For full page print version, please see link at the bottom.

Strawberry bud weevil or “clipper”:  Most fields in southern Maine are well beyond the stage when clipper could pose a significant threat.  However, if you have very late blooming varieties or you are far enough north that many of the plants still have unopened buds, you should continue to scout for clipper damage.  One field was over threshold this week but the damage was occurring on small, tertiary and quaternary buds, with the primary and secondary already opened and undamaged, so the payoff of applying a spray was questionable.

Reminder to Raspberry Growers:  Strawberry clipper will move onto raspberry buds after strawberry bloom.  Check raspberry flower clusters for clipped buds and live clippers.  Insecticide sprays to control raspberry fruit worm adults, which are also active at this time, should provide some control of clipper as well.  Products registered for clipper on raspberries include Brigade®, Sevin XLR Plus® and Aza-Direct®.

Tarnished plant bugs were again few and far between in fields this week.  We have seen a few nymphs in southern Maine fields, but not enough to exceed the control threshold.  Fields still in bloom should continue to be scouted for tarnished plant bugs nymphs until petal fall.  Remember that this insect can also be a significant problem on day-neutral strawberry varieties, which flower and fruit in the late summer and fall.  This is when the insect is at its peak population, so feeding pressure on the crop can be intense.  Pay close attention to days to harvest restrictions on any insecticide used for tarnished plant bugs on day-neutral varieties, because often you will have to protect flowers at the same time as the fruit is ripening.

Third Instar Tarnished Plant Bug Nymph, photo by David Handley

Two-spotted spider mites:  Strawberry fields continue to be relatively free of spider mites this spring.  Only two fields scouted this week showed the presence of mites, and only one of those was above the threshold of 25% of leaves infested.  Should we get a warmer, dryer stretch of weather mite populations could bounce up, so it is important to keep scouting right up until harvest.

Two-spotted Spider Mites, photo by David Handley

Sap beetles are sometimes a problem as we start harvesting berries.  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. Brigade®, Assail®, 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.

Sap Beetle, photo by New York State Agricultural Experiment Station

Diseases:  Fields with ripening fruit should have received the needed two to three bloom sprays for protection against gray mold by now.  Fields still in the bloom to late bloom stage may need a final spray to protect the blossoms from infection by spores, especially if they have been through some of the recent rain shower activity.

Gray Mold on Strawberries, photo by James Dill

Powdery mildew:  This appears to be the most prevalent disease in strawberry fields this year.  Leaf cupping, reddening of leaf stems and fruit stems, and white, powdery fungal growth on the undersides of leaves has been seen to some degree in nearly every field.  Good growing conditions for the fungus have made it challenging to keep in check.  If you still have a bloom fungicide spray that should be applied, consider using a material that will also help control powdery mildew, such as captan, Topsin-M® or Pristine®.

Leaf spot infections are becoming more common in strawberry fields this week.  The spots usually appear on older leaves first, as small purple or red spots with white centers.  Leaf scorch has also been noted in a couple of fields (‘Darselect’ is quite susceptible to this).  The spots are smaller in the case of scorch, and lack the white centers.  Spots may coalesce to turn the leaves purple and necrotic, leading to the death of the leaf and weakening of the plant.  Many strawberry varieties have at least partial resistance to leaf spot and leaf scorch. Fungicides registered for leaf spots include captan, Topsin-M®, Syllit®, Cabrio®, Nova® and Pristine®.

Leaf Spot, photo by David Handley

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

Birds, specifically cedar waxwings will be moving into fields to start feeding on ripe fruit, if they haven’t already.  These birds can 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.  Usually, they are discouraged 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.  However, the permit is good for one year, so if you have problems this season, you may consider applying for a permit this winter, which would allow you an option to kill birds, if necessary, next season.  The Wildlife Damage Office has recommendations for managing birds in crops, and also has some control options available through their office.  For more information on permits or bird control contact the office in Augusta at 207.629.5181.  The office is located in the Capital West Business Center at 79 Leighton Road in Augusta.

Cedar Waxwing, photo by Cornell University

Bird Damage on Strawberry, photo by David Handley

Hold the Date!
Highmoor Farm Field Day, Thursday, July 21, 2011.

