Spotted Wing Drosophila Alert: July 22, 2016

July 22nd, 2016 1:34 PM
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 ALERT: JULY 22, 2016

Click on photos to enlarge.

David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist; Frank Drummond, Professor of Insect Ecology/Entomology

We have found a few spotted wing drosophila fruit flies in raspberry and highbush blueberry plantings in Maine over the past week, including single female flies in Limington and Freeport, and two female flies in traps in Buxton and Dresden. In addition, one to two flies have been caught in traps in wild blueberry fields in Hope, Union, Dresden, Washington, Rockland, Deblois, Columbia and Jonesboro.

These are not yet damaging numbers. Research in Maine and other regions suggests that when 6 to 10 flies are caught in a yeast-baited trap in a week, larvae will start appearing in the fruit.

Spotted wing drosophila populations may start to build rapidly in the coming weeks as more food (fruit) becomes available for the flies, especially if conditions remain warm and we get some rain. Now is the time to set out traps, if you haven’t already. Start protective sprays on any berries that have begun to ripen, when more than four spotted wing drosophila flies are caught in a trap, or any larvae are noticed in the fruit. Look for fruit flies hovering around fruit and symptoms of premature fruit decay.

Other states in the northeast have been reporting steady, but very low trap catches over the past few weeks. The lack of a build up of flies to date is thought to be a result of the very dry conditions affecting the region. Research has shown that dry conditions and exposure reduce the number of eggs these insects will lay in the fruit. This supports our recommendations to open up your berry plantings by pruning, especially low growth, as these insects favor dark, moist conditions, close to the ground.

Based on what we know so far about this pest, here are six rules for managing spotted wing drosophila.

  1. Monitor for the flies with traps, and for the larvae in fruit.
  2. Spray regularly and often once flies have been found in the field (1-2/week).
  3. Harvest fruit regularly and often; do not leave any ripe/rotten fruit in the field.
  4. Sort fruit at harvest; do not leave any soft fruit in the container to be sold.
  5. Chill all fruit immediately after harvest to 38ºF (or as close as you can) for at least 12 hours to slow development of any eggs or larvae.
  6. Prune the planting to open up the canopy and create dry, light conditions.

Products that provide good control of drosophila on berry crops include spinosad (Radiant® for strawberries, Delegate® for raspberries and blueberries), Brigade®, Danitol®, malathion and Assail®. Research suggests that adding table sugar to group 4A insecticides, such as Assail®, may improve their effectiveness. The recommended rate would be 1-2 lbs. sugar per 100 gallons of spray. Please check product labels for rates, post-harvest intervals and safety precautions. Keeping fields clean of overripe and rotten fruit will also help reduce the incidence of this insect.

Characteristics of Insecticides for Spotted Wing Drosophila Control

Trade Name Days to Harvest
Blueberry
Days of Residual
Assail® 1 5-7
Malathion 1 5-7
Mustang Max® 1 7
Bifenture® 1 (3 raspberry) 7
Brigade® 1 (3 raspberry) 7
Danitol® 3 7
Exirel® 3 (not for raspberry) 5-7
Delegate® 3 (1 raspberry) 7
Entrust® 3 (1 raspberry) 3-5

A Simple Monitoring Trap for Spotted Wing Drosophila

drosophila trap

Drosophila Trap, photo by David Handley

The trap body is made from a 16 ounce red plastic cup (we use Solo Brand P16RLR). You’ll need one that has a tight fitting lid (we use Solo Brand 626TS). Using a 1/8” hole punch (available through art suppliers), punch about 15 holes in a row around the cup just under the lip about 1/2” apart. Leave about 2” of the diameter of the rim with no holes so that liquid can be poured in and out. Punch a second row of holes just under the first row, to give you a total of 30, 1/8” holes. Use a black permanent marker to paint a 1/2” wide black strip around the cup under the rim, right over the holes you punched. To support the trap, cut a wooden tomato stake down to about 30”. Attach a 4” or larger hose clamp near the top of the stake to act as a cup holder for the trap. (We just punched a hole in the metal band of the hose clamp and attached it to the stake with a flat-headed wood screw.) Place the trap holder in a shady, moist place in or near the fruit planting, with the cup height about 18” off the ground. Fill the trap with 4 to 6 ounces of apple cider vinegar, water + sugar + yeast, or whatever bait you prefer. It is best to add a few drops of unscented soap to break the surface tension of the liquid. Place the lid on the cup to keep rain and critters from getting in, and place the trap in the holder. Adjust the hose clamp so that the trap fits in snugly but the trap holes are not covered up. Empty and re-bait the trap every week. Do not pour out the old bait on the ground near the trap, as this will draw flies away from it.

