Strawberry IPM Newsletter No. 6 – June 14, 2013

For full page print version, please see link at the bottom. Click on photos to enlarge.

STRAWBERRY HARVEST STARTS SLOW, BUT PROMISING

Wet, Cool Weather Slows Ripening, Elevates Fruit Rot Threat

Situation: Another cool, wet stretch of weather has slowed strawberry ripening this week. Southern growers are hoping to open for general picking this weekend, but may have to wait until next weekend in some fields, although many are now spot picking fruit for farm stands and farmers markets. The crop looks very good in most fields, despite the recent weather and early indications of winter injury and some frost damage.

Gray Mold on Strawberries, photo by James Dill

Diseases:  Another round of rain this week has kept the potential for gray mold infections very high. For fields that are still in the early post-bloom stage it is important to keep young fruit protected with fungicides under wet conditions. If the last application was made prior to more than one inch of rainfall, an additional fungicide spray should be considered.

Anthracnose fruit rot has been reported in fields in Massachusetts, and will likely threaten fields in Maine as well, due to the recent rains and warmer temperatures. We recommend use of fungicide products that offer control of both gray mold and anthracnose, such as Pristine® or Cabrio®, as we approach harvest time.

Third Instar Tarnished Plant Bug Nymph, photo by David Handley

Tarnished plant bugs will continue to be a problem on later ripening fruit, although development of the nymphs appears to have been hindered by the recent weather. Continue scouting in late ripening fields that still have blossoms or small green fruit for plant bug nymphs and apply a recommended insecticide if the control threshold is exceeded. Pay close attention to pre-harvest intervals of pesticide products as fields begin to ripen. Products registered for control of tarnished plant bug include Assail®, Thionex®, Malathion®, Brigade®, Danitol® and PyGanic®.

Spittlebug, Photo by David Handley

Spittlebug masses have been noticed in some fields this week. The spittle masses are usually found on the leaf stems just below the leaflets, and annoy pickers who get the spittle on their hands and arms during harvest. Spittlebugs tend to be a greater problem in weedy fields. Pesticides currently registered for spittlebug control include Provado®, Thionex®, Danitol® and Brigade®.

Spotted wing drosophila (Drosophila suzukii) is a new pest, introduced into Maine in 2011, which appears to have become established here. This insect may be a concern for late ripening strawberries, and will certainly pose a serious threat to day-neutral strawberries, fall raspberries and blueberries. This is a small “vinegar fly”, similar to those that hover around over ripe fruit in your kitchen. However, this species will lay its eggs on fruit before it ripens, so the fruit will be contaminated with small white maggots just as it is ready to pick. Infested fruit quickly rots and has no shelf life. This species can complete a generation in less than two weeks, with each female laying hundreds of eggs, so millions of flies can be present soon after just a few enter a field.  This makes them very difficult to control, and frequently repeated insecticide sprays (3 to 5 times per week) may be needed to prevent infestations once the insect is present. While the spotted winged drosophila can overwinter in Maine, it may not build up to damaging levels until late in the summer. This could mean that June bearing strawberries will not be threatened, but later ripening fruit such as day-neutral strawberries, raspberries and blueberries will need to be protected.

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

A single spotted wing drosophila was caught in a trap in Massachusetts this week. This is not cause for alarm (it’s actually later than the first capture last year), and no controls are being recommended at this time. But it does suggest that this insect will be growing more active in the coming weeks and that populations will start building thereafter. We will be setting out monitoring traps for spotted winged drosophila in fruit plantings around Maine over the next few weeks to gather as much information on it as we can, and determine how much of a threat this pest will pose this season. For more information on this new and important pest, visit Michigan State University’s Spotted Wing Drosophila website. There is a good fact sheet series on this pest available for free download on the Penn State website.

Review:  Keeping Strawberries Fresh for Market
If you‘re bringing fruit to market, make sure that it arrives in the best condition possible. Strawberries cool most efficiently if harvested early in the morning before they build up any field heat. Place fruit into refrigerated storage quickly and keep it out of direct sunlight. Fruit should be stored at 32°F and 95% relative humidity. Cold air should be moved through the boxes or flats of fruit with a circulating fan and/or exhaust fan to cool most efficiently. Temperatures lower than 32°F may freeze the fruit and ruin its fresh quality. A small, well-insulated building cooled with air conditioners and fans can provide effective temporary storage for strawberries. If you don’t have refrigeration facilities, keep the fruit as cool as possible by harvesting when air temperatures are cool, and keeping it out of direct sunlight. Transport the fruit to market as quickly as possible, and harvest only what you think you can sell in a day.

