Archive for the ‘News’ Category

Sweet Corn IPM Nesletter No. 4 – July 20, 2018

Friday, July 20th, 2018

Sweet CornSweet Corn IPM Newsletter No. 4 – July 20, 2018
Click on photos to enlarge.

LOW INSECT ACTIVITY CONTINUES

Storms Expected Next Week May Bring Pests into Maine

SITUATION
Some welcome rain fell on dry corn fields this week, followed by more warm weather. As a result, we are seeing rapid corn development in the fields. Early harvest has begun in some transplanted and mulched fields. Corn pest activity continues to be very low in cornfields this week, so very few fields have needed sprays. Weather predictions for the coming week indicate warm air and moisture coming up from the south, which may bring in significant numbers of corn earworm and fall armyworm.

European corn borer:  There was very little borer activity in both pheromone traps and fields this week. Moths were only caught in three locations: Cape Elizabeth, Dayton and Wales. They were below threshold for silking corn at all of these sites. Feeding damage was also light, with only one field in Oxford being over the 15% spray threshold for pre-tassel to silking corn.

Corn earworm:  No moths were caught in our pheromone traps this week, and therefore no sprays were recommended. There is more silking corn available for earworm moths to lay eggs on this week, so the threat is increasing. Growers should be alert for changes in the weather, such as storms moving in from southern states, that could bring more corn earworm into Maine.

Fall armyworm:  No moths were caught in our pheromone traps this week, and we have not yet found any feeding damage in the cornfields we’ve scouted. We have found a few common armyworms within corn plants behaving much like fall armyworm. However, these larvae will be pupating very soon and are not likely to get into the ears. Like corn earworm, the situation for fall armyworm could change rapidly with weather coming up from the south next week.

Squash Vine Borer Larva

Squash Vine Borer Larva, photo by David Handley

Japanese Beetle

Japanese Beetle, photo by Edwin Remsberg, USDA

Squash vine borer moths were caught in pheromone traps in Biddeford, New Gloucester, Lewiston, Nobleboro, Farmington and Oxford this week. Only the Oxford site, which had 11 moths, was over the 5-moth spray threshold. All other sites were below the spray threshold, but we expect counts to increase state wide in the coming days. Growers with squash in southern Maine should be scouting for vine borer symptoms and protect squash plants if moths or damage are seen. See the 2018-2019 New England Vegetable Management Guide for control options.

Japanese beetles are now appearing in southern and mid-state areas. These insects often find their way into cornfields and feed on the leaves, causing an interveinal skeletonizing, which is generally not significant. However, they may also feed on the silks of developing ears, causing poor tip fill. Sprays for European corn borer and/or corn earworm (except Bt’s) usually will control Japanese beetle as well.

Spotted wing drosophila:  The first capture of spotted wing drosophila (SWD) occurred this week in berry fields in southern Maine. These small fruit flies can cause serious fruit losses in raspberries, blueberries and other soft fruits. This pest has already reached damaging numbers throughout much of New England, which is about 2-3 weeks ahead of what we have seen in the past few years.  For more information visit our SWD blog.

Male and Female Spotted Wing Drosophila Flies

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

 

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Biddeford 0 0 0 9% No spray recommended
Bowdoinham 0 0 0 1% No spray recommended
Cape Elizabeth I 0 3 0 0% No spray recommended
Cape Elizabeth II 0 0 0 6% No spray recommended
Dayton 0 3 0 0% No spray recommended
Farmington 0 0 0 9% No spray recommended
Lewiston I 0 0 0 0% No spray recommended
Lewiston II 0 0 0 0% No spray recommended
Nobleboro 0 0 0 No spray recommended
No. Berwick 0 0 0 0% No spray recommended
Oxford 0 0 0 19% One spray recommended for ECB feeding damage
Sabattus 0 0 0 11% No spray recommended
Wales 0 1 0 0% No spray recommended
Wayne 0 0 0 4% No spray recommended
Wells I 0 0 0 4% No spray recommended
Wells II 0 0 0 0% No spray recommended

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB: European corn borer
FAW: Fall armyworm

Corn Earworm Spray Thresholds for Pheromone Traps

Moths caught per week Moths caught per night Spray interval
0.0 to 1.4 0.0 to 0.2 No spray
1.5 to 3.5 0.3 to 0.5 Spray every 6 days
3.6 to 7.0 0.6 to 1.0 Spray every 5 days
7.1 to 91 1.1 to 13.0 Spray every 4 days
More than 91 More than 13 Spray every 3 days

Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.

European Corn Borer Thresholds
Whorl stage: 30% or more of plants scouted show injury.
Pre-tassel-silk: 15% or more of plants scouted show injury.
Silk: 5 or more moths caught in pheromone traps in one week.

IPM Web Pages:

UMaine Cooperative Extension Integrated Pest Management
PennState Pestwatch for Sweet Corn
UMass Amherst Integrated Pest Management

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.

Sweet Corn IPM Newsletter No. 3 – July 13, 2018

Friday, July 13th, 2018

Sweet CornSweet Corn IPM Newsletter No. 3 – July 13, 2018
Click on photos to enlarge.

LOW INSECT ACTIVITY IN CORNFIELDS

Few Moths or Damage Found This Week

SITUATION
Warm, dry weather continues to move corn development rapidly throughout the state, and many early fields are or will be silking within the next few days. Adequate irrigation is key to good ear fill during the silking stage if rainfall has been lacking. Drought stressed corn will often have very poor ear size and fill.  Insect activity in cornfields was very low this week, perhaps related to cooler nighttime temperatures.

