Posts Tagged ‘pest management’

Sweet Corn IPM Newsletter No. 5 – July 26, 2013

Friday, July 26th, 2013
Sweet Corn
Sweet Corn IPM Newsletter No. 5 – July 26, 2013
For full page print version, please see link at the bottom. Click on photos to enlarge.

CORN INSECT ACTIVITY REMAINS MODERATE

Squash Vine Borer and Spotted Wing Drosophila Pressure Increasing

SITUATION
Early corn harvest is coming into full swing in southern Maine. Maturity is variable, but overall quality looks good. The weather pattern has been limiting movement of moths into the region, so we have seen very little change in the populations of corn earworm and fall armyworm this week. A front moving in from the south this weekend may change the situation, but for now pest pressure remains moderate.

European Corn Borer on Ear of Corn

European Corn Borer on Ear, photo by David Handley

European corn borer: Moth catches in the southern parts of the state remain quite low this week. Two of the more northern sites had relatively high counts, however. Silking fields in Charleston and Palmyra were well over the threshold of 5 moths per week but the Charleston site is also on a spray schedule for corn earworm, so no additional sprays should be required. European corn borer feeding damage was over threshold in pre-tassel fields in Biddeford, Nobleboro and Warren this week.

Corn earworm:  Moths counts remain quite low in all locations this week and most locations did not require protection. A 4-day spray interval was recommended for Charleston and Garland. A 5-day spray interval was recommended for Levant. A 6-day spray interval was recommended for silking fields in Cape Elizabeth, Hollis and Farmington.

Fall armyworm:  Most sites had few or no fall armyworm moths in pheromone traps this week. The exceptions were Biddeford and New Gloucester, which both had 5 moths, exceeding the weekly threshold of three for silking corn. Neither site was under a spray interval for corn earworm so a spray was recommended for all silking corn. Single moths were caught in just three locations this week including Cape Elizabeth, Charleston and Oxford. Two moths were caught in Nobleboro. There is still relatively little fall armyworm feeding damage in younger corn fields.

Two Squash Vine Borer Moths

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

Squash vine borer moths were caught in pheromone traps in Wells, Hollis, Biddeford, Gray, New Gloucester, Nobleboro and Oxford this week. The threshold of five moths per week was exceeded in Biddeford, Hollis, Gray and New Gloucester. Be aware that this pest is very active and continues to threaten summer squash, winter squash and pumpkins. See the New England Vegetable Management Guide for control options.

Spotted Wing Drosophila Alert
Captures of spotted wing drosophila are rising this week. Flies were caught in Wells, New Gloucester, Monmouth, Dresden and Warren.  Numbers at the Warren site have increased significantly, with 84 flies caught this week. The larvae of these flies can quickly destroy any soft fruit such as raspberries and blueberries. If spotted wing drosophila has been captured in your area and you have ripening berries, the crop should be protected at this time with a recommended insecticide. Regular and repeated treatments are usually needed to keep fruit from becoming infested. Visit our Spotted Wing Drosophila blog for more details.

Highmoor Farm

FINAL REMINDER: Highmoor Farm Fruit and Vegetable Growers Field Day July 31, 2013
Join us for the Highmoor Farm Field Day and Summer Tour to be held on Wednesday, July 31, starting at 9:00 a.m. Please join us for the program, farm tours and lunch. Registration fee is $20 per person, including lunch, and preregistration is strongly encouraged. For more information, visit the Highmoor Farm website or call 207.933.2100. If you are a person with a disability and will need any accommodations to participate in this program, please call Pam St. Peter at Highmoor Farm, 207.933.2100 or TDD 1.800.287.8957 to discuss your needs at least 7 days prior to this event.

Sincerely,

David T. Handley
Vegetable & 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
Auburn 2 7 0 0% 6-day spray interval recommended on all silking corn
Biddeford 1 0 5 35% One spray recommended on silking corn for FAW
Cape Elizabeth I 0 0 1 5% No spray recommended
Cape Elizabeth II 0 0 0 No spray recommended
Charleston 3 29 1 6% 6-day spray interval recommended on all silking corn
Dayton 0 0 0 7% No spray recommended
Farmington 2 0 0 4% 6-day spray interval recommended on all silking corn
Garland 0 5 0 1% One spray recommended on silking corn for ECB
Gray 0 5 0 7% One spray recommended on silking corn for ECB
Hollis 0 0 0 7% No spray recommended
Levant 0 5 0 3% One spray recommended on silking corn for ECB
Lewiston 2 0 0 5% 6-day spray interval recommended on all silking corn
Livermore Falls 0 0 0 13% No spray recommended
New Gloucester 0 0 5  7% One spray recommended on silking corn for FAW
Nobleboro 0 1 2 23% One spray recommended ECB feeding
No. Berwick 0 0 0 3% No spray recommended
Oxford 1 2 1 6% No spray recommended
Palmyra 0 15 0 1% One spray recommended on silking corn for ECB
Sabattus 3 2 0 5% 6-day spray interval recommended on all silking corn
Wales 3 1 0 6-day spray interval recommended on all silking corn
Warren 1 1 0 15% One spray recommended for ECB feeding
Wells I 0 0 0 5% No spray recommended
Wells II 1 0 0 2% 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
http://www.umass.edu/umext/ipm/

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.