Annual Pre-Harvest Checklist for Pick-Your-Own
It’s that time again! As harvest approaches, we like to remind you to take a moment and make sure that your farm is prepared to give your customers an enjoyable experience. Take our annual review below to evaluate your customer readiness. 

√      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:  Highmoor Farm Fruit and Vegetable Growers Field Day July 31, 2013
For more information visit the Highmoor Farm webpage.

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

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.

Wednesday, July 31, 2013
9:00 AM to 3:00 PM
Highmoor Farm, 52 US Route 202, Monmouth, Maine
Registration fee is $20.00.  Preregistration is strongly encouraged.

1 Pesticide Applicator recertification credit for the morning program and
1 Pesticide Applicator recertification credit for the afternoon tour

The Maine State Pomological Society and Maine Vegetable and Small Fruit Growers Association will be joining with the Maine Agricultural and Forest Experiment Station and the University of Maine Cooperative Extension to hold a public field day at Highmoor Farm in Monmouth on Wednesday, July 31, 2013, rain or shine.

Highmoor Farm is the Field Research Station for fruits and vegetables, and has been working with Maine farmers to improve crop production since 1909, when the farm was purchased by the state to carry out research on orchard practices. For more than 100 years, researchers at Highmoor Farm have helped to develop cultural techniques, new varieties and pest management practices to improve the success of Maine’s vegetable and fruit farmers.

This year’s field day will include tours of current research projects in tree fruit, including new apple varieties with scab resistance, and projects in vegetables and berries, including grape and raspberry variety trials, sweet corn evaluations, pumpkin trials, broccoli evaluations, as well as high tunnel tomatoes, irrigation and compost application in high tunnels, trellis installation and ORSI picking platforms.

Participants may receive one Pesticide Applicator recertification credit for attending the morning program, and one Pesticide Applicator recertification credit for attending the tree fruit tour or the berry and vegetable tour. Growers are welcome to attend the whole day, or may come for just the morning or afternoon programs and tours. Whichever you decide, please plan to be there for lunch to share some time and informal discussion with fellow farmers, research and Extension staff and state officials. Please contact Pam St. Peter at pamela.stpeter@maine.edu or 207.933.2100 to preregister. Cost for registration (including lunch) is $20.00 per person and checks are to be made payable to University of Maine Cooperative Extension.

AGENDA

Directions to Highmoor Farm, 52 US Route 202, Monmouth, Maine 04259 (207.933.2100)

Traveling North on I-95:  Drive north on the Maine Turnpike (I-95) and take Exit 86 in Sabattus. Turn left onto Route 9/Middle Road. Travel about 2 miles on Route 9 East, then turn left onto Route 132. After 4.5 miles, turn left onto Leeds Junction Road. Travel about 2.8 miles, then turn right onto U.S. Route 202 and travel about 1.3 miles up the road until you see Highmoor Farm on the right.

Traveling South on I-95:  Take Exit 109B in Augusta. Continue west on U.S. Route 202 and travel about 15 miles. Highmoor Farm will be on the left.

If you are a person with a disability and will need any accommodations to participate in this program, please call Pam St. Peter at the Highmoor Farm at 207.933.2100 or TDD 1.800.287.8957 to discuss your needs at least 7 days prior to this event.

Strawberry IPM Newsletter No. 5 – June 7, 2013

For full page print version, please see link at the bottom. Click on photos to enlarge.

Diseases:  The risk of gray mold infection remains very high, with significant rainfall predicted over the next few days. It is important to keep blossoms and fruit protected with fungicides under wet conditions. If the last application occurred over a week ago, or more than one inch of rain has fallen since the last application, an additional fungicide spray should be considered.

Anthracnose fruit rot also remains a threat as tropical storms often create the wet fields and high temperatures that are conducive to the development of this fruit rot. 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. Aliette®, Agri-Phos® or Phostrol® applied during fruit development can help prevent leather rot when the risk of this disease is high.

Powdery mildew is just starting to appear in some fields this week. This was encouraged by recent warmer weather. Leaves that are cupping upward are the most notable symptom for this fungus disease, and you may also see red streaking on leaf and flower stems. We anticipate that powdery mildew will become more prevalent soon, because it prefers warm, humid conditions. Fungicides for gray mold that also offer control of powdery mildew include Topsin-M® and Pristine®.

Leaf Spot, photo by David Handley

Leaf spot/leaf blight infections were noticed in most fields we scouted this week. Leaf spot or leaf blight, caused by the fungus Phomopsis obscurans, was the most common problem. This disease usually appears on mature leaves as small purple or red spots with white or brown centers. Over time the spots may coalesce into a larger lesion, and give the leaf a burned appearance. The disease can spread onto the fruit stems and calyxes, giving them an unattractive reddish-brown discoloration. Leaf scorch is caused by a different fungus, and has been less common this spring. The spots are smaller and don’t have the white or brown centers. The spots often coalesce to turn the leaves purple and necrotic. 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®, Rally® and Pristine®.