Other IPM Web Pages
Michigan State University
Pennsylvania State University
University of New Hampshire

David T. Handley
Vegetable and Small Fruit Specialist

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

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

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

Sweet Corn IPM Newsletter No. 5 – July 22, 2016

July 22nd, 2016 10:54 AM

Sweet CornSweet Corn IPM Newsletter No. 5 – July 22, 2016
Click on photos to enlarge.

FALL ARMYWORM THREATENS SILKING CORN

Corn Earworm, European Corn Borer Below Threshold at Most Sites

SITUATION
Warmer temperatures and some much needed (but not enough) rain have helped corn growth over the past week, but scattered hail has damaged some corn and pumpkin crops. Harvest has begun on early mulched or covered plantings in southern Maine. Pest pressure continues to be relatively light, especially for European corn borer and corn earworm. Fall armyworm continues to be the pest of greatest concern at the moment, with high moth counts at many sites and feeding damage becoming more widespread.

European corn borer: Moth catches continue to be very light, with most sites catching no moths this week. No sites were over the 5-moth threshold for silking corn. European corn borer feeding damage was only over the 15% pre-tassel threshold in one field in Bowdoinham.

Corn earworm: Moth counts remain low. Moths were caught in only five locations this week. Three of those, Bowdoinham, Palmyra and Warren had single moths, which does not trigger a protective spray. Two and three moths were caught in New Gloucester and Dayton, respectively, placing those sites on a 6-day interval for all silking corn. Corn not yet in silk does not need to be treated for corn earworm.

Fall armyworm: Moth catches were generally higher this week, with some sites having very high numbers for this early in the season. Sprays for fall armyworm on silking corn were recommended in Biddeford, Cape Elizabeth, one Lewiston site, Monmouth, New Gloucester, Nobleboro, and one Wells site. Feeding damage was observed in several pre-tassel fields, but none exceeded the 15% feeding injury threshold. We expect feeding damage to increase soon, given the high number of moths present.

Adult Fall Armyworm

Adult Fall Armyworm, photo by David Handley

Japanese Beetle

Japanese Beetle, photo by Edwin Remsberg, USDA

 Japanese beetles are now appearing in southern and mid-state areas. These insects often find their way into cornfields and 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.

Spotted wing drosophila: The first capture of a spotted wing drosophila occurred this week in berry fields in southern Maine. These small fruit flies can cause serious fruit losses in raspberries, blueberries and other soft fruits. 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 our Spotted Wing Drosophila blog.