European corn borer:  Very few moths were caught in pheromone traps this week, and only along the southern coast. Larval feeding damage was also below threshold in all fields scouted, as sprays applied over the past week have cleaned up fields that were recently over threshold. Some early fields are now silking, and when corn reaches that stage, sprays can be based on the number of corn borer moths caught in pheromone traps rather than feeding injury. However, none of our sites exceeded the 5 moth per week spray threshold.

Corn earworm:  A single moth was caught in a pheromone trap in Lewiston this week. A spray was not recommended, even when some silking corn was present. Once more than one moth per week is captured in a silking field, a spray interval will be recommended, based on the number of moths being caught. There is still not much silking corn available for earworm moths to lay eggs on, so the threat remains low. Warmer evening temperatures and any weather fronts moving into Maine from the south could change the situation rapidly; although, as of this week, low earworm activity is also being reported from states to our south.

Two Squash Vine Borer Moths

Two Squash Vine Borer Moths, photo by Jeffrey Hahn, Univ. of Minnesota Extension

Fall armyworm:  No moths were caught in our pheromone traps this week, and we have not yet found any feeding damage in the cornfields we’ve scouted. As with corn earworm, however, this situation could change rapidly if weather fronts from the south move into the state.

Squash vine borer moths were caught in pheromone traps in Biddeford, Lewiston and Oxford this week. Counts were below the spray threshold, but indicate that this pest will threaten squash and pumpkins this season. Moth counts in New Hampshire are over threshold this week, so activity here will rise soon. Squash vine borer moths are black and orange and resemble wasps. They lay their eggs at the base of squash plants. The larvae bore into the base of the plants, causing vines to wilt and collapse. Growers with squash in southern Maine should be on the lookout for vine borer symptoms and protect squash plants if moths or damage are seen. See the 2018-2019 New England Vegetable Management Guide for control options.

Potato Leafhopper

Potato Leafhopper, photo by James Dill

Potato leafhopper alert:  potato leafhopper is now active in vegetable and strawberry fields. These small, bullet-shaped insects feed on plant sap from the undersides of leaves, causing the leaves to become curled, stunted and yellow-streaked. Beans are often the first crop to show symptoms, but other crops are also susceptible, including potatoes and strawberries. To scout for leafhoppers, brush the leaves of the plants with your hand. The small, whitish adults can be seen flying off the plant. Look for small, light green leafhopper nymphs on the underside of injured leaves. They are about 1/16-inch long. When touched, they will crawl sideways in a crab-like manner. Control options for potato leafhoppers are listed in the New England Vegetable Management Guide.

Maine State Pomological Society Summer Tour
The event will be held on Wednesday July 18, 2018 at Dole’s Orchard, 187 Doles Ridge Road, Limington, Maine 04048. Earl and Nancy Bunting will be hosting the Maine State Pomological Society Summer Tour at their farm this summer. Much of the focus will be on the tree fruit grown at Dole’s Orchard, including apples and cherries; but there are also large plantings of pic-your-own strawberries, raspberries and blueberries. Some of the fruit is also contracted to a local brewery. There will be a morning educational program, including talks from research and Extension Specialists, followed by lunch and afternoon tours of the fields and orchards led by Earl and Nancy. Plan to come visit this beautiful farm with us! Pre-registration is requested so we know how many lunches to request. Please contact Pam St. Peter at 207.933.2100 or pamela.stpeter@maine.edu for more information.

Two pesticide applicator credits will be offered for attending the summer tour’s full day program. Registration is $15 for Maine State Pomological Society members, and $20 for nonmembers. Registration payments by cash or check will be collected at the event.

Cornfield at Highmoor Farm

Cornfield at Highmoor Farm, photo by David Handley

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Biddeford 0 1 0 0% No spray recommended
Cape Elizabeth I 0 3 0 0% No spray recommended
Cape Elizabeth II 0 0 0 4% No spray recommended
Dayton I 0 0 0 6% No spray recommended
Farmington 0 0 0 13% No spray recommended
Lewiston I 0 0 0 0% No spray recommended
Lewiston II 1 0 0 0% No spray recommended (no silking corn)
New Gloucester 0 0 0 0% No spray recommended
Nobleboro 0 0 0 0% No spray recommended
No. Berwick 0 0 0 1% No spray recommended
Oxford 0 0 0 12% No spray recommended
Wales 0 0 0 0% No spray recommended
Wayne 0 0% No spray recommended
Wells I 0 0 0 4% No spray recommended
Wells II 0 0 0 0% No spray recommended

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB: European corn borer
FAW: Fall armyworm

Corn Earworm Spray Thresholds for Pheromone Traps

Moths caught per week Moths caught per night Spray interval
0.0 to 1.4 0.0 to 0.2 No spray
1.5 to 3.5 0.3 to 0.5 Spray every 6 days
3.6 to 7.0 0.6 to 1.0 Spray every 5 days
7.1 to 91 1.1 to 13.0 Spray every 4 days
More than 91 More than 13 Spray every 3 days

Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.

European Corn Borer Thresholds
Whorl stage: 30% or more of plants scouted show injury.
Pre-tassel-silk: 15% or more of plants scouted show injury.
Silk: 5 or more moths caught in pheromone traps in one week.

