Meeting
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a twilight meeting at McDougal’s Orchard in Springvale on Thursday, June 9 at 4:00 p.m. This will be a joint meeting with the Maine State Pomological Society.  Trevor Hardy of Brookdale Farm will be on hand to discuss the latest developments in irrigation equipment for fruit and vegetable growers, and George Hamilton from the University of New Hampshire will be there to talk about good sprayer calibration. We will have an opportunity to tour some of the orchard and berry plantings at the farm, courtesy of Ellen and Jack McAdam, and see some of the new deer-control fencing installed with the help of a federal program.  In addition, we’ll discuss the upcoming season and pest management issues facing vegetable and berry growers this year.  We anticipate that one pesticide applicator recertification credit will be awarded for the meeting. Hold the date! McDougal Orchard is located at 201 Hanson Ridge Road in Springvale Maine.  You can visit their website at:  http://www.mcdougalorchards.com/index.php.

Clipper Injury

Clipper Injury, Photo by David Handley

Strawberry bud weevil or “clipper” is active in most of the fields we’ve scouted. We are seeing feeding signs on open flowers and clipped buds on early blooming varieties. We expect clippers to become more prevalent as later varieties start coming into bloom. You should start scouting your fields for clipped buds now. Insecticide options for clipper include Lorsban®, Brigade®, Bifenture®, Danitol®, Sevin® and PyGanic®.

Tarnished plant bug activity has been fairly low so far this season.  We have seen adults in some fields, and found nymphs in about half of the fields, in one case over the spray threshold. The nymphs can be hard to find, especially if the plants are wet. Young nymphs are very small (2 mm), active, yellow-green insects.  It is important to scout for them regularly, as they can appear very quickly. The threshold for nymphs is 4 or more flower clusters infested per 30 sampled. Start scouting any field with open flowers now.  Insecticide options for tarnished plant bug include malathion, Assail®, Brigade®, Bifenture®, Danitol®, and PyGanic®.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Two-spotted spider mites have been found in most fields this week, but were over threshold only in one field where row covers had been used. Mites typically proliferate under hot, dry conditions, and we often first find them in plantings under row covers.  But any plantings that harbored a high mite population last fall are also likely to see a problem with mites this spring. It is important to scout for mites regularly. If 25% of leaves sampled  (e.g. 15 out of 60) have any mites, a spray should be applied. Chemical control options for two-spotted spider mites include Acramite®, Savey®, Zeal®, Vendex®, Oberon®, Brigade®, Danitol®, Thionex® and JMS Stylet oil® (oils will cause plant injury if used in combination with captan or within 14 days of an application of sulfur).  Be sure to use enough liquid and pressure in the spray to get good coverage on the undersides of the leaves.

Cyclamen mites:  We have seen three fields with light symptoms of cyclamen mite injury this week. Infested plants show weak growth and shrunken, crinkled leaves. These mites are very small and reside in the crown of the strawberry plant, feeding on the developing leaves and flower buds. They are very hard to see, even with magnification. Portal®, Kelthane® or Thionex® can be effective, but must be applied in lots of water to be sure that the material is carried down into the crowns where these mites reside. Thionex® will no longer be available for use on strawberries after July of 2016.

White grubs: Grubs have been found in some fields this spring. Infested plants are stunted and often wilt during the heat of the day. These grubs are the larvae of Japanese beetle, European chafer and Asiatic garden beetle. They have legs and a swollen anterior (rear end). Admire Pro® can be applied for control of white grubs in the spring. It should be applied within two hours of irrigation or rainfall to be sure the chemical gets into the root zone, and it requires a 14-day pre-harvest interval.

Diseases: As the fields come into bloom it is time to protect the flowers against infection by spores of the gray mold fungus, Botrytis cinerea. Fruit infections take place through the flowers, so gray mold control efforts must be focused on the bloom period. Two to three sprays of fungicide are typically required to provide good protection. The first spray is usually applied at 5-10% bloom, followed by a second application at petal fall. Additional applications may be applied if there is significant rainfall between or following these two sprays.

Leather rot (Phytopthora cactorum) may become a problem in fields where standing water is common during bloom and fruit development, especially if the fields were not mulched last fall. Incidence of leather rot can be reduced by applying straw mulch between the rows to prevent berries from touching the soil and reducing soil splashing onto the berries. Foliar sprays of Aliette®, Agri-Phos® or Phostrol® may be applied during bloom and fruit development to prevent leather rot when there has been excess moisture in a field, especially those with a history of this problem.

Powdery mildew:  We have not yet seen symptoms of this fungus disease in fields. It tends to be more prevalent under warm, humid conditions. It may first appear as purple or red blotches on the leaf and flower stems. Later, upward curling leaves and white, powdery growth on the undersides of the leaves becomes evident. Check your fields for pinkish purple leaf and flower stem lesions as new leaves emerge. Pristine®, Cabrio®, Topsin-M®, captan, Procure®, Torino® and JMS Stylet oil® are registered to control powdery mildew.

Angular Leaf Spot

Bacterial Angular Leaf Spot, Photo by David Handley

Angular leaf spot is a bacterial disease characterized by small water-soaked spots on the leaves, which may turn yellow or black. The symptoms start on the lower leaves but spread throughout the foliage when spores are splashed up by rain or irrigation water. Infections can cause blackening of the berry stems and caps. This disease is favored by extended cool, wet weather with night temperatures close to freezing. Irrigating fields for frost protection encourages development and spread of the disease. Hydrogen dioxide (OxiDate®) may have some activity against angular leaf spot when used on strawberries as part of a gray mold management program.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                       Pest Management
P.O. Box 179                             491 College Avenue
Monmouth, ME  04259          Orono, ME  04473
207.933.2100                            1.800.287.0279

Maine Cooperative Extension, the Land Grant University of the state of Maine and the U.S. Department of Agriculture Cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.  A Member of the University of Maine System.

Where brand names or company names are used it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.