First Instar Tarnished Plant Bug Nymph, Photo by David Handley

Tarnished plant bug populations were significantly higher in many fields this week. Half of the fields we scouted were over the control threshold for plant bug nymphs and sprays were recommended. At this time we are finding mostly very small, green, first and second instar nymphs. They can be distinguished from similarly colored aphids because they are much more active, and will run rapidly when disturbed. The nymphs and adults are feeding on flowers and developing fruit and will cause the berries to have hard, seedy ends and other malformations. Products registered for control of tarnished plant bug include Assail®, Thionex®, Malathion®, Brigade®, Danitol® and PyGanic®.

Clipper on Strawberry, photo by David Handley

Strawberry bud weevil or “clipper” injury has been noted in several fields this week and we found more live clippers than in any previous scouting trips this year. However, most of the injury was to lower order (late, small) flower buds, so the economic significance of the potential fruit loss is minimal, and no sprays were recommended. 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.

Two-spotted spider mites were found in most locations this week but, with the exception of one field, were well below the control threshold. The predicted wet weather will probably slow further spider mite development, at least temporarily; but we still anticipate that populations will rise when hotter, drier weather arrives.

Sap beetles have been found in two fields this week while scouting for tarnished plant bug. This is not cause for alarm yet, but growers should be aware that they are present and 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 seen in the holes they’ve chewed into ripe fruit, 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, specifically cedar waxwings, will soon be moving into fields to feed on ripening fruit. Waxwings often destroy many of the early ripening fruit, despite our best efforts to scare them off. Only by keeping a near constant presence in the field and eliminating roosting sites can you reduce the damage. Feeding is reduced once the fields start to be regularly harvested and customers are present.

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. The permit is good for one year, so if you have problems this season, consider applying for a permit this winter, to give you the option to kill birds, if necessary, next season. The Wildlife Damage Office has recommendations for managing birds in crops, and some control options available through their office. For more information call the office in Augusta at 207.629.5181. The office is located in the Capital West Business Center at 79 Leighton Road in Augusta.

Hold the date:  Highmoor Farm Fruit and Vegetable Growers Field Day July 31, 2013.

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

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. 4 – May 31, 2013

For full page print version, please see link at the bottom. Click on photos to enlarge.

WARMER TEMPS SPEED STRAWBERRY DEVELOPMENT

Higher Temps also Likely to Increase Insect and Mite Activity

Situation: Damp weather stretched through most of the week again, but now things are heating up fast, and the sudden change of temperature should hasten fruit ripening. High temperatures may also stress plants, especially those that experienced winter injury, grub feeding, or any other factor that compromised the plants’ ability to take up water. If plants appear to be wilting, dull colored or otherwise stressed, it may be necessary to irrigate if soils have become dry, to help stressed plants prosper through the high temperatures. Early varieties in southern Maine are now beyond full bloom, and are showing green fruit. Later varieties are mostly in bloom, and the bees have been active under the better weather conditions. Fields that were under row covers are starting to show a few ripe fruit and more will be ripening fast over the next few days. Insect activity remains pretty low for the time being, although we are starting to see an increase, which will be enhanced by the higher temperatures.

Gray Mold on Strawberries, photo by James Dill

Diseases:  The prolonged damp conditions earlier in the week have kept the risk of gray mold infection very high. So, if it has been more than a week since the last fungicide application, or the field has received more than one inch of rain since the last application, it would be best to apply another fungicide spray.

Anthracnose fruit rot is favored by warm temperatures and wet field conditions, a combination many fields will see over the next few days; so consider using a fungicide that will offer control of both gray mold and anthracnose when making your next fungicide application, such as Pristine® or Cabrio®.

Leather rot (Phytopthora cactorum) may also be an issue in fields where standing water has been prevalent this spring. A spray of Aliette®, Agri-Phos® or Phostrol® applied during bloom and fruit development can help prevent leather rot where the risk of this disease is high.

Powdery mildew:  We have not yet seen any significant signs of powdery mildew, but we anticipate it may become more evident soon, because this fungus can proliferate rapidly under warm, humid conditions. Some fungicides sprays for gray mold can also offer good control of powdery mildew, including Topsin-M® and Pristine®

Slime mold:  I have had a report of slime mold from our friends in New Hampshire this week. Slime mold fungi can occur on strawberry plants and mulch when we get very wet, warm weather in the spring or fall. The mold appears as a creamy white or tan colored, jellylike mass growing out of the soil and up onto leaves and flower clusters or just on top of the mulch. The mass is amorphous and may have gray or black fruiting structures covering its surface. The mold dries out to a hard, crusty structure with powdery spores. Slime mold fungi are not parasitic to plants; they just climb them to improve the spread of their spores, but the masses can smother single leaves or fruits and be unsightly. Slime molds disappear when dry weather returns. They do not require any management.