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
https://ag.umass.edu/integrated-pest-management/

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. 6 – July 9, 2018

Monday, July 9th, 2018

StrawberriesStrawberry IPM Newsletter No. 6 – July 9, 2018
Click on photos to enlarge.

RENOVATION AND WEED MANAGEMENT ISSUE

Get Your Strawberry Beds Ready for Next Year

Manage Pests in Day-Neutral Strawberries

A mostly dry spring and warm temperatures led to a somewhat early start, but intense heat as the berries ripened significantly shortened the harvest season for many growers, and may have kept many PYO customers from coming out. A second very dry summer last year also left many beds with thinner plant populations than normal this spring, due to a lack of good runner growth. Pest pressure however, was relatively light in most fields. Spider mites and cyclamen mites were the most common problem across the state. We have seen a lot of Asiatic garden beetles flying around this summer, so growers should be on the lookout for white grub damage, especially in new plantings. (See white grub note below.) Disease pressure was also light in most fields, with leaf spot being the most common problem. A few late rain showers triggered the need for one to three fungicide treatments to keep gray mold to a minimum. Deer and turkeys did some damage to plants over the winter in several fields. All in all, the harvest was good; quantity and quality very good, with berry size down a bit, similar to last year, due to 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.

Leaf Spot

Leaf Spot, 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 for many seasons, and in fields that have been stressed 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.

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 the spring and again in late July through August. We did find adults in many fields while we were scouting during bloom this spring. 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 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, and may look like herbicide damage. 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 on Strawberry Plant

Cyclamen Mite Damage on Strawberry Plant, 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 often become a big problem during the summer because they are 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 help 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 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.
  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®, Satellite Hydrocap®): 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. Satellite Hydrocap® may also be applied at renovation, but before new growth begins.

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®).
Mowing Strawberry Leaves

Mowing Strawberry Leaves, photo by David Handley

  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.
  1. 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.
  1. 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.
Strawberry Irrigation

Strawberry Irrigation, photo by David Handley

  1. 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, Rm. 407, University of Maine, Orono, Maine 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 Spotted Wing Drosophila

Male Spotted Wing Drosophila, photo by Griffin Dill. Actual size: 2-3 mm.

Spotted wing drosophila (Drosophila suzukii) 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. 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 on Strawberry

Tarnished Plant Bug on Strawberry Flower, photo by David Handley

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.

Gray Mold on Strawberries

Gray Mold on Strawberries, photo by James Dill

Powdery Mildew

Powdery Mildew, photo by David Handley

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

HOLD THE DATE:

Strawberry Production Workshop
A strawberry workshop will be offered on Thursday January 17, 2019 at the Augusta Civic Center, concurrent with the Maine Agricultural Trades Show, January 15-17, 2019. Details and registration will be available this 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

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.


 

Sweet Corn IPM Newsletter No. 2 – July 6, 2018

Friday, July 6th, 2018

Sweet CornSweet Corn IPM Newsletter No. 2 – July 6, 2018
Click on photos to enlarge.

CORN EARWORM THREATENS EARLY SILKING CORN

European Corn Borer Damage on the Rise

SITUATION
A string of very hot, humid days has pushed corn development along rapidly, especially in irrigated fields.  Hail ripped up young corn in a few fields, but young corn is likely to recover from the damage. Transplanted corn and some seeded under plastic mulch is silking in southern Maine, indicating that the start of harvest could be only two to three weeks away. The hot weather has also stimulated more insect activity, as we have found a couple of fields over threshold for European corn borer damage, and a couple of early corn earworm moths in traps along the coast.

European Corn Borer Moth

European Corn Borer Moth, photo by David Handley

European corn borer:  Moths were caught in pheromone traps in southern and coastal sites this week, and larval feeding damage is showing up on whorl to tassel stage corn. In whorl stage corn the control threshold is 30% of plants showing feeding injury. Once the plants reach the pre-tassel stage the threshold is lowered to 15%, because larvae at this stage are more likely to damage the ears. Pre-tassel fields in Biddeford, Bowdoinham and Dayton were over control threshold for pre-tassel corn, so sprays were recommended. Sprays during the pre-tassel stage, when both moths and larvae are present, target the larvae before can they move into the protection of the stalks and ears. Once corn reaches the silk stage, sprays may be based on the number of corn borer moths caught in pheromone traps rather than feeding injury. If more than 5 moths are caught in pheromone traps in a week near silking corn, a spray is recommended to prevent moths from laying eggs on the flag leaves of the ears, which could lead to larvae infesting the ears while leaving no visible signs of feeding on the leaves. So far, none of the silking fields have been over the 5-moth threshold.

Corn earworm:  Moths were caught in pheromone traps at two coastal locations, Cape Elizabeth and Nobleboro. Both of these captures were single moths, which does not trigger a spray, even if silking corn is present. Once more than one moth per week is captured in a silking field, a spray interval would be recommended, based on the number of moths being caught. The more moths caught, the more frequently the silking corn will need to be sprayed to adequately protect it. (See table below.) At present, there is very little silking corn available for earworm moths to lay eggs on, so the threat is low for most fields. When no silking corn is available, corn earworm moths may lay eggs on corn leaves, and the larvae will chew large, ragged holes in the leaves, similar to fall armyworm.

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Male Fall Armyworm Moth

Male Fall Armyworm Moth, photo by David Handley

Fall armyworm:  No moths have been captured in our pheromone traps this week, and no feeding damage has been reported. Although this is usually the last major corn pest to arrive in Maine from southern overwintering sites, it often follows corn earworm closely, and was the most significant pest problem in most corn fields for the past two seasons.