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

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

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

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

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

For full page print version, please see link at the bottom.

Strawberry bud weevil or “clipper”:  Although we have seen increased clipper activity in most of the fields scouted this week, many fields in southern Maine are beyond the growth stage (blossoms in bud stage) where clipper poses a threat.  Once beds are in full bloom, clipper will not be able to cause economic harm.  However, fields not yet in full bloom should continue to be scouted.  Three fields were over the control threshold of 1.3 or more buds clipped per 2 foot of row length this week.

Tarnished plant bugs continue to be relatively scarce in the fields scouted this week.  While we still have not found nymphs in most of the fields scouted, we did find them in some fields, and one field was over the threshold of 4 or more infested flower clusters per 30 sampled.  Warmer weather will likely bring about an increase in tarnished plant bug activity in the coming days, and strawberry flowers can remain susceptible to feeding injury even after petal fall.  Products registered for controlling tarnished plant bug include Brigade®, Danitol®, Malathion®, Thionex® and PyGanic®.  Bees and other pollinators are also active in your fields now, so apply pesticides at night when they are less active and use materials that pose the least threat to pollinators.  See page 115 of the 2010-2011 New England Small Fruit Pest Management Guide for more information (http://www.umass.edu/fruitadvisor/pdf/2010NESmallFruitGuide.pdf).

First Instar Tarnished Plant Bug Nymph, Photo by David Handley

Two-spotted spider mites:  In spite of a few warm days, the mostly cool, damp conditions appear to be keeping spider mites in check.  Most fields had no mites in our samples and those that had mites were well below the spray threshold of 25% of leaves infested.  Warmer weather will stimulate mite activity, so it is important to keep scouting in the coming weeks.

Spittlebugs:  We have been finding spittlebug masses in some strawberry beds this week.  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.  Start scouting for spittlebugs when the plants are at about 10% bloom.  Randomly inspect five one-square foot areas per field every week.  On hot, dry days 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 the frothy spittle masses.  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®.

Spittlebug, Photo by David Handley

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

Slug on Strawberry, photo by James Dill

Diseases:  Most early fields are at the stage for a second application of fungicide to protect against gray mold.  Later blooming fields may now be ready for their first application.  Two to three sprays are generally required to provide good protection against Botrytis.  However, if rainfall exceeds more than one inch between sprays and wet conditions are prevalent, additional sprays may be required.

Powdery mildew:  We continue to find powdery mildew symptoms in nearly all fields scouted this week.  Conditions have apparently been just wet and warm enough to encourage its development in susceptible varieties.  Leaf cupping, purple leaf and flower stem lesions are being seen on many plants.  Mildew infections weaken plants and can reduce yield the following year.  Some varieties are more susceptible than others, for example Annapolis and Sable are quite susceptible, while Jewel, Mira and Mesabe are thought to be resistant.  Captan, Topsin-M®, Pristine®, Cabrio®, Quintec®, Procure® and Rally® are presently registered to control powdery mildew.

Powdery Mildew, photo by David Handley

Bacterial angular leaf spot:  We have not yet found plants with symptoms of angular leaf spot (Xanthomonas fragariae) this spring, but the cool wet conditions may encourage this disease if it is present in your field.  Angular leaf spot is a bacterial disease characterized by small, translucent or “water-soaked” leaf spots that occur between the veins.  The spots coalesce, turn yellow, reddish and eventually black.  The symptoms start on the lower leaves and move up as bacterial spores are splashed by rain or irrigation water.  Infection of the calyxes may also occur, resulting in blackened berry stems and caps.  Irrigation for frost protection can encourage the development of this disease, although watering has not been needed yet for frost this spring.  Copper-containing chemicals, such as Kocide®, Cuprofix®, and Bordeaux are the only materials that have some effect on this disease. Some labels suggest adding lime as a “safener” to reduce the risk of crop injury.  Spray applications need to begin before bloom to prevent spread of bacteria on the leaves before they spread to berry caps.  Application of copper sprays after bloom can result in fruit injury and is not recommended.  Therefore, most fields are now past the stage where copper should be considered.  Recent research suggests that hydrogen dioxide (OxiDate®) may also have some activity against angular leaf spot when used on strawberries as part of a gray mold management program.