Clipped Flower Buds from Strawberry Clipper, photo by David Handley

Strawberry bud weevil or “clipper” is becoming more active as temperatures rise. However, some early blooming varieties have already developed beyond the point where clipper can do significant harm. Most fields had only very light clipper injury in later flowering varieties this week; none of the fields were over the action threshold. Late blooming fields should still be scouted for clipped buds.

Tarnished plant bugs remain fairly scarce this week. We have seen a few adults and some small nymphs in the fields we scouted, but none were over the action threshold. Expect activity to increase as things get drier and warmer.

Strawberry Mite Symptoms, photo by David Handley

Two-spotted spider mites were found in higher numbers this week, and distributed over a larger area, but all fields were below the action threshold. The extended cool, wet weather likely slowed spider mite development, but we should anticipate that populations will rise under the recent hotter, drier weather.

Spittlebug, photo by David Handley

Spittlebugs:  Be on the lookout for spittlebug masses in your fields as we approach harvest time. Although we haven’t noted any in fields this week, they may start to appear soon. The frothy spittle masses are found on the leaf stems (petioles), just below the leaflets, usually showing up around bloom. Although spittlebugs don’t pose a significant threat to the plants, the frothy spittle masses create an annoyance for pickers. Spittlebugs overwinter as eggs and the nymphs emerge in late May. The spittle masses may be at the base of the plants, so spread the leaves and inspect the crowns, leaf bases, leaf stems, and flower stems looking for them. The small, yellow-orange nymphs will be under the spittle. If the average number of spittle masses is more than two per square foot, a treatment may be warranted. Spittlebugs tend to be a greater problem in weedy fields. Pesticides currently registered for spittlebug control include Provado®, Thionex®, Danitol® and Brigade®.

Slug on Strawberry, photo by James Dill

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.

Highmoor Farm Fruit and Vegetable Growers Field Day July 31, 2013
Plans are well underway for the Highmoor Farm Field Day to be held on Wednesday, July 31. Growers will have an opportunity to tour the fruit and vegetable research plots at the farm, part of the Maine Agricultural and Forest Experiment Station, and hear Extension specialists and guest speakers discuss current research on apples and grapes. University of Maine leaders and state legislators will also be on hand to offer updates on programs and legislation effecting farming in Maine. Please join us for the program, farm tours and lunch. More information will be coming soon.

Sincerely,

David T. Handley
Vegetable & 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

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 – May 24, 2013

Wet Strawberry Field, photo by David Handley

Diseases:  Bloom is the critical time to protect strawberries from developing gray mold caused by the Botrytis cinerea. The rain of the past few days has made conditions very conducive to fungal sporulation and flower infection. Two to three sprays of fungicide during bloom are often required to protect against gray mold. Fungicide choices for control of gray mold in strawberries include captan/Topsin M® tank mix, Elevate®, Captevate® (a pre-mix of captan and Elevate®), Switch®, Scala® and Pristine®.

Leather rot (Phytopthora cactorum) can be a problem when there is water standing in the fields during bloom and fruit development, especially if the fields were not mulched last fall and the plants are on bare, wet soil. Leather rot should be managed by growing strawberries in well-drained soil and applying straw mulch between the rows to prevent berries from touching the soil and to reduce soil splashing up onto the berries. Foliar sprays of Aliette®, Agri-Phos® or Phostrol® can be applied during bloom and fruit development to prevent leather rot when there is excessive moisture in the field, especially in fields with a history of this problem.

Anthracnose on Strawberry, photo by North Carolina State University

Anthracnose fruit rot is a potential problem when fruit ripens in fields that are wet from irrigation or rain. This fungus disease is favored by warm, humid conditions and can spread rapidly during rains or when fields are irrigated with overhead sprinklers. In cool seasons, it may appear close to harvest or may not show up at all. Anthracnose fruit rot is identified by black sunken lesions with wet, orange (and sometimes gray) spore masses in them. The fungus can survive and multiply on leaves without visible symptoms, appearing suddenly as a fruit rot when the conditions are right. Fungicides such as Cabrio® and Abound® can provide good control of anthracnose.