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

Sweet Corn IPM Newsletter No. 4 – July 19, 2013

Friday, July 19th, 2013

Sweet Corn

Sweet Corn IPM Newsletter No. 4 – July 19, 2013

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

INSECT ACTIVITY LOW TO MODERATE THIS WEEK

Stalled Weather Pattern Means Little Change to Pest Situation

SITUATION
Most fields did not see significant rain this week; in fact some southern and northern fields are starting to run dry. The heat has pushed corn development rapidly and a couple of early fields are just ready for harvest. Some later plantings look a bit spotty, with uneven development due to the extended cool, wet weather following planting. Generally, insect activity has been light to moderate this week, with several fields not requiring any additional protection. A predicted change in the weather pattern next week may bring about some changes in pest activity as well.

European corn borer:  Moth catches have declined to very low numbers this week, with most farms having no moths in the traps. A silking field in Charleston was the exception with 19 moths, exceeding the threshold of 5 moths per week in traps, but all of this sites are also on a spray schedule for corn earworm, so no additional sprays should be required. European corn borer feeding damage was over threshold in pre-tassel fields in North Berwick and Warren this week.

European Corn Borer Larva

European Corn Borer Larva, photo by David Handley

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Corn earworm:  Moth counts were generally low in southern Maine this week and many locations did not require protection. In the more northern sites, counts were higher, and more frequent sprays were needed on silking corn. A 4-day spray interval was recommended for Charleston and Garland. A 5-day spray interval was recommended for Levant. A 6-day spray interval was recommended for silking fields in Cape Elizabeth, Hollis and Farmington.

Fall Armyworm Moths

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

Fall armyworm:  A slight increase in fall armyworm moth activity was seen this week.  Single moths were caught in seven locations this week including Auburn, Biddeford, Farmington, Dayton, Nobleboro, Oxford and Wells. At one field in New Gloucester, five moths were caught, exceeding the three-moth threshold for the week, so a spray for all silking corn was recommended. We have found very little fall armyworm feeding damage in younger corn fields, but we expect that levels will be increasing soon.

Squash vine borer moths were caught in pheromone traps in North Berwick, Wells, Hollis, Biddeford, Gray, and New Gloucester this week. The threshold of five moths per week was exceeded in North Berwick, Hollis, Gray and New Gloucester. Be aware that this pest is now active and threatens summer squash, winter squash and pumpkins.  See the New England Vegetable Management Guide for control options.

Highmoor Farm Highmoor Farm Fruit and Vegetable Growers Field Day July 31, 2013
Please join us for the Highmoor Farm Field Day and Summer Tour to be held on Wednesday, July 31, starting at 9:00 a.m. 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, grapes and vegetables. Maine 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.

Registration fee is $20 per person, including lunch and preregistration is strongly encouraged. Visit the Field Day website for more information. If you are a person with a disability and will need any accommodations to participate in this program, please call Pam St. Peter at Highmoor Farm, 207.933.2100 or TDD 1.800.287.8957 to discuss your needs at least 7 days prior to this event.

Sincerely,

David T. Handley
Vegetable & 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
Auburn 0 0 1 6% No spray recommended
Biddeford 1 0 1 14% No spray recommended
Cape Elizabeth I 1 0 0 7% No spray recommended
Cape Elizabeth II 2 0 0 6-day spray interval recommended on all silking corn
Charleston 9 19 0 2% 4-day spray interval recommended on all silking corn
Dayton 1 0 1 4% No spray recommended
Farmington 2 0 1 1% 6-day spray interval recommended on all silking corn
Garland 11 2 0 0% 4-day spray interval recommended on all silking corn
Gray 0 1 0 3% No spray recommended
Hollis 2 0 0 6-day spray interval recommended on all silking corn
Levant 5 0 0 1% 5-day spray interval recommended on all silking corn
Lewiston 0 0 0 0% No spray recommended
New Gloucester 0 0 5 One spray recommended on silking corn for FAW
Nobleboro 0 0 1 No spray recommended
No. Berwick 0 0 0 32% One spray recommended for ECB feeding
Oxford 0 0 1 4% No spray recommended
Palmyra 0 4 0 No spray recommended
Wales 0 1 0 6% No spray recommended
Warren 1 0 0 25% One spray recommended for ECB feeding
Wells I 0 0 0 2% No spray recommended
Wells II 0 1 1 6% 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
http://www.umass.edu/umext/ipm/

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.