Male and Female Spotted Wing Drosophila Flies

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

Two Squash Vine Borer Moths

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

Squash vine borer alert! We have been catching very high numbers of squash vine borers in pheromone traps in southern and mid-state Maine this week. Counts were well over the 5 moths per week spray threshold at all locations where we are monitoring this pest, including Wells, Biddeford, Hollis, New Gloucester, and Oxford. This pest poses a serious threat to summer squash, winter squash and pumpkins. The moths fly during the day and are often visible resting on squash leaves. They are black and orange and resemble wasps. The moths lay eggs at the base of the plants, and the larvae bore into the stems, causing vines to wilt and eventually collapse. Be on the lookout for vine borer symptoms and protect squash plants if moths or damage are seen. See the 2016-2017 New England Vegetable Management Guide for control options.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Biddeford 0 0 25 11% One spray for FAW on silking corn
Bowdoinham 1 0 1 30% One spray for ECB on pre-tassel corn
Cape Elizabeth I 0 21 0% One spray for FAW on silking corn
Cape Elizabeth II 0 1 47 0% One spray for FAW on silking corn
Charleston 0 2 0 0% No spray recommended
Dayton 3 0 1 0% 6-day spray interval on silking corn for CEW
Hollis 0 0 0 2% No spray recommended
Farmington 0 0 0 1% No spray recommended
Garland 0 2 1 3% No spray recommended
Levant 0 0 0 3% No spray recommended
Lewiston I 0 0 8 2% One spray for FAW on silking corn
Lewiston II 0 0 1 0% No spray recommended
Livermore Falls 0 0 0 10% No spray recommended
Monmouth 0 0 5 One spray for FAW on silking corn
New Gloucester 2 0 21 0% 6-day spray interval on silking corn for CEW
Nobleboro 0 0 12 One spray for FAW on silking corn
No. Berwick 0 2 1 2% No spray recommended
Oxford 0 0 1 2% No spray recommended
Palmyra 1 1 0 1% No spray recommended
Poland Spring 0 0 0 11% No spray recommended
Sabattus 0 0 2 0% No spray recommended
Wales 0 0 0 2% No spray recommended
Warren 1 0 0 5% No spray recommended
Wells I 0 4 1 10% No spray recommended
Wells II 0 0 8 5% One spray for FAW on 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://ag.umass.edu/integrated-pest-management/umass-extension-programs

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

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 15, 2016

July 15th, 2016 11:39 AM

Sweet CornSweet Corn IPM Newsletter No. 4 – July 15, 2016
Click on photos to enlarge.

PEST PRESSURE LIGHT FOR EARLY SILKING CORN

Corn Earworm Below Threshold, but Fall Armyworm still Threatens

UPCOMING AGRICULTURAL EVENTS

Rusted Rooster Farm Grain Walk on Saturday, July 30, 2016 at 3:30 PM
Rusted Rooster Farm, 50 Cates Road, Parkman, ME (Do not use GPS.)
Contact Ellen Mallory at 207.581.2942 or ellen.mallory@maine.edu

Cover Crop Cocktails: Mixing Up Soil Health on Tuesday, July 19, 2016 at 6:00 PM
UMaine Gardens at Tidewater Farm, Farm Gate Road, Falmouth, ME 04105
Contact Lynne Hazelton at 207.781.6099 or lynne.b.hazelton@maine.edu

Small Grain, Cover Crop and Alternative Crop Twilight Meeting on Tuesday, July 19, 2016 at 6:00 PM
UMaine Aroostook Research Farm – meet at UMaine Extension Office, 57 Houlton Road, Presque Isle, ME 04769
Contact Ellen Mallory at 207.581.2942 or ellen.mallory@maine.edu

SITUATION
Cool evening temperatures early in the week and continued dry conditions through much of the state have slowed corn development in most fields, but many early plantings are now in silk. First harvest of corn started under plastic mulch or row covers is not far off. Pest pressure continues to be relatively light, especially for European corn borer and corn earworm. Fall armyworm is the pest of highest concern at the moment, as both moths and feeding damage are becoming more widespread.

European corn borer: Moth catches were very light this week, with only five sites catching any moths, and no sites over the 5-moth threshold for silking corn. European corn borer feeding damage was over the 15% pre-tassel threshold in a field in Sabattus, and in combination with fall armyworm feeding in a field in Poland Spring.

European Corn Borer Moth

European Corn Borer Moth, photo by David Handley

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Corn earworm: Moths were only caught in three locations this week, but all were single moths, which does not trigger a protective spray. Single moths were caught in Cape Elizabeth, Garland and North Berwick. Should the weather pattern shift to bring up storms from the south, we would expect the populations to increase rapidly. But for now the threat from this pest remains very low.

Fall armyworm: Moth catches were spotty around the state this week, with most locations having no moths, and only four sites over the 3-moth threshold for silking corn. Sprays for fall armyworm on silking corn were recommended in Cape Elizabeth, Dayton, one Lewiston site, and New Gloucester. Feeding damage was observed in several pre-tassel fields, but only exceeded the 15% feeding injury threshold when combined with European corn borer feeding in Poland Spring.