Bacterial Angular Leaf Spot, Photo by David Handley

Don’t Forget: Twilight Meeting in Lewiston on June 8
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association are sponsoring a growers meeting at R. Belanger & Sons Farm in Lewiston on Wednesday, June 8^th at 5:30 p.m.  Come tour the new packing and storing facility, get a look at look at early vegetables and discuss the strawberry season ahead.  One pesticide applicator re-certification credit will be available.  Belanger and Sons Farm is located at 262 Cotton Road in Lewiston.  Directions:

From the north:  On the Maine Turnpike I-95, take Exit 80 toward Rt. 196/Lewiston.  Merge right onto Alfred Plourde Pkwy.  Take ramp onto Rt. 196, E. Lisbon St., then slight right onto Pleasant St., then slight left onto Commercial St.  Travel 2 miles on Ferry Rd.  Turn left onto Cotton Rd.  The farm is on the left.

From the south:  On the Maine Turnpike I-95, take Exit 80 toward Rt. 196/Lewiston.  Turn right onto Alfred Plourde Pkwy.  Turn left onto River Rd. and travel 2 miles.  Continue onto Ferry Rd., then turn right onto Cotton Rd.  The farm is on the left.

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.

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

For full page print version, please see link at the bottom.

Strawberry bud weevil or “clipper”:  Although there are flower buds aplenty around the state this week, we have seen remarkably little indication of clipper activity.  We have seen just a few live clippers and several clipped buds; but none of the fields we scouted were over the spray threshold of more than one clipped bud per two feet of row length.   Therefore early blooming fields may not require any spray for clipper this spring, as they won’t cause damage after bloom.  However, later blooming varieties may begin to show more damage in the coming days and should continue to be scouted for clipped buds.

Clipper Beetle on Strawberry Bud, Photo by James Dill

Clipper Injury, Photo by David Handley

Tarnished plant bugs were also scarce in the fields scouted this week.  Although we did see numerous adults in some fields we have still not found any immature stage bugs, or nymphs, infesting strawberry flower clusters.  While the cool, wet conditions may have delayed the emergence of the nymphs, the presence of the adults suggests that they may soon become a concern.  The nymphs are small, active, yellow-green insects, and it is important to scout for them often, as they can show up quickly in warm weather.  For control options, review last weeks issue of this letter or see the 2010-2011 New England Small Fruit Pest Management Guide (http://www.umass.edu/fruitadvisor/pdf/2010NESmallFruitGuide.pdf).

First Instar Tarnished Plant Bug Nymph, Photo by David Handley

Two-spotted spider mites have only been found in a few fields this week, mostly on plants that were under row covers.  However, none of the fields scouted were over the threshold of 25% or more of leaves infested.  Mites tend to exhibit little growth under cool, wet conditions, so our recent weather has probably kept them in check.  It is likely that overwintering adults are now laying eggs and that we will start seeing more mites once we get a stretch of warm, dry weather.

Cyclamen mites:  We have seen some plants showing the crinkled leaves characteristic of cyclamen mite damage, but have only found live mites in one field, which was also infested last year.  We will continue to keep a lookout for this pest as it may become more prevalent once the temperatures start to rise.

Cyclamen Mite Damage, photo by David Handley

Root weevil management
We have found strawberry root weevils in three fields this spring, so apparently they came through the winter very well.  The infested plants appear weak and stunted, and often wilt on hot days.  Digging under the plants reveals the small (1/4 -1/2”) crescent-shaped grubs.  The grubs usually begin to pupate when the plants are in bloom, but this week we found just small and large grubs and no pupae.  Control of this pest is difficult. It is too late to apply the registered insecticide (Platinum®) for the grubs in fruiting fields, as it requires a 50 day pre-harvest interval.  If you intend to keep an infested field for another year, you can apply Brigade® insecticide for the adult weevils once they have emerged and begin feeding on the foliage, usually in mid-July just before renovation.  In order to maximize effectiveness it is recommended that you use the full labeled rate and apply the material at night when the weevils are most active.