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

Strawberry IPM Newsletter No. 7 – July 15, 2013

Tuesday, July 16th, 2013

Strawberries

Strawberry IPM Newsletter No. 7 – July 15, 2013

RENOVATION AND WEED MANAGEMENT ISSUE

Spotted Wing Drosophila, White Grubs Threaten Berries this Summer

The winter of 2012-2013 gave us a cold, snowless start that resulted in some winter injury in exposed strawberry fields. But good snow cover later in the winter kept damage from being severe in most locations. Good growing conditions early in the spring got plants off to a quick start with a few frosts to threaten early blooming varieties. Rain during much of the bloom period raised concerns about pollination, but going into harvest the crop looked pretty good. Unfortunately, the weather just couldn’t cooperate for much of the harvest season, with heavy rain and very hot, humid conditions, especially on weekends, which kept many of the u-pick customers at home. Pickers did come out during the short intervals of decent weather and saved the harvest from being a big loss; and pre-picked sales were good, but for most farms the end result was a season that was only fair. Timely fungicide sprays through the rain provided good protection in most fields, as gray mold was kept to a minimum in spite of all the moisture. Foliar diseases, such as powdery mildew and leaf spot began to show up towards the end of the season. Insect pressure was generally light, although some fields were weakened but white grubs feeding on plant roots.

Don’t forget about your strawberries after harvest.  Follow the recommended renovation steps listed below as soon after harvest as possible; and 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.

Powdery Mildew

Powdery Mildew, photo by David Handley

Leaf Scorch

Leaf Scorch, photo by David Handley

DISEASES:  Foliar diseases should be monitored in your fields by regularly examining leaves. All of the common leaf diseases were present in fields this spring and we should expect that they will continue to be a problem through the summer. The most common summer diseases are powdery mildew, leaf spot and leaf scorch. Fungicides available for these diseases include captan, Topsin-M®, Cabrio®, Pristine® and Abound®. See the New England Small Fruit Management Guide for detailed descriptions of these diseases and their management.

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

Black Vine Weevil

Black Vine Weevil, photo by David Handley

Strawberry Root Weevil Grub

Strawberry Root Weevil Grub, photo by David Handley

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.

White Grub

White Grub, Photo by David Handley

White grubs have been a problem in some fields over the past few seasons.  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 Beetle

Strawberry Rootworm Beetle, photo by James Dill

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

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

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

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Cyclamen Mite Damage

Cyclamen Mite Damage, photo by David Handley

Cyclamen mites:  Plants showing weak growth and yellow, crinkled leaves may be infested with cyclamen mite. Cyclamen mites are very small and reside down in the crown of the strawberry plant feeding on the developing leaves. They are very hard to see, even with magnification.  Miticides such as Thionex®, Kelthane® or Portal® can be effective, but must be applied with lots of water to be sure that the material is carried down into the crowns. If you suspect you have this problem, give us a call.

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

1.  Cultivation:  Following renovation, cultivation between strawberry rows can provide effective temporary control of annual weeds. Several types of cultivators are available which will work well in strawberry beds. Cultivators can also be used to help sweep runners into the plant rows.

2.  DCPA (Dacthal®):  A pre-emergent herbicide used in the early spring, late fall or after renovation. It offers good, short-term control of some annual broadleaf weeds and grasses. It is weak on ragweed, galinsoga, smartweed, shepherd’s purse and mustard. Its action will be improved if worked into the soil by irrigation or light cultivation, and it tends to work best in lighter, warmer soils. This may be used as an alternative to terbacil or napropamide when there is a high risk of plant injury from those products.

3.  Napropamide (Devrinol®):  A pre-emergent herbicide which provides good control of annual grasses, volunteer grains and some broadleaf weeds. It is typically applied just before mulching in the fall. Split applications have become popular due to the loss of other pre-emergent herbicides, e.g. half maximum rate application after renovation or in late summer after desired daughter plants have rooted, and a second half rate application once the strawberry plants are dormant. Napropamide should be activated by irrigation, rainfall or light cultivation within 24 hours of application. Repeated long-term use of this material, i.e. with no crop rotation, may eventually result in poor daughter plant establishment, due to rooting inhibition.

4.  Terbacil (Sinbar®):  An effective pre-emergent herbicide with some post-emergent activity, which should be applied at renovation time – after mowing and tilling the beds, but before new growth begins. A second application can be made in late fall, after the plants are dormant. No more than 6 oz. may be applied in a single application, and no more than 8 oz. may be applied in one season.  An example of one season’s use could be 5 oz. applied at renovation and 3 oz. applied in the late fall, the latter in addition to napropamide or DCPA. Terbacil can cause injury to strawberry plants.  It is important to determine appropriate rates for each location.