Common armyworm is often found chewing on early corn. Like fall armyworm, this caterpillar chews large holes in whorl to pre-tassel corn. The larvae are light brown with yellow and black stripes running along the body. This insect overwinters in Maine and is usually only present early in the season. Young corn can often outgrow the injury. However, heavy infestations can occur and may require control. We have found some common armyworm in western Maine this week, but not at significant levels.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Biddeford 0 1 0 23% One spray for ECB on pre-tassel corn
Bowdoinham 0 0 0 15% One spray for ECB on pre-tassel corn
Cape Elizabeth I 0 3 0 4% No spray recommended
Cape Elizabeth II 1 4 0 4% No spray recommended (corn not yet silking)
Dayton I Set up Set up Set up 16% One spray for ECB on pre-tassel to silking corn
Farmington 0 0 0 0% No spray recommended
Lewiston I 0 0 0 4% No spray recommended
Lewiston II Set up Set up Set up 0% No spray recommended
New Gloucester 0 0 0 0% No spray recommended
Nobleboro 1 2 0 13% No spray recommended
No. Berwick Set up Set up Set up 14% No spray recommended
Oxford 0 0 0 15% One spray for ECB on pre-tassel corn
Wayne 0 0 0 0% No spray recommended
Wells I Set up Set up Set up 0% No spray recommended
Wells II Set up Set up Set up 0% No spray recommended

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB: European corn borer
FAW: Fall armyworm

Corn Earworm Spray Thresholds for Pheromone Traps

Moths caught per week Moths caught per night Spray interval
0.0 to 1.4 0.0 to 0.2 No spray
1.5 to 3.5 0.3 to 0.5 Spray every 6 days
3.6 to 7.0 0.6 to 1.0 Spray every 5 days
7.1 to 91 1.1 to 13.0 Spray every 4 days
More than 91 More than 13 Spray every 3 days

Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.

European Corn Borer Thresholds
Whorl stage: 30% or more of plants scouted show injury.
Pre-tassel-silk: 15% or more of plants scouted show injury.
Silk: 5 or more moths caught in pheromone traps in one week.

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
https://ag.umass.edu/integrated-pest-management/

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.

Sweet Corn IPM Newsletter No. 1 – June 29, 2018

Friday, June 29th, 2018

Sweet CornSweet Corn IPM Newsletter No. 1 – June 29, 2018
Click on photos to enlarge.

2018 SWEET CORN PEST SEASON BEGINS!

European Corn Borer Active in Early Fields

The 2018 University of Maine Cooperative Extension Integrated Pest Management (IPM) program for sweet corn is underway. More than twenty volunteer farms are serving as pest monitoring and demonstration sites, with fields in North Berwick, Wells, Dayton, Cape Elizabeth, New Gloucester, Poland Spring, Auburn, Lewiston, Sabattus, Nobleboro, Monmouth, Wales, Wayne, Oxford, Farmington, Levant, Stillwater, Garland and East Corinth. We are setting up pheromone traps at these locations to monitor the adult (moth) stages of European corn borer, corn earworm and fall armyworm, and we are scouting the fields for feeding injury by insect larvae. We will be sharing the information we collect along with management recommendations through this newsletter blog.

SITUATION
A very dry spring has got early corn off to a quick start, in spite of variable temperatures. Early plantings in southern Maine and plots started under plastic or row covers are mostly at pre-tassel, although we have seen a few tassels, and some silking corn in a transplanted field. Late fields are starting to emerge. Early scouting has shown some European corn borer activity in pre-tassel corn, but no damage has been over the spray threshold. With warmer temperatures expected we can expect to see increased activity in the coming days, and weather coming up from the south may also bring our first corn earworm of the season.

European corn borer:  Pheromone traps for moths are set up in the grassy borders around cornfields. We have begun scouting pre-tassel to tasseling fields in southern Maine, and found some early feeding damage in Oxford, Farmington, Wayne and Nobleboro. To monitor corn borer, we scout 100 corn plants in each field, examining twenty plants in a row at five different locations. This provides a good estimate of the total amount of injury in a field.

European Corn Borer Moth

European Corn Borer Moth, photo by David Handley

European Corn Borer Damage

European Corn Borer Damage, photo by David Handley

In the early stages, European corn borer feeding damage looks like small “pinholes” in the leaves. Whorl stage corn only needs to be sprayed if fresh feeding injury is found on 30% or more of the plants scouted in a field. Once the corn reaches the pre-tassel stage, the control threshold is lowered to 15% because larvae feeding on the later stages are more likely to move into the ears. On the tassels, feeding damage first appears as chewing and brown waste found in the small florets. After the tassel has emerged from the whorl, the larvae chew into the stalk just below it, often causing the tassel to fall over. Sprays during the pre-tassel stage, when both moths and larvae are present, target the larvae before can they move into the protection of the stalks and ears. Good spray coverage of the entire plant provides the most effective kill of larvae as they move from one part of the plant to another. Rotating the type of insecticide used also improves control. Materials registered for controlling European corn borer include Bacillus thuringiensis products (XenTari®, Dipel DF®), Avaunt®, Coragen®, Warrior®, Lannate®, Baythroid®, Asana®, Radiant®, Delta Gold®, Mustang®, Sevin XLR® and Intrepid®. Newly hatched European corn borer larvae are very small and translucent with shiny black heads. They emerge from small egg masses that look like a tiny clump of overlapping fish scales on the undersides of corn leaves. European corn borer overwinters in Maine, and is usually the first pest to become a significant problem.