Powdery Mildew, photo by David Handley

Powdery mildew:  No severe symptoms of powdery mildew have been observed yet, but we’re starting to see some leaf cupping in fields, suggesting that this disease may become a problem when temperatures start to rise. Upward cupping of the leaves and reddish streaking or lesions on the leaf and flower stems are the most obvious symptoms of powdery mildew. White, powdery growth on the undersides of the leaves appears as the disease develops further.

Strawberry bud weevil or “clipper” is becoming active as flower buds emerge. I have found one field with clipper at levels over threshold this week, but most fields were showing very little, if any damage. Early blooming varieties may have developed beyond the point where clipper can do significant harm to buds, but later blooming fields should still be scouted for injury. Clipper is likely to become more active when conditions become a little drier and warmer.   

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

Tarnished plant bugs adults are few and far between this week, which is typical in this kind of weather, but I still have not found any nymphs in blooming fields. It is difficult to find nymphs on wet plants, so we may see activity increase considerably when things dry out. But for now, no fields have been over threshold.  

Cyclamen mites:  We continue to see symptoms of cyclamen mite in strawberry fields this week, including weak growth, crinkled leaves and yellow, pinkish or blackened discoloration. Sprays for these mites must be applied with lots of water to carry the material down into the crowns where the mites reside. Portal®, Thionex® and Kelthane® are registered for control.  

Cyclamen Mite Damage, photo by David Handley

Two-spotted spider mites were not found over threshold in any fields this week. Cool, wet weather tends to significantly slow spider mite development in strawberry fields, but expect populations to rise as conditions become warmer and drier, and keep scouting.   

White grubs:  We have found white grubs in three different fields this week, most likely the larvae of Asiatic garden beetle or European chafer. These grubs have legs and a dark, swollen rear end. They are found in the soil around the roots of weak plants.   Admire Pro®  can be used to control white grubs and should be applied within two hours of irrigation or rainfall to get the chemical into the root zone. This product has a 14 day pre-harvest interval.  

Spring fertilizer for strawberries
Heavy nitrogen fertilizer applications are not recommended in the springtime because excess vegetative growth at this time will result in a dense leaf canopy that will cover flowers and fruit, and encourage gray mold and two spotted spider mites. In the matted row system, most of the nitrogen fertilizer should be applied following harvest to stimulate new leaf and runner growth. For established beds, only 10-20 pounds of actual nitrogen should be applied in the spring. Calcium nitrate [Ca(NO₃)₂, 15% N] is a recommended source of nitrogen at this time because it is readily available, not volatile, and also provides calcium, which can help with fruit development.  Boron is another nutrient which can help early spring growth, and is especially important in the pollination and fertilization process that helps determine fruit size and quality. However, excessive amounts of boron can be toxic to strawberry plants, so only one to two pounds of actual boron (B) is recommended per acre during the spring. This is often applied as a foliar spray in a material such as Solubor® (20% B). While foliar sprays are often an inefficient way to get nutrients to the plants, they are helpful when trying to evenly distribute a small amount of material over a large area.

Honey bee on flower

What about pollination?
After a hard winter for bees and lots of rain during bloom, growers are concerned about good pollination in their strawberries. Cultivated strawberry flowers are self-fertile, meaning that they don’t require cross-pollination with other varieties like some other fruit crops, such as apples or blueberries. Some studies have shown that strawberries will produce a good crop in the absence of bees, with pollination being carried out by wind and small, native insects. Other studies have shown an increased fruit quality and size when bees help with pollination, so it is certainly good to have them working in the strawberry fields, but perhaps not essential for this particular crop.

2013-2014 New England Small Fruit Management Guides are available from the University of Maine Cooperative Extension at Highmoor Farm. This new, updated edition of the guide contains the latest information on management options for small fruit pests as well as cultural information. Cost of the guide is $10.00 plus $2.53 postage for a total of $12.53. To order a guide, please send your check made payable to UMaine Cooperative Extension mailed to: Highmoor Farm, P.O. Box 179, Monmouth, Maine 04259, atten. Pam St. Peter. For more information, contact Pam St. Peter at 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 Ave
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 17, 2013

For full page print version, please see link at the bottom. Click on photos to enlarge.

Sprayer Calibration Clinic on May 21, 2013 at 2:00 p.m.
Twilight Meeting on May 21, 2013 at 5:00 p.m.
Pikes Farm to You in Farmington, Maine

STRAWBERRY BLOOM UNDERWAY

Few Insect or Disease Problems, Winter Injury Widespread

Frost Injury to Flowers and Leaves, Photo By David Handley

Situation: A little rain last weekend provided some relief from this very dry spring for most fields.  Frost hit many fields over two to three nights early in the week, and some injury has been noted wherever irrigation wasn’t able to protect the blossoms.   Plants in southern Maine are now showing open primary (king) blossoms on early varieties, while in later varieties buds are still emerging from the crown.  Fields that were under row covers are in full bloom, or just beyond, suggesting that we could see some ripe fruit in just a couple of weeks, weather permitting.  I am still finding winter injury, especially in older fields, where straw and or snow cover was inadequate during the coldest part of the winter.  On the bright side, insect activity remains fairly low in all fields scouted this week, but it is important to keep scouting during the bud emergence through bloom stages, because this is when the plants are most susceptible to clipper and tarnished plant bug.  Bloom is also the most critical stage for preventing infestation by Botrytis spores, which cause gray mold.