5.  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 six weeks of a terbacil (Sinbar®) application to avoid leaf injury.  Sethoxydim should be used in combination with a crop oil concentrate. Do not tank mix with 2, 4-D.

6.  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.

7.  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.

8.  Pelargonic Acid (Scythe®):  A contact herbicide for post-emergent control of most annual weeds and suppression of many perennial weeds. Scythe® will injure or kill strawberries, so applications are made between rows only, with a sprayer shielded to protect the strawberries. This product has a relatively low toxicity and no residual soil activity. It has a strong, unpleasant odor.

9.  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®).

10.  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.

11.  Pendimethalin (Prowl H20®):  A pre-emergent herbicide that may be applied as a band with a shielded sprayer between the rows of strawberries. No weed control will be provided within the plant rows, and contact of this product on the strawberry plants will cause injury. May not be applied within 35 days of harvest.

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

Strawberry Bed Renovation Review

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

Renovating a strawberry bed is basically a thinning process to promote healthy new growth that can support a good crop next spring. While some parts of the following renovation scheme may need to 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®).

Mowing Strawberry Leaves

Mowing Strawberry Leaves, photo by David Handley

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

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

4.  Plant thinning:  For the single matted row system, strawberry plant rows should not be any wider than 24 inches. After mowing off the leaves, till the sides of the rows to narrow the beds back to a width of 12 to 18 inches. Use the wider setting for varieties that tend to throw few runners or any fields experiencing drought stress.  Set the tiller so that it incorporates the mowed leaves and spreads about one inch of soil over the remaining crowns at the same time. This will reduce leaf disease and mite problems, and help stimulate new root growth on the remaining plants.

5.  Pre-emergent weed control:  To control annual weeds, apply terbacil (Sinbar® 80WP) according to label directions (2 to 6 oz. per acre). Be sure to follow all label precautions. To avoid plant injury, do not use terbacil if you do not intend to mow off the leaves. Napropamide (Devrinol®) or DCPA (Dacthal®) may be used as an alternative to terbacil at this time, as described below. If you are not using herbicides, regular cultivation, before weeds are more than 2” tall, will be needed throughout the summer.

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

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

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

NUTRITION:  Following the application of 40 to 60 pounds of actual nitrogen at renovation, another 20 pounds of nitrogen should be applied in mid- to late-August to stimulate flower bud development. One way to determine the nutrient status of strawberry plants during the summer is to have a leaf tissue analysis done. Tissue analysis offers a view of what is happening within the plant, and can spot any nutrient deficiencies. In combination with regular soil tests, tissue analysis will provide a complete picture of a field’s fertilizer needs. For more information about tissue analysis contact: Analytical Lab, 5722 Deering Hall, Rm. 407, University of Maine, Orono, ME 04469-5722, telephone: 581.2945.

Strawberry Irrigation

Strawberry Irrigation, photo by David Handley

Sidedressed Strawberry Planting

Sidedressed Strawberry Planting, photo by David Handley

Pest Management for Day-Neutral Strawberries

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

Male and Female Spotted Wing Drosophila Flies

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

Spotted wing drosophila (Drosophila suzukii) is a new pest which is likely to be a concern for day-neutral strawberries, fall raspberries and blueberries.  This is a small fruit fly, similar to the type that hover around the over-ripe 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. As a result, the fruit quickly rots and has no shelf life.  This insect recently came into the U.S. from northern Asia, and infested Maine berry crops last year. It 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. 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 in a field. Spotted winged drosophila can successfully overwinter here, although it may not build up to damaging levels until late in the summer. We have set out monitoring traps for spotted winged drosophila in fruit plantings around the state to determine the activity of this pest in Maine. However, these traps are unlikely to provide early warning, i.e. when we find them in a trap they are probably already established in the field. We will be alerting growers when we find them in Maine. We have found a few spotted wing drosophila in Maine this season, but not yet in damaging numbers. Products that provide good control of drosophila on strawberries include Delegate®, Brigade®, Danitol®, and malathion. Keeping fields clean of over-ripe and rotten fruit can also help reduce the incidence of this insect. For information on identifying spotted wing drosophila and making your own monitoring traps, visit the Michigan State University’s Spotted Wing Drosophila website.

First Instar Tarnished Plant Bug Nymph

First Instar Tarnished Plant Bug Nymph, photo by David Handley

Tarnished plant bug:  This is one of the most prevalent and persistent pests of day-neutral strawberries, as 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

Product Days to Harvest
Brigade® 0
Pyganic® 0
Assail® 1
Dibrom® 1
Rimon® 1
malathion 3
Thionex® 4

 

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

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

 

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

Gray Mold on Strawberries

Gray Mold on Strawberries, photo by James Dill

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

Visit the 2012-2013 New England Small Fruit Management Guide online for more detailed pest information.