Strawberry Root Weevil Grub, photo by David Handley

Diseases:  Many fields have received an early bloom stage fungicide spray to protect them from spores of Botrytis cinerea, the fungus that causes gray mold.   Two to three sprays of fungicide during bloom are typically required to provide good protection against this disease.  Generally an early bloom (5-10%) spray, a full bloom spray and a third cover at late bloom to petal fall will provide good control of this disease.  However, if rainfall exceeds more than one inch between sprays and wet conditions are prevalent, additional sprays may be required.  Alternatively, if conditions remain very dry after the second spray, then a third spray may not be necessary.

Leather rot (Phytopthora cactorum) continues to be a threat if you have had very wet conditions during bloom, especially if there has been standing water in the field.  Foliar sprays of Aliette®, Agri-Phos® or Phostrol® (similar to Aliette®) may also provide control.  Sprays should be applied during bloom and fruit development.

Red stele root rot:  We have seen mild symptoms of red stele in two fields this spring.  Given the wet, cool soil conditions this spring, infections were likely.  However, symptoms appeared very late and should conditions become warm and dry, there shouldn’t be much further spread this year.  If infested fields are going to be carried over, an application of Ridomil Gold®, Alliette® or Phostrol® should be applied in the fall.  Foliar sprays of Alliette® or Phostrol® can still be applied this spring.

Powdery mildew:  This fungus disease has been observed in nearly all fields this week, although symptoms thus far have been mild.  Leaf cupping and pinkish purple leaf and flower stem lesion symptoms could be seen on susceptible varieties.  When planning protective bloom sprays for gray mold, consider using a fungicide that will also control powdery mildew, such as captan + Topsin-M®, or Pristine®.

Powdery Mildew, photo by David Handley

Vegetable & Berry Growers Twilight Meeting on June 8, 2011
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a growers meeting at R. Belanger & Sons Farm in Lewiston on Wednesday, June 8^th at 5:30 p.m.  We will tour Rick Belanger’s new packing and storing facility designed to meet new GAP certification standards, look at some early vegetables and look over the strawberry plantings while discussing pest management strategies for the season ahead.  One pesticide applicator re-certification credit will be available for attending the meeting.  Please join us!  Belanger and Sons Farm is located at 262 Cotton Road in Lewiston.  Directions:

From the north:  On the Maine Turnpike I-95, take Exit 80 toward Rt. 196/Lewiston.  Merge right onto Alfred Plourde Pkwy.  Take ramp onto Rt. 196, E. Lisbon St., then slight right onto Pleasant St., then slight left onto Commercial St.  Travel 2 miles on Ferry Rd.  Turn left onto Cotton Rd.  The farm is on the left.

From the south:  On the Maine Turnpike I-95, take Exit 80 toward Rt. 196/Lewiston.  Turn right onto Alfred Plourde Pkwy.  Turn left onto River Rd. and travel 2 miles.  Continue onto Ferry Rd., then turn right onto Cotton Rd.  The farm is on the left.

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

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

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

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

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

For full page print version, please see link at the bottom.

The best way to manage strawberry pests is to scout your own fields regularly and often.  Start now, if you haven’t already.  You should be able to identify the major pests and their damage, and be able to determine if control measures are necessary.  To properly scout your fields you may want a copy of the Strawberry Production Guide for the Northeast, Midwest and Eastern Canada.  This contains detailed information on strawberry pest identification and monitoring, and also provides information on all other aspects of strawberry production.  It may be purchased for $45.00 per copy from the University of Maine Cooperative Extension.  You can order it online at: http://extensionpubs.umext.maine.edu/.  You should also have a copy of the 2010-2011 New England Small Fruit Pest Management Guide, which contains the latest information on management control options for the major strawberry pests as well as scouting information.  Color pictures of the important strawberry pests are now also printed in the 2010-2011 New England Vegetable Management Guide.  Call or e-mail us if you are interested in purchasing copies of these guides.