Sprayer Calibration Clinic and Twilight Meeting
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a sprayer calibration clinic for airblast sprayers at David Pike’s Farm to You in Farmington on Tuesday, May 21 at 2:00 p.m. George Hamilton with the University of New Hampshire Cooperative Extension will demonstrate new tools for making sure your sprayer is delivering the correct rate of pesticides to your crops. Having a sprayer properly calibrated will improve the effectiveness of your sprays, and can save you money by reducing the amount of pesticide used and reducing crop losses due to pests. Participants will receive two pesticide applicator recertification credits. The calibration clinic will be followed at 5:00 p.m. by a tour of David Pike’s strawberry and vegetable fields. David has been a leader in innovative strawberry production techniques, including raised beds, plastic mulch, fertigation, fall cropping, and season extension. There will be some new low tunnel technology on display, as well as replant experiments and new varieties on trial. One pesticide applicator recertification will be awarded for the meeting. The location is 115 Mount View Road. (corner of Routes 2 & 4 and the Whittier Road) in Farmington, ME 04938. There will be signs posted. The farm phone number is 207.778.2187. Cost for the clinic is free and no registration is required. Hold the date!

Drip Irrigation Workshop
Wednesday, May 22, 2013, 3:00 p.m. to 6:00 p.m. at the Sherman Farm, 2679 East Conway Road, Center Conway, NH 03813. The farm phone number is 603.939.2412.

The purpose of this meeting is to review what drip irrigation options and strategies vegetable and fruit growers should be considering for the coming growing season.  Trevor Hardy, of Brookdale Fruit Farm and George Hamilton, UNH Cooperative Extension will present a hands-on demonstration on setting up a drip irrigation system and describe the various components of a system, including set ups for high tunnels.  Toro Irrigation Representative Bill Wolfram will also be present.  The meeting will begin at 3:00 p.m. and will run until around 6:00 p.m.

For more information contact:

Olivia Saunders, UNH Extension Field Specialist
603.447.3834, e-mail: olivia.saunders@unh.edu, OR

George Hamilton, UNH Extension Field Specialist,
603.641.6060, email: george.hamilton@unh.edu.

2013-2014 New England Small Fruit Management Guides are now available at Highmoor Farm. This new, updated edition of the guide contains the latest information on management options for small fruit pests as well as cultural information. Cost of the guide is $10.00 plus $2.53 postage for a total of $12.53. To order a guide, 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 933.2100 or pamela.stpeter@maine.edu.

Clipper Injury, Photo by David Handley

Strawberry bud weevil or “clipper” should now be coming active as flower buds emerge. We have not found clipper at levels over threshold in any fields scouted to date, but it is important to keep a sharp lookout for clipped buds now, especially along wooded borders of the field.  If the average number of clipped buds exceeds 1.2 per two feet of row, or if live clippers are being found, control measures are recommended.

First Instar Tarnished Plant Bug Nymph, photo by David Handley

Tarnished plant bug adults are being reported in apple orchards in southern Maine, but we have not yet found any nymphs in the strawberry fields we have scouted. Strawberries are preferred hosts at this time of year, so we should expect to start seeing both adults and nymphs soon. 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 blossoms start to open.

Cyclamen mites:  We have found symptoms of cyclamen mites in several plantings this spring. Symptoms include weak growth, crinkled leaves and yellow, pinkish or blackened discoloration. Cyclamen mites are too small to be seen without magnification and reside in the crown of the strawberry plant feeding on the developing leaves and flower buds. Miticides must be applied in lots of water to be sure that the material is carried down into the crowns where the mites reside.

Two-spotted Spider Mites, Photo by David Handley

Two-spotted spider mites have been found exceeding the management threshold at one southern location this week, in a field that was under row covers. This is often where we first find mite problems. Expect mite problems to increase as the temperature increases, especially under dry conditions.