Reminder:  Highmoor Farm Field Day and Summer Tour will be held on Wednesday, July 31, 2013 from 9:00 a.m. to 4:00 p.m. Registration fee is $20 per person, including lunch, and preregistration is strongly encouraged. For more information, visit the Highmoor Farm website or call 207.933.2100. If you are a person with a disability and will need any accommodations to participate in this program, please call Pam St. Peter at Highmoor Farm, 207.933.2100 or TDD 1.800.287.8957 to discuss your needs at least 7 days prior to this event.

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

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

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

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

Sweet Corn IPM Newsletter No. 3 – July 12, 2013

Friday, July 12th, 2013

Sweet Corn

Sweet Corn IPM Newsletter No. 3 – July 12, 2013

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

EARLY SILKING CORN THREATENED BY CORN EARWORM

European Corn Borer also Active, Fall Armyworm Activity Low

SITUATION
Yet more rain in southern Maine
this week has kept fields wet and slowed growth, but more early planted fields are now coming into silk and first harvest is within sight. Insect activity has increased in most locations, and any silking corn is now threatened by both European corn borer and corn earworm.    

European Corn Borer Trap

European Corn Borer Trap, photo by David Handley

European Corn Borer Larvae on Pre-tassel Stage Corn

European Corn Borer Larvae on Pre-tassel Stage Corn, photo by David Handley

European corn borer:  Moth catches continue to be somewhat erratic this week, but most sites had relatively low counts. Silking fields in Gray, North Berwick and Sabattus were over the threshold of 5 moths per week in traps, but all of these sites are also on a spray schedule for corn earworm, so no additional sprays should be required.  European corn borer feeding damage was over threshold in pre-tassel fields in Biddeford, Cape Elizabeth, and Warren this week. We expect to see more late fields exceeding feeding injury in later plantings in the coming week.  Sprays applied at pre-tassel tend to be more effective than whorl or tassel stage sprays, because the larvae are usually more exposed.  

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Corn earworm:  Moths are now being caught at most locations, but many fields do not yet have silking corn and so are not yet threatened by corn earworm. A 6-day spray interval was recommended for early silking fields in Dayton, Gray, No. Berwick, Oxford, Sabattus and Wells. A 5-day spray interval was recommended for silking fields in Farmington, Garland, and Nobleboro, where moth counts were slightly higher. A 4-day spray interval was recommended for one silking field in Cape Elizabeth where the highest moth count of the season was found this week.  

Fall armyworm:  Single moths were caught in two locations this week (Farmington, Lewiston). At this time fall armyworm is not a threat to silking corn. We have not found any fall armyworm feeding damage in younger corn fields, but we anticipate that it will be showing up soon.

Squash vine borer moths were caught in pheromone traps in North Berwick, Biddeford, Gray, New Gloucester and Nobleboro. The threshold of five moths per week was only exceeded in North Berwick, but growers should be aware that the pest is now active and threatens summer squash, winter squash and pumpkins. See the New England Vegetable Management Guide for control options.

Late Blight on Tomato Leaf

Late Blight on Tomato Leaf, photo by James Dill

Late Blight:  Grower and Farm Stand Alert
Late blight has been found on potato plants in northern Maine this week. This follows recent reports of late blight in tomato and potato plantings in New York and Massachusetts and many southern coastal states. Growers should be alert to catch early symptoms and be ready to apply appropriate control measures. Typical symptoms will be water-soaked lesions on the leaves with fine, white cottony mycelium on the undersides. Infections on the stems appear as dark, almost black lesions. Visit Cornell University Cooperative Extension’s web pages for photos of tomatoes and potatoes.  Please report any suspicious symptoms to the Pest Management Office 581.3883 (1.800.287.0279), or email PMO@umext.maine.edu.   

Reminder:  Highmoor Farm Field Day and Summer Tour will be held on Wednesday, July 31, 2013 from 9:00 a.m. to 4:00 p.m. Registration fee is $20 per person, including lunch, and preregistration is strongly encouraged. For more information, visit the Highmoor Farm website or call 207.933.2100. If you are a person with a disability and will need any accommodations to participate in this program, please call Pam St. Peter at Highmoor Farm, 207.933.2100 or TDD 1.800.287.8957 to discuss your needs at least 7 days prior to this event.