Corn leaf aphids may infest corn plants in fields that have not recently been sprayed for other pests. Colonies of these small, bluish-green insects can nearly cover the tassels, stalks and husks. The waste aphids excrete on the plants, called “honeydew” stimulates the development of sooty mold fungus. This dark, slimy fungus coats the surface of the husks, reducing the appearance of the ears. Sprays applied for corn earworm usually control aphids. Sprays for aphids would only be recommended if sooty mold is becoming a problem.

Aphids on Corn Tassel

Aphids on Corn Tassel, photo by Kaytlin Woodman

Potato Leafhopper

Potato Leafhopper, photo by James Dill

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Biddeford 0 1 0 10% No spray recommended
Bowdoinham 0 0 1 5% No spray recommended
Cape Elizabeth I 0 0 0 0% No spray recommended
Cape Elizabeth II 1 0 3 6% One spray for FAW on silking corn
Charleston 0 1 0 0% No spray recommended
Dayton 0 0 3 7% One spray for FAW on silking corn
Hollis 0 0 2 0% No spray recommended
Farmington 0 0 0 3% No spray recommended
Garland 1 0 0 0% No spray recommended
Levant 0 0 0 0% No spray recommended
Lewiston I 0 0 7 4% One spray for FAW on silking corn
Lewiston II 0 0 1 2% No spray recommended
Livermore Falls 0 0 0 2% No spray recommended
Monmouth 0 0 0 No spray recommended
New Gloucester 0 0 3 0% One spray for FAW on silking corn
Nobleboro 0 0 0 0% No spray recommended
No. Berwick 1 4 0 3% No spray recommended
Oxford 0 1 0 2% No spray recommended
Palmyra 0 0 0 1% No spray recommended
Poland Spring 0 0 0 18% One spray for ECB + FAW on pre-tassel corn
Sabattus 0 2 2 15% One spray for ECB on pre-tassel corn
Wales 0 0 0 2% No spray recommended
Warren 0 0 0 5% No spray recommended
Wells I 0 0 0 8% No spray recommended
Wells II 0 0 0 1% 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://ag.umass.edu/integrated-pest-management/umass-extension-programs

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

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 – July 13, 2016

July 14th, 2016 1:23 PM

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

RENOVATION AND WEED MANAGEMENT ISSUE

Time to Get Your Strawberry Beds Ready for Next Year

Time to Manage Pests in Day-Neutral Strawberries

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

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

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

Powdery Mildew

Powdery Mildew, photo by David Handley

Leaf Spot

Leaf Spot, photo by David Handley

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

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

Black Vine Weevil

Black Vine Weevil, photo by David Handley

Strawberry Root Weevil Grub

Strawberry Root Weevil Grub, photo by David Handley

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

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

Strawberry Rootworm Beetle

Strawberry Rootworm Beetle, photo by James Dill

Potato Leafhopper

Potato Leafhopper, photo by James Dill

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

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

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Cyclamen Mite Damage

Cyclamen Mite Damage, photo by David Handley

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

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

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

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

Strawberry Bed Renovation Review

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

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

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

    Mowing Strawberry Leaves, photo by David Handley

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

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

    Strawberry Irrigation, photo by David Handley

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

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

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

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

Pest Management for Day-Neutral Strawberries

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

Spotted Wing Drosophila

Spotted Wing Drosophila, photo by James Dill

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

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

Tarnished Plant Bug

Tarnished Plant Bug, photo by Charles Armstrong

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

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

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

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

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

Gray Mold on Strawberries

Gray Mold on Strawberries, photo by James Dill

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

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

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

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

 


 

Sweet Corn IPM Newsletter No. 3 – July 8, 2016

July 8th, 2016 1:01 PM

Sweet CornSweet Corn IPM Newsletter No. 3 – July 8, 2016
Click on photos to enlarge.