Situation:  Early varieties and plants that were under row covers are now showing a few king blossoms in southern and mid-state fields, but development will continue to be slow until temperatures finally start to rise.  So far, there have been no reports of significant winter injury, as we had few days of severe cold and good snow cover for most of the winter.  I have seen a little bit of frost injury on some very early flowers that were under row covers, but so far it has not been a difficult season for frost.  There is certainly the threat of frost injury for at least another two weeks, so pay close attention to weather reports and be ready to protect the buds and blossoms should the temperature dip below freezing.  Bear in mind that if fields need to be irrigated for frost repeatedly in the coming weeks we will increase the risk of bacterial angular leaf spot becoming a problem.

Bacterial Angular Leaf Spot, Photo by David Handley

Strawberry bud weevil or “clipper” should start becoming active in strawberry fields as more flower buds emerge.  I haven’t found signs of adult feeding activity (holes in flower petals) yet, as the wet weather has probably slowed them down, but expect clippers to be active in the coming days as more flower buds become available.  The clipper is a small weevil, which girdles strawberry flower buds, causing them to dry up and fall off the flower stalk.  Scout for damage by counting the number of clipped buds in two feet of row length at five different locations in a field.  If the average number of clipped buds per two-foot sample exceeds 1.2, or if live clippers are found, control measures are recommended.  Damage is usually first noticed at the edges of the field.  Border sprays may be effective in keeping this insect from becoming a problem in larger fields.  Fields with a history of clipper problems will typically exceed threshold nearly every year.  Insecticide options for clipper include Lorsban®, Brigade®, Sevin® and PyGanic®.

Feeding Signs of Strawberry Clipper, photo by David Handley

Tarnished plant bugs have not yet been observed in the field, but these are hard to find on wet plants.  The damp weather may reduce their egg-laying success, however, so let’s hope we’ll not see too much pressure on the flowers as the weeks progress.  Once the eggs do start to hatch, we’ll start seeing the immature bugs, or nymphs, feeding in the flowers.  The nymphs are small, active, yellow-green insects.  It is important to scout for the nymphs regularly, as they can show up quickly in warm weather.  Tarnished plant bugs feed on the open strawberry flowers, causing the berries to have seedy ends.  To scout for this insect shake 30 flower clusters (six clusters in five different locations) over a plate.  If four or more of the clusters out of the 30 sampled have any nymphs, control measures should be taken.  Be on the alert and scout your fields now! Insecticide options for tarnished plant bug include malathion, Brigade®, Danitol®, Thionex® and PyGanic®.

Tarnished Plant Bug Adult, photo by David Handley

Cyclamen mites:  Plants showing weak growth and yellow, pinkish or blackened, crinkled leaves may be infested with cyclamen mite.  Cyclamen mites are very small, smaller than spider mites, and reside in the crown of the strawberry plant feeding on the developing leaves and flower buds.  They are very hard to see, even with magnification.  Infested plants have shrunken distorted leaves and flower stalks, and produce few, if any, marketable fruit.  Miticides such as Thionex® or Kelthane® and Temprano® can be effective, but must be applied in lots of water to be sure that the material is carried down into the crowns where these mites reside. I already have found cyclamen mites in one field this week, and many fields were infested last year, so be on the look out for these symptoms.

Cyclamen Mite Damage on Strawberry Plant, photo by David Handley

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

Root weevil management
Given the relative mild winter we should expect to see good survival of strawberry root weevil and black vine weevil in fields that were previously infested.  Infested plants appear week and stunted, usually in somewhat circular patches in a field.  Digging under the plants will reveal small (1/4 -1/2”) crescent-shaped legless grubs.  Typically, the grubs begin to pupate when the plants are in bloom, but we have seen both small grubs and pupae already this spring.  A soil drench of Platinum® (thiamethoxam) insecticide during the spring and/or fall when the grubs are active in the soil can provide control.  However, Platinum® has a 50 day pre-harvest interval, so it is too late for applications in most fruiting fields this year.  Platinum® may also be used as a pre-plant or planting treatment for root weevils.

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

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

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

Leather rot (Phytopthora cactorum) may also become an issue when you have a lot of water in the fields during bloom and fruit development, especially if you did not get mulch on the fields last fall and the plants are on bare, wet soil.  Leather rot is best controlled by growing strawberries in well-drained soil and applying straw mulch between the rows to prevent berries from touching the soil and reduce any soil from splashing up onto the berries.  Foliar sprays of Aliette®, Agri-Phos® or Phostrol® (similar to Aliette®) may also provide control.  Sprays should be applied during bloom and fruit development.