Sincerely,

David T. Handley
Vegetable & 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
Auburn 5 2 0 10% No spray recommended (no silking corn)
Biddeford 1 1 0 63% One spray recommended for ECB
Cape Elizabeth I 1 2 0 3% No spray recommended
Cape Elizabeth II 43 2 0 77% 4-day spray interval recommended on all silking corn
Charleston 14 8 0 7% No spray recommended (no silking corn)
Dayton 3 1 0 1% 6-day spray interval recommended on all silking corn
Farmington 4 1 1 5-day spray interval recommended on all silking corn
Dayton 0 0 0 0 No spray recommended
Garland 7 0 0 3% 5-day spray interval recommended on all silking corn
Gray 3 23 0 6-day spray interval recommended on all silking corn
Levant 4 2 0 0% No spray recommended (no silking corn)
Lewiston 0 0 1 2% No spray recommended
Livermore Falls 1 1 0 4% No spray recommended
New Gloucester 1 2 0 2% No spray recommended
Nobleboro 6 2 0 5-day spray interval recommended on all silking corn
No. Berwick 3 13 0 6-day spray interval recommended on all silking corn
Oxford 3 3 0 6-day spray interval recommended on all silking corn
Palmyra 0 8 0 2% No spray recommended
Sabattus 2 12 0 6-day spray interval recommended on all silking corn
Wales 0 0 0 0% No spray recommended
Warren 1 0 0 20% One spray recommended for ECB
Wells I 2 0 0 0% No spray recommended (no silking corn)
Wells II 3 4 0 4% 6-day spray interval recommended on all silking corn

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
http://www.umass.edu/umext/ipm/

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.

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

 

Sweet Corn IPM Newsletter No. 2 – July 8, 2013

Tuesday, July 9th, 2013

Sweet Corn

Sweet Corn IPM Newsletter No. 2 – July 8, 2013

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

EUROPEAN CORN BORER, CORN EARWORM MOTHS ACTIVE

Silking Corn Needs Protection in Early Fields

SITUATION
Warm conditions and lots more rain have kept corn growing, but made it difficult to do any field work, such as spraying or side-dressing. Early fields in some areas are showing silk, and later fields, although uneven, are coming into pre-tassel. Some growers have had difficulty getting onto wet ground to seed their last plantings. The rain also is raising concerns about fertilizer and herbicide leaching.

European corn borer:  Moth catches were irregular this week with about half of the sites having any moths caught, and just a few over threshold for early fields with silking corn. Activity may increase over the next week, as the wet weather might extend the emergence of this first generation of moths. European corn borer feeding damage was over threshold in pre-tassel fields in Biddeford, Cape Elizabeth, Livermore Falls, and Nobleboro this week. One field (No. Berwick) that had both silking corn and was over threshold for moths was also put on a spray program for corn earworm, so no additional sprays were required.

European Corn Borer Damage

European Corn Borer Damage, photo by David Handley

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Corn earworm:  About one half of the fields visited this week had corn earworm moths in pheromone traps. Most of these fields do not yet have any silking corn, so no sprays were recommended. When more than one corn earworm moth is found at a site, all silking corn in the fields should be protected with a spray. Additional sprays are based on the average number of moths caught per week or per night (see table below). Silking fields in Dayton, No. Berwick and Wells were recommended to go on a 6-day spray program for silking corn this week, based on a weekly capture of 3 moths.

Male Fall Armyworm Moth

Male Fall Armyworm Moth, photo by David Handley

Fall armyworm:  We have caught a couple of fall armyworm moths in pheromone traps this week, although the identification has not been confirmed. We have not yet seen any feeding damage from this pest, so no sprays for fall armyworm have been recommended.

Squash vine borer moths are being caught in pheromone traps in southern Maine. The moths lay their eggs at the base of squash or pumpkin plants, and the larvae tunnel into the vines, causing them to wilt and collapse. Entry holes can often be found near the base of the plant.  Sprays can be applied to control the moths and prevent egg-laying. Plow down squash plantings as soon as harvest is complete to prevent borers from overwintering in the field. There is one generation per year. See the New England Vegetable Management Guide for more details.

Japanese beetles are becoming plentiful in southern and mid-state areas. These insects often find their way into corn fields and may feed on the silks of developing ears, causing poor tip fill. Sprays for corn earworm (except Bt’s) will often control Japanese beetle as well.

Japanese Beetle

Japanese Beetle, photo by Edwin Remsberg, USDA

Male and Female Spotted Wing Drosophila Flies

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

Spotted wing drosophila:  We have had our first captures of spotted wing drosophila in New Hampshire and Maine this week. These small fruit flies can cause serious fruit losses in raspberries, blueberries and other soft fruits. The flies will only attack fruit that has begun to ripen, and we don’t expect populations to reach damaging levels for a few weeks. For more information visit the Highmoor Farm website.