Growers should start scouting whorl stage corn for feeding injury now. Once corn reaches the silk stage, sprays may be based on the number of corn borer moths caught in pheromone traps rather than feeding injury. European corn borer moths will lay eggs on flag leaves of silking corn, and the larvae can move into the ears without leaving visible feeding injury that would be noticed when scouting. If more than five moths are caught during a week in a field with silking corn, a spray is recommended. Varieties of corn genetically modified to produce the Bt toxin (e.g. Bt corn, Attribute® varieties), should not need to be sprayed to control European corn borer.

Corn earworm:  We have set up pheromone traps around the state for corn earworm moths. Corn earworm generally appears in Maine in early July, but the actual date varies greatly. The arrival of this pest is only a concern for fields with corn in the silk stage. Fields not yet in silk do not need to be protected from corn earworm. When corn earworm moths are caught at a site, all silking corn in the fields should be protected with a spray. These moths lay eggs on the fresh silks, and the larvae move directly into the ears of corn. When corn earworm moths cannot find silking corn to deposit their eggs on, they may lay eggs on the leaves or tassels of younger corn. The larvae will feed on the foliage and tassels, similar to armyworm, until the ears become available. When larvae are found feeding on younger corn, the damage is accounted for, along with any borer or armyworm damage, to determine if a spray is warranted.

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Fall Armyworm Moths

Fall Armyworm Moths (female right, male left), photo by James Dill

Fall armyworm:  This is usually the last serious corn insect pest to arrive in Maine. The moths fly in from southern over-wintering sites, and tend to lay their eggs on the youngest corn available. The young larvae chew large, ragged holes in the leaves, and may bore into developing ears. Larvae can also move into the ears through the silk channel, behaving similarly to corn earworm. Pheromone trap catches will indicate if there is a threat to silking corn. However, corn is often on a spray program for corn earworm when fall armyworm is present, and both insects should be controlled. For the past two years, fall armyworm moths arrived in Maine early in the season, and were often more of a threat than corn earworm. We will be watching fall armyworm closely this year to see if this new, unfortunate trend continues.

Common armyworm:  Be on the lookout for reports of common armyworm attacking silage corn, alfalfa and hayfields. Common armyworm can become active as early as April and can become a problem in early planted sweet corn. However, if the corn is established, it will outgrow the injury, as the caterpillars will pupate before the ears develop. However, when heavy infestations occur, control may be required. Common armyworm larvae are brown with yellow and black stripes running along the body. They chew large, ragged holes in the leaves, similar to fall armyworm.

Northern Corn Leaf Blight

Northern Corn Leaf Blight, photo by David Handley

Northern corn leaf blight:  This fungus disease has become more prevalent across New England in recent years, and growers should monitor fields for the symptoms. Gray to tan cigar-shaped lesions appear on the leaves and stalks, eventually coalescing, causing the leaves to die and dry up. This weakens the plants, reducing yield and quality of the ears. To manage the disease, purchase only varieties that are resistant to leaf blight, rotate out of fields that have had the disease for at least one year, and when necessary apply fungicides when symptoms are first noticed. For more information, including products and rates, consult the New England Vegetable Management Guide.

Do-It-Yourself IPM:  To get the most accurate information about the pest situation on your farm you should monitor the fields yourself on a regular basis. Pheromone traps and lures are available that can give you an accurate, early warning of the arrival of all of the major insect pests. Traps and lures can be purchased from pest management supply companies such as Gempler’s (1.800.382.8473) or Great Lakes IPM (517.268.5693). You may also want to download a copy of our fact sheet Managing Insect Pests of Sweet Corn at our website.

European Corn Borer Trap

European Corn Borer Trap, photo by David Handley

Harstack Trap

Harstack Trap, photo by David Handley

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://ag.umass.edu/integrated-pest-management/umass-extension-programs

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. 5 – June 15, 2018

Monday, June 18th, 2018

StrawberriesStrawberry IPM Newsletter No. 5 – June 15, 2018
Click on photos to enlarge.

HARVEST BEGINS IN SOUTHERN MAINE

Birds Causing Damage on Early Ripening Fruit

Situation:
Strawberry fields have been opening up in southern Maine this week, with growers hoping for a good weekend. The crop looks very good, although the lack of rain this spring may be having an impact on fruit size. Cedar waxwings have been a problem in many fields, pecking and feeding on the first ripe fruit. Hopefully, once pickers start to frequent the fields these birds will cause less damage, but they are very bold and hard to deter (see last week’s issue for more details on managing birds). The Strawberry IPM Newsletter will take the next couple of weeks off and return with the annual renovation issue in July.

Tarnished plant bug populations remain low, with most fields not having any nymphs, but two coastal fields were over the spray threshold of 4 or more flower clusters infested per 30 sampled. Thus, growers should continue scouting for tarnished plant bug, especially in later ripening varieties, until the green fruit start to swell.

Sap beetle on strawberry

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

Sap beetles:  Growers should keep an eye out for sap beetle 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.