White grubs:  We have had several reports of white grub infestations in fields this spring. Weak plant growth may be the result of grubs feeding on roots. These grubs are the larvae of beetles, including European chafer and Asiatic garden beetle. The grubs have legs and a swollen anterior (rear end). The grubs can be found by pulling up weak plants and sifting through the soil that surrounded the roots.   Controlling white grubs when they are established in a field is difficult. Admire Pro® is labeled for control of white grubs and should be applied within two hours of irrigation or rainfall to get the chemical into the root zone. There is still time to apply nematodes to control the grubs. (Optimal timing is about mid-May.) Two species of nematodes appear to offer the best control. Heterorhabditis bacteriophora (Hb) is the best candidate when the soil temperature is above 60 degrees (‘J-3 Max Hb’ from The Green Spot Ltd., ‘GrubStake Hb’ from the Integrated Biocontrol Network, ‘Larvanem’ from Koppert Biological Systems.

Diseases:  Just a reminder that bloom is the critical time to protect strawberries from developing gray mold caused by the fungus Botrytis cinerea. Two to three sprays of fungicide during bloom are typically required to provide good protection against this disease. Any moisture, including irrigation, fog, or even pesticide sprays can stimulate Botrytis spores to germinate.  Fruit infections take place almost exclusively through the flowers, so gray mold control efforts must be focused on the bloom period.

Sincerely,

David T. Handley
Vegetable & 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

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.

Any person with a disability who needs accommodations for these programs should contact Pam St. Peter at 207.933.2100 or TDD 1.800.287.8957 to discuss their needs at least 7 days in advance.

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 calibration clinic will be followed at 5:00 p.m. by a tour of David Pike’s strawberry and vegetable fields.  David has been a leader in innovative strawberry production techniques, including raised beds, plastic mulch, fertigation, fall cropping, and season extension.  There will be some new low tunnel technology on display, as well as replant experiments and new varieties on trial.  One pesticide applicator recertification credit will be awarded for the meeting.

Pike’s Farm to You is located at 115 Mount View Road (near the corner of Routes 2 & 4 and the Whittier Road) in Farmington, Maine 04938.  There will be signs posted.  The farm phone number is 207.778.2187.  Cost for the clinic is free and no registration is required.  For more information, please contact David Handley at 207.933.2100 or david.handley@maine.edu.

Any person with a disability who needs accommodations for this program should contact Pam St. Peter at 207.933.2100 or TDD 1.800.287.8957 to discuss their needs at least 7 days in advance.

Strawberry IPM Newsletter No. 1 – May 9, 2013

For full page print version, please see link at the bottom. Click on photos to enlarge.

Sprayer Calibration Clinic on May 21, 2013 at 2:00 p.m.
Twilight Meeting on May 21, 2013 at 5:00 p.m.
Pikes Farm to You in Farmington, Maine

2013 STRAWBERRY PEST MANAGEMENT SEASON BEGINS

Winter Injury Worries

Situation: What seemed to start as a relatively normal spring has now become a very dry spring indeed, with most areas in New England significantly behind on rainfall. While this has helped growers to get on to fields early to plant, established plantings of strawberries could be suffering from drought stress.  Dry conditions can also reduce nutrient uptake, resulting in deficiencies, most notably calcium. In southern locations, flower buds are now emerging from crowns in plantings that were mulched over the winter. Plantings that were not mulched are a little further advanced, and plantings that were under row covers are coming into bloom. Frost protection becomes a priority now, and irrigation should be set up to provide frost protection for buds and flowers on any night when temperatures drop below freezing.  Bear in mind that fields that are irrigated for frost repeatedly during bloom face an increased risk of bacterial angular leaf spot.

Frost Injury, photo by David Handley

Winter injury is common in fields this spring, especially in plantings that either were not mulched or mulched late in the winter due to trouble getting onto the fields in the fall. Frost heaving is also apparent in fields with heavier soils, which injures plant roots and inhibits water and nutrient uptake.  Injured plants appear weakened, with small, dull colored leaves, and crowns that may be pushed out of the soil. Cutting into the crowns will reveal dark brown discoloration in the internal tissue. Helping plantings recover from winter injury involves compensating for the damaged vascular system.  Make sure the plants get plenty of water, especially in this dry period, and it may help to apply extra nutrients to encourage root growth and recovery, including nitrogen, calcium, and phosphorus. While we do not recommend heavy nitrogen fertilizer applications in the spring, up to 20 pounds of actual N (e.g. 125 lb. calcium nitrate) may improve early spring growth.

Sprayer Calibration Clinic & Twilight Meeting
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a sprayer calibration clinic for airblast sprayers at David Pike’s Farm to You in Farmington on Tuesday, May 21 at 2:00 p.m. George Hamilton with the University of New Hampshire Cooperative Extension will demonstrate new tools for making sure your sprayer is delivering the correct rate of pesticides to your crops. Having a sprayer properly calibrated will improve the effectiveness of your sprays, and can save you money by reducing the amount of pesticide used and reducing crop losses due to pests. Participants will receive two pesticide applicator re-certification credits.