FIRST FALL ARMYWORM MOTHS OF THE SEASON CAUGHT

Corn Earworm More Widespread, but Still in Low Numbers

FREE COVER CROP EVENTS:

Cover Crop Management Walk on Tuesday, July 12, 2016 at 4:00 PM
UMaine’s Highmoor Farm, 52 US Route 202, Monmouth, ME 04259
Contact Lynne Hazelton at 207.781.6099 or lynne.b.hazelton@maine.edu

Cover Crop Walk on Thursday, July 14, 2016 at 5:00 PM
Misty Meadows Farm, Hill Road, Clinton, ME 04927
Contact Caragh Fitzgerald at 207.622.7546 or cfitzgerald@maine.edu

Cover Crop Cocktails: Mixing Up Soil Health on Tuesday, July 16, 2016 at 6:00 PM
UMaine Gardens at Tidewater Farm, Farm Gate Road, Falmouth, ME 04105
Contact Lynne Hazelton at 207.781.6099 or lynne.b.hazelton@maine.edu

SITUATION
Growing conditions continue to be good, but too dry in most of the state this week. More early fields are now coming into silk and many later fields are coming into tassel. European corn borer continues to be active in much of the state, and both fall armyworm and corn earworm are now present in some regions and will threaten silking corn.

European corn borer: Moth catches continue to be spotty; with most sites having no moth captures this week. One Cape Elizabeth site was over the threshold of 5 moths, so a spray was recommended for an early silking field there. European corn borer feeding damage was over the 15% pre-tassel threshold in Bowdoinham and Poland Spring.

Corn earworm: Moths have become more widespread this week, but only single moths have been caught, which does not trigger a protective spray. Also, many locations do not yet have silking corn, so a spray would not be recommended. Single moths were caught in Cape Elizabeth, Dayton, Lewiston and Wells.

Fall armyworm: The first moths of the season were caught in our traps in southern Maine this week. These moths are now laying eggs in young cornfields, and feeding damage is being found in some fields. Fall armyworm caterpillars leave large ragged holes in the corn leaves and lots of sawdust-like waste within the whorl and developing tassels. When feeding damage is found, we combine the number of infested plants with any showing injury from European corn borer, and recommend a spray if the total feeding damage exceeds 15% of the number of plants scouted. In silking fields, fall armyworm larvae may enter the ears through the silk channel, leaving little visible damage to the plant. For that reason, when more than 3 fall armyworm moths are caught in pheromone traps in a week a spray is recommended for all silking corn in a field. Fields in Cape Elizabeth, Dayton, Hollis, Lewiston, New Gloucester, and Nobleboro were over the threshold for silking corn this week. However, only fields in New Gloucester, Cape Elizabeth and Nobleboro had corn in silk, so sprays were not recommended in the other locations. Feeding damage was also noted in pre-tassel corn in Cape Elizabeth, Poland Spring and Warren this week, but only exceeded the 15% feeding injury threshold in Cape Elizabeth.

Fall Armyworm Moths

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

Fall Armyworm Eggs on Corn

Fall Armyworm Eggs on Corn, photo by David Handley

Squash vine borer moths were caught in pheromone traps in New Hampshire this week, according to George Hamilton at the University of New Hampshire Cooperative Extension. Counts were very high and over the 5 moths per week spray threshold at several locations. This pest threatens summer squash, winter squash and pumpkins. Unlike many moths, squash vine borer moths fly during the day. They are black and orange and resemble wasps. The moths lay eggs at the base of squash plants. The larvae bore into the base of the plants, causing vines to wilt and eventually collapse. Growers with squash in southern Maine should be on the lookout for vine borer symptoms and protect squash plants if moths or damage are seen. See the 2016-2017 New England Vegetable Management Guide for control options.

Two Squash Vine Borer Moths

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

Squash Vine Borer Larva

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Biddeford 0 2 0 11% No spray recommended
Bowdoinham 0 0 0 29% One spray for ECB on pre-tassel corn
Cape Elizabeth I 1 0 3 18% One spray for ECB + FAW on pre-tassel corn
Cape Elizabeth II 1 6 13 8% One spray for ECB + FAW on silking corn
Dayton I 1 0 3 1% One spray for FAW on silking corn
Hollis 0 0 2 0% No spray recommended
Farmington  0 0 0 3% No spray recommended
Lewiston I 0 0 2 0% No spray recommended
Lewiston II 1 0 3 4% No spray recommended (no silking corn)
Livermore Falls  0 0 0 7% No spray recommended
Monmouth  0 0 0 No spray recommended
New Gloucester 0 0 3 0% One spray for FAW on silking corn
Nobleboro 0 0 3 3% One spray for FAW on silking corn
No. Berwick 0 0 0 13% No spray recommended
Oxford 0 1 0 2% No spray recommended
Poland Spring 0 1 1 29% One spray for ECB + FAW on pre-tassel corn
Sabattus
Wales
Warren 0 0 0 8% No spray recommended
Wells I 0 4 1 5% No spray recommended
Wells II 1 0 1 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://ag.umass.edu/integrated-pest-management/umass-extension-programs