Sincerely,

David T. Handley
Vegetable & 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
Auburn 0 7 0 8% No spray recommended (no silking corn)
Biddeford 0 2 0 42% One spray recommended for ECB on pre-tassel corn
Cape Elizabeth I 0 0 0 3% No spray recommended
Cape Elizabeth II 6 12 1 20% One spray recommended for ECB on pre-tassel corn
Dayton 3 1 1% 6-day spray interval recommended on all silking corn
Farmington 2 1 0 2% No spray recommended
Lewiston 0 0 0 0% No spray recommended
Livermore Falls 1 0 0 28% One spray recommended for ECB on pre-tassel corn
New Gloucester 0 0 1 0% No spray recommended
Nobleboro 2 11 0 18% No spray recommended (no silking corn)
No. Berwick 3 13 0 6-day spray interval recommended on all silking corn
Oxford 1 1 0 6% No spray recommended (no silking corn)
Warren 0 0 0 4% No spray recommended
Wells I 2 0 0 0% No spray recommended (no silking corn)
Wells II 3 4 0 4% 6-day spray interval recommended on all silking corn

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
http://www.umass.edu/umext/ipm/

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.

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

Sweet Corn IPM Newsletter No. 1 – June 27, 2013

Friday, June 28th, 2013

Sweet Corn

Sweet Corn IPM Newsletter No. 1 – June 27, 2013

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

2013 SWEET CORN PEST SEASON BEGINS!

Corn Earworm, European Corn Borer Moths Active, Larvae Feeding in Early Corn

The 2013 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, Warren, Monmouth, Wales, Wayne, Oxford, Farmington, Levant, Stillwater, Garland and East Corinth. Pheromone traps have been set up at these farms to monitor the adult (moth) stages of European corn borer, corn earworm and fall armyworm, and we have begun scouting the fields for feeding injury by insect larvae. We will share the information we collected at these sites and management recommendations every week during the season through this newsletter and blog. If you would prefer to receive this newsletter via e-mail, give us a call at 207.933.2100 or send an e-mail message to: pamela.stpeter@.maine.edu.

David Handley Checking Harstack Trap for Corn Earworm Moth

Checking Harstack Trap for Corn Earworm Moth, photo by Edwin Remsberg, USDA

SITUATION
A spell of warm, dry conditions in late April and early May allowed farmers to begin planting corn early through plastic mulch or under row covers. Some of this corn is now in the tassel stage, with a few fields showing some early silk. However, the more recent cool, damp conditions have kept development of later plantings very slow, varying from just a few leaves to early whorl stage. Both European corn borer and corn earworm moths are active in some fields, but their impact is limited if corn is not yet silking.

European Corn Borer Moth

European Corn Borer Moth, photo by David Handley

European corn borer:  We are just starting to find European corn borer moths in the pheromone traps around the state, and activity will likely increase over the next two weeks. These moths are now laying eggs on the undersides of corn leaves. The egg masses are small and look like overlapping fish scales. European corn borer is the only one of the three major insect pests of corn that can successfully overwinter in Maine, and it is usually the first pest to become a significant problem. To monitor corn borer, we scout 100 corn plants in each field, examining twenty plants in a row at five different locations. This sample provides a good estimate of the total amount of injury in a field. In the early stages, European corn borer feeding damage looks like small “pinholes” in the leaves. Corn in the whorl stage 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%. This is because larvae feeding on the later stages are more likely to move into the ears of the plant. On the tassels, feeding damage first appears as chewing and brown waste found in the small florets. After the tassel has emerged from the stalk, 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, reduce the opportunity for larvae to move into the stalks and ears of the plant. Once the larvae are in the stalks they are protected from sprays.

European Corn Borer Damage on Pre-tassel Stage corn

European Corn Borer Damage on Pre-tassel, photo by David Handley

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 Larvin®. When 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. Therefore, if more than five moths are caught during a week in a field with silking corn, a spray will be 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. European corn borer feeding damage has been increasing in recent days and fields in No. Berwick, Sabattus and Livermore Falls were over the damage threshold in pre-tassel fields. Expect more injury to be showing up as more eggs begin to hatch. Early silking fields in Nobleboro and Warren were over the threshold for European corn borer moths caught in pheromone traps and sprays for those fields were recommended.

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Corn earworm:  Pheromone traps are now set up around the state to monitor the arrival of corn earworm. 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 start being 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 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. We have caught a few corn earworm moths in a few southern and coastal locations this week. Only two fields are showing silk now and single moth catches do not warrant a spray.

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 must fly in from southern over-wintering sites, and tend to lay their eggs on the youngest corn available. When the larvae hatch, they chew large, ragged holes in the leaves, and may bore into developing ears. Larvae may 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 will usually be on a spray program for corn earworm when fall armyworm is present, and both insects would be controlled.