Two-spotted spider mite:  Although we are finding mites in many of the fields we are scouting, most fall below the control threshold of 25% of leaves being infested. If dry weather continues to dominate, mites will likely continue to be a problem in strawberries. However, bed renovation just after harvest and the few weeks following are a good time to manage mites, as both miticides and/or predatory mites can be very effective then.

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 some 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.

Strawberry Harvest

Strawberry Harvest, photo by David Handley

  • 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.
  • 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.

Hold the Date!

Maine State Pomological Society Summer Tour on Wednesday July 18, 2018, at Dole’s Orchard in Limington.

Earl and Nancy Bunting will be hosting the Maine State Pomological Society Summer Tour at their farm this summer. Much of the focus will be on the tree fruit grown at Dole’s orchard, including apples and cherries, but there are also large plantings of pick-your-own strawberries, raspberries and blueberries.  Some of the fruit is also contracted to a local brewery. There will be a morning educational program, including talks from research and Extension Specialists, followed by lunch and afternoon tours of the fields and orchards led by Earl and Nancy. Plan to come visit this beautiful farm with us! Pre-registration is requested so we know how many lunches to request. Please contact Renae Moran or Pam St. Peter at 207.933.2100 or pamela.stpeter@maine.edu for more information.

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 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. 4 – June 8, 2018

Friday, June 8th, 2018

StrawberriesStrawberry IPM Newsletter No. 4 – June 8, 2018
Click on photos to enlarge.

EARLY STRAWBERRY FIELDS HARVESTING SOON

Insect and Mite Counts Generally Low, but Fruit Rots Still a Threat

Situation:
A little helpful rain has fallen in most parts of the state this week, but most fields are still quite dry. A few ripe strawberries are now appearing in southern Maine in fields that used row covers this spring. We had a good crowd at the berry and vegetable twilight meeting at Pineland farms this week. Despite a passing shower, participants got a tour of the operation, including over 20 acres of strawberries, and were treated to a few early ripe “Wendy” strawberries from the field.  Thanks to Justin Gray, Manager of Pineland’s Produce Division and his crew for being great hosts of this event.

Strawberry bud weevil or “clipper”:  Although we have found a few live clippers this week, most fields in southern Maine are beyond the stage when this insect can cause significant injury, except on very late-blooming varieties such as “Malwina” and perhaps “Valley Sunset”. Growers in more northern areas with plants still in the early bloom stage should remain on the lookout for clipped buds.

Tarnished plant bug activity continues to be spotty around the state this week. Nymphs were only found in a few fields and under the spray threshold of 4 or more flower clusters infested with nymphs per 30 sampled. Cold temperatures have likely slowed the emergence of this insect, and populations could rise quickly once temperatures rise. Growers should continue scouting for tarnished plant bug until the green fruit start to swell.

Two-spotted spider mite:  We are finding mites in most fields we are scouting, but with cooler temperatures and control efforts by growers, the numbers have been quite low, well below the spray threshold of 25% of leaves infested. Only one site in Bowdoinham had mite numbers over the recommended spray threshold. Mite populations can increase rapidly under warm, dry conditions, so it is important to continue scouting for them through the season.

Black Vine Weevil

Black Vine Weevil, photo by David Handley

Strawberry Root Weevil Grub

Strawberry Root Weevil Grub, photo by David Handley

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 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.

Diseases:  Late blooming varieties may still need protection against infection from Botrytis gray mold spores, especially if there is any wet weather predicted for your area. Two to three bloom sprays typically offer the best protection against this fruit rot, beginning at early bloom and ending at petal fall or just after, unless prolonged wet weather necessitates additional sprays to assure the blossoms are protected.

Leaf Spot on Strawberry Plant

Leaf Spot, photo by David Handley

Leaf diseases:  Powdery mildew has not yet been a problem in fields that we have scouted this spring, but growers should continue to be on the lookout for symptoms of upward cupping of the leaves and reddish streaking or lesions on the leaf and flower stems. If you see powdery mildew in the field, consider using a fungicide that offers control of it, such as captan + Topsin-M®, or Pristine® if you’re still spraying for gray mold.

Leaf spot is becoming more noticeable on susceptible varieties. Small reddish-purple spots with white centers appear on the leaves, often first on the inner part of the plant canopy. They may also appear on the leaf and flower stems. Severe infections weaken plants, and can reduce fruit size, yield, and quality. If you see leaf spot in your field, you should apply 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.

Bird Damage on Strawberry

Bird Damage on Strawberry, photo by David Handley

Birds, especially cedar waxwings, will soon be moving into fields to feed on ripe fruit. Where wax wings are a problem, only keeping a near constant presence in the field and eliminating roosting sites can 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.

On-farm readiness reviews for Food Safety Modernization Act Produce Safety Rule inspections
On-farm readiness reviews are non-regulatory, free assessments of a farm’s readiness for inspection under the Food Modernization Act Produce Rule. This is a chance for you to have a conversation and walk around your farm with Produce Safety Rule experts to evaluate farm facilities and practices, and assess what you’re doing well, and identify areas for improvement in food safety practices on your farm. These reviews are meant to help farmers understand the new regulations and are not an audit or inspection. No notes or records will be taken off the farm. Before asking for a review, it is recommended that at least one person from your farm complete the Produce Safety Alliance Grower Training course.  You can contact the Maine Department of Agriculture, Conservation and Forestry for information about upcoming trainings. To sign up for an On-Farm Readiness Review (OFRR), you can call 207.764.2100 and ask to be put on the OFRR list. For more information, you can contact Linda Titus at AgMatters LLC (207.631.3303), or Dr. Robson Machado at the University of Maine Cooperative Extension (207.581.3144).