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

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 1, 2016

July 1st, 2016 12:50 PM

Sweet CornSweet Corn IPM Newsletter No. 2 – July 1, 2016
Click on photos to enlarge.

FIRST CORN EARWORM MOTH OF THE SEASON CAUGHT

European Corn Borer Feeding in Pre-Tassel Fields

SITUATION
Growing conditions for corn continue to be good. However, drought stress has been noted in some fields with light soils that have not been irrigated. Rains earlier in the week have helped relieve the dry conditions, but most fields could still benefit from more water. Early fields in southern Maine are coming into tassel, and a few fields started under plastic or row covers are now in silk. European corn borer are active in cornfields in much of the state and may pose a threat to early silking fields; which growers often spray lightly, if at all, assuming these pests aren’t yet present in damaging numbers.

European corn borer: We continue to set up pheromone traps for corn borer moths this week, but in sites where traps were set up last week, catches have been spotty, with half of the sites having moths. A field in Sabattus was over threshold of 5 moths, so a spray was recommended for an early silking field there. Once corn reaches the silk stage, sprays may be based on the number of corn borer moths caught in pheromone traps rather than feeding injury. European corn borer feeding damage was only over the 15% pre-tassel threshold at one field in Poland Spring. Otherwise, feeding damage has been fairly light.

European Corn Borer Moth

European Corn Borer Moth, photo by David Handley

European Corn Borer Trap

European Corn Borer Trap, photo by David Handley

Corn earworm: The first moth of the season was caught in a pheromone trap in Lewiston this week. However, there was no silking corn at that site, so no spray was recommended. No moths were caught at any other sites, and most fields do not yet have any silking corn that could be threatened by this pest. 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).

Fall armyworm: No moths have been captured in our pheromone traps this week, and no feeding damage has been reported. This is usually the last major corn pest to arrive in Maine from southern overwintering sites.

drosophila trap

Drosophila Trap, photo by David Handley

Spotted wing drosophila: The first captures of a spotted wing drosophila are being reported from southern New England this week. These small fruit flies can cause serious fruit losses in raspberries, blueberries and other soft fruits. The flies only attack fruit that has begun to ripen. We will be setting out traps for spotted wing drosophila in Maine berry fields over the next two weeks. We don’t expect populations to reach damaging levels for at least a few more weeks. For more information visit our Spotted Wing Drosophila web blog.

Post-emergent weed control in sweet corn
In some situations, using herbicides after the corn has emerged can offer improved weed control because you can select a product that will better target the weeds that are prevalent in a particular field. Post-emergent products also give growers additional options when pre-emergent strategies have not worked well. Some post-emergent herbicide options include: bentazon (Basagran®), halosulfuron (Sandea®), tembotrione (Laudis®), topramezone (Impact®), and 2,4-D (Amine 4®). Be sure to follow all product label instructions and precautions. For detailed information on how and when to use these options, see the 2016-17 New England Vegetable Management Guide.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Biddeford 11% No spray recommended
Cape Elizabeth I 0% No spray recommended
Cape Elizabeth II 4% No spray recommended
Dayton I 0% No spray recommended
Dayton II 0% No spray recommended
Farmington 0 0 0 1% No spray recommended
Lewiston I 1 1 0 4% No spray recommended (no silking corn)
Lewiston II 0% No spray recommended
Livermore Falls 0 0 0 3% No spray recommended
New Gloucester 0% No spray recommended
Nobleboro 0 0 0 1% No spray recommended
No. Berwick 9% No spray recommended
Oxford 0% No spray recommended
Poland Spring 23% One spray for ECB on pre-tassel corn
Sabattus 0 9 0 9% One spray for ECB on silking corn
Wales 0% No spray recommended
Warren 0 4 0 5% No spray recommended
Wells I 0% No spray recommended
Wells II 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://ag.umass.edu/integrated-pest-management/umass-extension-programs

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

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 24, 2016

June 24th, 2016 2:37 PM

Sweet CornSweet Corn IPM Newsletter No. 1 – June 24, 2016
Click on photos to enlarge.