The calibration clinic will be followed at 5:00 p.m. by a tour of David Pike’s strawberry and vegetable fields. David has been a leader in innovative strawberry production techniques, including raised beds, plastic mulch, fertigation, fall cropping, and season extension. There will be some new low tunnel technology on display, as well as replant experiments and new varieties on trial. One pesticide applicator re-certification credits will be awarded for the meeting. Hold the date! We’ll give driving directions next week.

2013-2014 New England Small Fruit Management Guides are now available at Highmoor Farm. This new, updated edition of the guide contains the latest information on management options for small fruit pests as well as cultural information. Cost of the guide is $10.00 plus $2.53 postage for a total of $12.53. Copies of the 2012-2013 New England Vegetable Management Guide with color pictures of the important pests and diseases are also available at Highmoor Farm. Cost of the guide is $25.00 plus $3.43 postage for a total of $28.43.

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 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 receive free copies of the guides. For MVSFGA membership information, contact Bill Jordan at 799.1040.

Scouting
We will start scouting strawberry fields for major insect pests in earnest next week, including volunteer farms, in North Berwick, Wells, Cape Elizabeth, Poland Spring, New Gloucester, Dresden, Monmouth, Wayne, and Farmington, and will be reporting our findings through this newsletter on a weekly basis until harvest time. You can also get quick access to this information through the Highmoor Farm blog or the Pest Management web page.  If you would prefer to receive this message via e-mail, please give us a call at 933.2100 or send an e-mail message to: pamela.stpeter@maine.edu.

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 online Publications Catalog.  You should also have a copy of the 2013-2014 New England Small Fruit Pest Management Guide, which contains the latest information on management  options for the major strawberry pests as well as scouting information.

Clipper Beetle on Strawberry Bud, photo by James Dill

Strawberry bud weevil or “clipper” will soon be active as flower buds begin to emerge. 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®.

Tarnished Plant Bug Adult, photo by David Handley

Tarnished plant bugs adults have been found in southern Maine, indicating that they 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 now!  Insecticide options for tarnished plant bug include malathion, Brigade®, Danitol®, Thionex® and PyGanic®.

Cyclamen Mite Damage, photo by David Handley

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. Miticides such as Thionex® or Kelthane® and Temprano® 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.

Two-spotted Spider Mites, photo by David Handley

Two-spotted spider mites have not yet been a problem this spring, but growers with plants under row covers should be alert. This is often where we first find mite problems. Spider mites will reproduce rapidly when warmer weather arrives, so it is important to scout for them regularly. Spider mites 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®, 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).

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 (‘J-3 Max Hb’ from The Green Spot Ltd., ‘GrubStake Hb’ from the Integrated Biocontrol Network, ‘Larvanem’ from Koppert Biological Systems).

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 can not 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, 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.

Gray Mold on Strawberries, photo by James Dill

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.

Red stele root rot
Although fall and early spring conditions were not especially conducive to red stele development, damp conditions this spring should make us 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.  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, photo by David Handley

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. 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.

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.

Sincerely,

David T. Handley
Vegetable & 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

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.

Orders are now being taken in the”Grow It Right!” plant sale for highbush blueberry plants — three young plants, two varieties per pack for $35.95 and asparagus — a pack of 10 crowns for $15.00. Plants must be ordered by April 30, 2013 and will be available for pickup at University of Maine Cooperative Extension county offices and at Highmoor Farm in Monmouth on Saturday, May 18. UMaine Extension county office locations are listed online.

UMaine Extension experts will provide advice on growing blueberries and asparagus, as well as take-home instructions from Master Gardener volunteers. Online resources are available to gardeners throughout the growing season and harvest.

“This is more than a plant sale. It is an educational experience with positive results,” says Richard Brzozowski, UMaine Extension educator in the Cumberland County office.

Money raised will assist Master Gardener Volunteer projects and provide scholarships for participants. Since its inception more than 30 years ago, the UMaine Extension Master Gardener Volunteers program has assisted in dozens of community horticultural projects across the state, including Maine Harvest for Hunger, youth gardening and other community-based volunteer efforts.

A soil test is recommended prior to planting to help gardeners get the most out of their garden site. Additional information is available at the plant sale website.

For more information about Grow It Right! contact Brzozowski at 207.781.6099 (toll-free in Maine 800.287.1471), or Marjorie Peronto at 207.667.8212 (toll-free in Maine 800.287.1479), or email richard.brzozowski@maine.edu or marjorie.peronto@maine.edu.