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.

Berry Growers Twilight Meeting – June 6, 2018

Monday, June 4th, 2018

BERRY GROWERS TWILIGHT MEETING AT PINELAND FARMS

Wednesday, June 6, 2018
5:00 p.m. to 7:00 p.m.
Pineland Farms Produce Division, New Gloucester, Maine 04260
Farm Tel. 207.657.2877
Cost:  Free
No registration is required.

The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a twilight meeting for commercial growers at Pineland Farms Produce Division in New Gloucester on Wednesday, June 6, 2018 from 5:00 p.m. to 7:00 p.m.

Pineland Farms has some of the largest strawberry fields in the state, all of which are irrigated. They also have significant plantings of raspberries and high bush blueberries. Their main crops, in addition to strawberries, are sweet corn (which is mechanically harvested) and pumpkins. Join us for a tour with manager, Justin Gray, and a chance to look at some of the equipment and irrigation engineering used at this unique farm. We will also have an update on the berry pest situation around the state.

Pineland Farms is located at 752 Mayall Road in New Gloucester, Maine 04260. The farm phone number is 207.657.2877. One pesticide applicator recertification credit will be awarded for attending the meeting. Cost for the meeting is free and no registration is required. For more information, please contact David Handley at david.handley@maine.edu or 207.933.2100. We hope to see you there!

Directions to 752 Mayall Road in New Gloucester:

Traveling North on I-95:  Take the Gray/New Gloucester Exit 63 onto Route 202. Travel about 2.5 miles, then turn left onto Mayall Road. Continue on Mayall Road about 2 miles; Pineland Farms Produce Division is on the left.

Traveling South on I-95:  Take the Auburn Exit 75 onto Route 202. Travel about 9 miles then turn right onto Mayall Road. Continue on Mayall Road about 2 miles; Pineland Farms Produce Division is on the left.

Any person with a disability who needs accommodations for this program should contact Pam St. Peter at 207.933.2100 to discuss any needed arrangements. Receiving requests for accommodations at least 10 days before the program provides a reasonable amount of time to meet the request; however, all requests will be considered.

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

Strawberry IPM Newsletter No. 3 – June 1, 2018

Friday, June 1st, 2018

StrawberriesStrawberry IPM Newsletter No. 3 – June 1, 2018
Click on photos to enlarge.

MITES AND TARNISHED PLANT BUG NUMBERS RISING

Predicted Rains May Call for Protection Against Gray Mold Infection

Berry Growers Twilight Meeting
Wednesday, June 6, 2018 at 5:00 p.m.
Pineland Farm in New Gloucester, Maine

Situation:
Many parts of the state are very dry for this time of year. While this will help reduce fungal disease infections, it is important to remember that fruit size can be negatively affected by a lack of moisture. As fruit are developing, the plants need one to two inches of water per week to prevent plant stress and assure good fruit size. If the weather is not providing this moisture, growers should irrigate to supply it. It is best to irrigate in the morning so that the plants have time to dry off before evening. This will reduce the chance of fungal diseases taking advantage of the wet conditions. Early fields in southern Maine have green fruit, with the seeds just starting to separate. Later fields are just coming into full bloom. Growers are getting ready to apply their second or third fungicide spray for gray mold before the predicted wet weather this weekend.

Strawberry Irrigation

Strawberry Irrigation, photo by David Handley

Reminder:  Twilight Meeting Wednesday June 6th, Pineland Farm, 752 Mayall Road, New Gloucester, Maine 04260. Pineland Farms has some of the largest strawberry fields in the state, all of which are irrigated. They also have significant plantings of raspberries and high bush blueberries. Their main crops, in addition to strawberries, are sweet corn, which is mechanically harvested, and pumpkins. Join us for a tour and a chance to look at some of the equipment and irrigation engineering used at this unique farm. We will also have an update on the berry pest situation around the state. The meeting will run from 5:00 p.m. to 7:00 p.m. We anticipate that two pesticide applicator recertification credits will be awarded for the meeting. Hold the date!

Strawberry bud weevil or “clipper” activity continues to be low in late fields that still have flower trusses with closed buds. Once the primary (king) and secondary blossoms have opened, it is doubtful that clipper can cause significant economic harm to the crop. This week, only one field in Dresden was over the threshold of 1.2 or more clipped buds per two feet of row. Raspberry and blackberry growers should be scouting for clippers on these crops. Past experience has shown that when clipper emerge late, as they have this year, they tend to be more prolific on brambles, although they do not appear to cause as much significant injury to these crops.

First Instar Tarnished Plant Bug Nymph

First Instar Tarnished Plant Bug Nymph, photo by David Handley

Tarnished plant bug activity has been spotty and mostly low in fields scouted this week. We have started finding very small nymphs in flower clusters, indicating that more may be showing up soon. These nymphs are very small (2 mm) and active, and will drop off the blossoms when disturbed. It is important to scout for them regularly, as they can appear very quickly. We tap 30 flower clusters in each field over a white plate and look for any nymphs that have fallen onto it. The threshold is 4 or more flower clusters infested with nymphs per 30 sampled. Insecticide options for tarnished plant bug include malathion, Assail®, Brigade®, Bifenture®, Dibrom®, Danitol®, and PyGanic®.