Common stalk borer:  This pest can be a problem early in the season, but usually only around the edges of fields. The injury is similar to European corn borer, but the feeding holes are larger, with four or five holes running across the width of a leaf. The larvae are purple colored with white stripes. If high numbers of stalk borer are found in pre-tassel stage corn within the field (not just along the edges), include the injury with corn borer to determine if control is needed. Injury found in whorl stage corn is not a concern because the larvae will leave the plant before ears emerge.

Common Stalk Borer Damage

Common Stalk Borer Damage, photo by David Handley

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).

To learn more about IPM scouting techniques, insect identification and control thresholds, order the fact sheet Managing Insect Pests of Sweet Corn available from the University of Maine Cooperative Extension. Color pictures are provided to help with insect identification, and a chart with spray thresholds is supplied to post near your sprayer for easy reference. You can download a copy from the Pest Management website or call the Pest Management Office at 1.800.287.0279.

High Tunnel Tomatoes

High Tunnel Tomatoes, photo by Danielle Murray

Hold the Date!
Highmoor Farm Field Day and Summer Tour is on Wednesday, July 31, 2013 from 9:00 a.m. to 3:00 p.m. Registration fee is $20.00, including lunch, and preregistration is strongly encouraged. For more information, visit the Highmoor Farm website. Please contact Pam St. Peter at pamela.stpeter@maine.edu or 207.933.2100 to preregister.

Sincerely,

David T. Handley
Vegetable & 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
Auburn 1 25 No spray recommended (no silking corn)
Biddeford 0 5 0 10% No spray recommended (no silking corn)
Cape Elizabeth I 0 2 0 No spray recommended
Cape Elizabeth II 3 20 0 No spray recommended (no silking corn)
Dayton 1 0 0 0% No spray recommended (no silking corn)
Farmington 0 0 0 0% No spray recommended
Lewiston 0 0 0 0% No spray recommended
Livermore Falls 1 0 0 18% One spray recommended for ECB on pre-tassel corn
New Gloucester 0 1 0 0% No spray recommended
Nobleboro 0 26 0 2% One spray recommended for ECB on silking corn
No. Berwick 0 20 0 34% One spray recommended for ECB on pre-tassel corn
Oxford 0 4 0 No spray recommended (no silking corn)
Sabattus 0 33 0 19% One spray recommended for ECB on pre-tassel corn
Wales 0 0 0 0% No spray recommended
Warren 1 7 0 5% One spray recommended for ECB on silking corn
Wells I 0 2 0 0% 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
http://www.umass.edu/umext/ipm/

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.

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

Strawberry IPM Newsletter No. 6 – June 14, 2013

Friday, June 14th, 2013

Strawberries

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

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.

Large Tarnished Plant Bug Nymph

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

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 and Female Spotted Wing Drosophila Flies

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.

Girl with Quarts of Strawberries

 

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.

Strawberry IPM Newsletter No. 5 – June 7, 2013

Friday, June 7th, 2013

Strawberries

Strawberry IPM Newsletter No. 5 – June 7, 2013

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

STRAWBERRY HARVEST BEGINS IN SOUTHERN MAINE

Tarnished Plant Bug Activity High in Some Fields this Week

Situation:  A stretch of fair weather has moved strawberry development along at a more normal pace over the past few days. The heat and storms of last weekend do not appear to have caused any serious issues in strawberry fields we visited. Leaf spot and tarnished plant bugs were the most common problems seen. Harvest is getting underway in some fields that were under row covers this spring. Most fields are now beyond full bloom and most growers are predicting a “normal” opening date for their pick-your-own fields. Overall, most fields appeared very good this week and the crop looks quite promising.

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 on Strawberry Plant

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

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

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

Friday, May 31st, 2013

Strawberries

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

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.

Clipper Damage on Strawberry Plant

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

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

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

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

Friday, May 24th, 2013

Strawberries

Strawberry IPM Newsletter No. 3 – May 24, 2013

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

COOL, WET WEATHER SLOWS STRAWBERRY DEVELOPMENT

Risk of Fruit Rot Diseases Increased

Situation: A very dry spring has quickly turned into a very wet spring for most farms, as nearly a week of cool, rainy weather has put more than two inches of water on the fields, and slowed plant growth significantly. Plant development has changed very little over the past week, with early varieties in southern Maine now moving into or just beyond full bloom, and later varieties coming into bloom. Fields that were under row covers have green fruit up to an inch in size. So ripe fruit should not be far off, if we see some warmer, sunnier weather soon. Insect activity has also been slowed by the weather, but these conditions create a high risk of fruit rot infections, and fields coming into bloom should be protected with fungicides when conditions permit. 

Wet Strawberry Field

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

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

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

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

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

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.

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