2016 SWEET CORN PEST SEASON BEGINS!

European Corn Borer Active in Early Fields

The 2016 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 are being set up at these farms to monitor the adult (moth) stages of European corn borer, corn earworm and fall armyworm, and we have started scouting corn fields for feeding injury by insect larvae. The information we collect will be shared through this newsletter along with management recommendations. We will share the information we collect at these sites along with 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.

SITUATION
A dry start to the season allowed many farmers to get started planting early, but cool temperatures have moderated plant growth. Early plantings in southern Maine and plantings started under plastic or row covers are just starting to tassel, and we may see some silking corn next week. While we are just setting up pheromone traps for moths, European corn borer larvae are already active. Growers with early corn should be on the lookout for feeding damage in their fields.

European Corn Borer Damage on Pre-tassel Stage corn

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

European corn borer: Pheromone traps for moths are now being set up in the grassy borders around cornfields. We have started scouting pre-tassel fields in southern Maine and found some feeding in the leaves and emerging tassels. The larvae are very small and recently emerged from egg masses laid over the past two weeks. The egg masses are small and look like a clump of overlapping fish scales on the undersides of corn leaves. European corn borer overwinters in Maine, and is usually the first pest to become a significant problem. To monitor corn borer, we scout 100 corn plants in each field, examining twenty plants in a row at five different locations. This provides a good estimate of the total amount of injury in a field.

In the early stages, European corn borer feeding damage looks like small “pinholes” in the leaves. Whorl stage corn only needs to be sprayed if fresh feeding injury is found on 30% or more of the plants scouted in a field. Once the corn reaches the pre-tassel stage, the control threshold is lowered to 15% because larvae feeding on the later stages are more likely to move into the ears. On the tassels, feeding damage first appears as chewing and brown waste found in the small florets. After the tassel has emerged from the 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. 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®.

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

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Corn earworm: We are now setting up pheromone traps around the state for corn earworm moths. Corn earworm generally appears in Maine in early July, but the actual date varies greatly. The arrival of this pest is only a concern for fields with corn in the silk stage. Fields not yet in silk do not need to be protected from corn earworm. When corn earworm moths 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 or tassels of younger corn. The larvae will feed on the foliage and tassels, similar to armyworm, until the ears become available. When larvae are found feeding on younger corn, the damage is accounted for, along with any borer or armyworm damage, to determine if a spray is warranted.

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.

Fall Armyworm Moths

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

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 Cooperative Extension Publications website or call the Pest Management Office at 1.800.287.0279.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://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. 4 – June 10, 2016

June 20th, 2016 1:04 PM

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

SPIDER MITE AND TARNISHED PLANT BUG NUMBERS CLIMB

Southern Fields Nearing Harvest

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

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

Large Tarnished Plant Bug Nymph

Third Instar Tarnished Plant Bug Nymph, photo by David Handley

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

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

Gray Mold on Strawberries

Gray Mold on Strawberries, photo by James Dill

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

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

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

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

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

 

 

 

 

Strawberry IPM Newsletter No. 3 – June 3, 2106

June 20th, 2016 12:25 PM

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

STRAWBERRY INSECT AND DISEASE PRESSURE LOW

Spider Mites Over Threshold in Several Fields

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

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

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

Clipper Beetle on Strawberry Bud

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

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

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

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

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

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

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

 

 

 

 

Strawberry IPM Newsletter No. 2 – May 27, 2016

June 20th, 2016 12:03 PM

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

STRAWBERRY PESTS ENJOYING EARLY BLOOMING FIELDS

Clippers, and Spider Mites Over Threshold this Week

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

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

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

Clipper Injury

Clipper Injury, Photo by David Handley

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

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

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

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

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

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

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

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

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

Angular Leaf Spot

Bacterial Angular Leaf Spot, Photo by David Handley

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

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

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

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