White grubs are the larvae of scarab beetles, including Japanese beetles, Asiatic garden beetles and European chafers. Similar to the root weevils, these grubs feed on the roots of strawberry plants, but 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.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Two-spotted spider mite populations appear to be building in many fields this week. This is to be expected under warm, dry weather conditions. Fields in Limington, Bowdoinham and New Gloucester had mite numbers over the recommended spray threshold, and most fields had at least some mites present. 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®, and Danitol®. Be sure to use enough liquid and pressure in the spray to get good coverage on the undersides of the leaves.

Slugs may be a problem in some fields this season. Moist conditions and mulch encourage the presence of these mollusks. Slugs usually feed at night, leaving large holes in the leaves and tunnels in the 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.

Deer:  Feeding damage by deer has been observed in several fields this spring.  Rows of plants look weak or dead and have few, if any leaves, although the root system may look healthy. When deer feed on plants during the winter the plants often die, as they are exposed and the crowns are damaged. By the time the mulch is removed, the plants just look dead, and any evidence left by the deer has washed away. Deer will also feed in the spring, eating leaves and sometimes damaging crowns. If deer are a problem in your area, it is best to fence the planting before they start feeding in it.  Temporary electric fencing is usually adequate if set up correctly in a timely manner.

Diseases:  It is still important to protect the flowers and developing fruit against infection by spores of the gray mold fungus, Botrytis cinerea. Late blooming varieties are still at a susceptible stage for infection, and varieties now beyond bloom may need additional protection if we experience significant periods of cool, damp weather.

Leather rot (Phytopthora cactorum) can be a problem in fields that experience heavy downpours of rain anytime during the bloom and fruit development period. Spores are splashed up by the rain and infect flowers and fruit, causing them to develop off colors and bad flavor. Sunken black lesions on the fruit may also be visible. Applying straw mulch between the rows to prevent berries from touching the soil and reducing soil splashing onto the berries can reduce infections. Additionally, foliar sprays of Aliette®, Prophyt® or Phostrol® applied during bloom and fruit development can prevent leather rot when there has been excess moisture in a field, especially those with a history of this problem.

Powdery mildew:  We haven’t seen symptoms of powdery mildew on foliage yet, but it may become a problem with continued warm, 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.

Leaf spot has been showing up in a few late, susceptible varieties. Look for small purple spots with white centers on the leaves. The symptoms are often first visible on the older, lower leaves but then spread throughout the foliage. Spots or lesions may also appear on the leaf and flower stems. Severe infections can weaken plants, reducing fruit size, yield, and winter survival. 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. 2 – May 25, 2018

Friday, May 25th, 2018

StrawberriesStrawberry IPM Newsletter No. 2 – May 25, 2018
Click on photos to enlarge.

FULL BLOOM IN SOUTHERN FIELDS

Time to Protect Blossoms from Gray Mold Infection

Berry Growers Twilight Meeting
Wednesday, June 6, 2018 at 5:00 p.m.
Pineland Farm in New Gloucester, Maine

Situation:
Very variable weather predominates, with mixed temperatures and cloudy days, but little rainfall in most areas. Many fields experienced one or two frost events last weekend, but growers were ready and had irrigation or row covers for protection. Early fields in southern Maine are well into bloom, with flower buds just opening 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. Once more than one inch of rain has fallen, or there has been significant shoot or flower growth that is unprotected since the last application, another fungicide application should be applied to assure adequate protection. Remember to alternate fungicide and insecticide chemical families to prevent the development of pest resistance.

Twilight Meeting Wednesday June 6th will be held at Pineland Farm, 752 Mayall Road, New Gloucester, Maine 04260. Justin Gray, Manager of Pineland Farms Produce Division will discuss berry and vegetable production on this intervale site with sandy soils and extensive irrigation engineering. The farm markets both locally thorough U-pick and a farm market, and supplies large market chains through much of the season, specializing in berries, sweet corn and pumpkins. 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 5:00 p.m. to 7:00 p.m. We anticipate that two pesticide applicator recertification credits will be awarded for the meeting. Hold the date!

Strawberry bud weevil or “clipper” activity has been low in most fields that 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 that indicate clipper feeding activity in some fields, especially along the border rows, but they are just starting to lay eggs and clip buds. Expect clipper damage to increase as temperatures warm and late blooming varieties come into bloom. Insecticide options for clipper include Lorsban®, Brigade®, Bifenture®, Danitol®, Sevin® and PyGanic®. 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.

Clipper Beetle on Strawberry Blossom

Clipper Beetle on Strawberry Blossom, photo by David Handley

Tarnished Plant Bug

Tarnished Plant Bug, photo by Charles Armstrong

Tarnished plant bug activity has been low so far, this season. We have adult bugs in most fields, but so far only a few, early instar nymphs. 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 have been found in most of the fields we scouted this week, but mostly in fairly low numbers. Only one field exceeded the recommended spray threshold. Mites typically proliferate under hot, dry conditions like we had last fall, so fields may have harbored a high mite population. Once temperatures become warmer we may see more problems with mites. 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®, and Danitol®. 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 some light symptoms of cyclamen mite injury this week, but haven’t found any live mites yet. Heavily 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.

Strawberry Rootworm Beetle

Strawberry Rootworm Beetle, photo by James Dill

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.

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 haven’t yet seen early symptoms of this fungus disease in fields. However, it could become 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®, and Torino® are registered to control powdery mildew.

Leaf Spot

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 haven’t seen much 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.