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

Powdery mildew:  This fungus disease has been starting to show up as purple or red blotches on the leaf petioles and flower stems in some fields.  Most of us are more familiar with the later symptoms of upward curling of the leaves and white, powdery growth on the undersides of the leaves.  Check your fields for pinkish purple leaf and flower stem lesion symptoms now.  Abound®, captan, Pristine®, Cabrio®, Topsin-M® and JMS Stylet oil® are presently registered to control powdery mildew.

Vegetable & Berry Growers Twilight Meeting on June 8, 2011
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a growers meeting at R. Belanger & Sons Farm in Lewiston on Wednesday, June 8^th at 5:30 p.m.  We will tour Rick Belanger’s new packing and storing facility designed to meet new GAP certification standards, look at some early vegetables and look over the strawberry plantings while discussing pest management strategies for the season ahead.  One pesticide applicator re-certification credit will be available for attending the meeting. Please join us!  Belanger and Sons Farm is located at 262 Cotton Road in Lewiston.  We’ll provide more detailed directions in a future issue.

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. 

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

For full page print version, please see link at the bottom.

Renovation and Weed Management Issue

Early Harvest Offers Opportunity for Early Renovation

The night of May 10 quickly changed the outlook for the 2010 Maine strawberry crop.  A warm, dry spring led to a very early bloom and greatly increased the risk of frost injury to the flowers. On the night of May 10 temperatures in some fields dropped into the low 20’s, despite predictions of temperatures in the low to mid 30’s.  Growers who were alerted to the situation in time and could irrigate their fields suffered relatively little damage.  For growers who were not able to water, most of the primary and secondary blossoms were lost, leading to significant reductions in yield and a delay in ripening.  However, most growers who saw high levels of blossom damage in their fields still had a salable crop this season, although fruit size and total yield was reduced.

Frost Injury to Flowers and Leaves, Photo By David Handley

Insect pressure from both tarnished plant bug and strawberry clipper was relatively light this spring.  Cyclamen mites, and lately potato leafhopper have been an issue in some fields, causing plant stunting and poor growth.  Customers appear to have been alerted to the early harvest season, as pick your own fields were generally doing good business and pre-picked sales were very strong.

Bed renovation should begin as soon after harvest as possible, and our early season this year should allow us to start renovation a bit sooner than normal.  Early renovation allows more time for runner plant development, leading to 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.

Strawberry Bed Renovation Review
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 heavy crop next spring.  While some of the general 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®).

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 1½ 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.

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 1½ inches of water per week during the growing season.

Strawberry Irrigation, photo by David Handley

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 may be applied in mid- to late-August to stimulate flower bud development.

Sidedressed Strawberry Planting, photo by David Handley

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, Web page: http://anlab.umesci.maine.edu/ .

Diseases:  Foliar diseases should be monitored in your fields by regularly examining leaves.  We have seen all of the common leaf diseases in fields this spring and 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 2010-2011 New England Small Fruit Pest Management Guide for detailed descriptions of these diseases and their management.

Leaf Scorch, 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®) 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 Pest Management Guide for sources.

Black Vine Weevil, photo by David Handley

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.

Strawberry Rootworm Beetle, 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®.

Potato Leafhopper, photo by New York State Agricultural Experiment Station

Leafhopper Burn, photo by David Handley

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 Pest Management Guide for sources of predatory mites.

Two-spotted Spider Mites, 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® or Kelthane® can be effective, but must be applied in 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.

Cyclamen Mite Damage, photo by David Handley

Weeds:  Weeds tend to become a big problem during the summer because they are often forgotten among all the other demands on our time and because of limited chemical 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.  Such applications have been of minimal benefit in northern New England, and sometimes result in injury to the strawberries.  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.

Visit the New England Small Fruit Pest Management Guide online for more detailed pest information at: www.umass.edu/fruitadvisor .

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.

A Member of the University of Maine System

For full page print version, please see link at the bottom.

Insect and Mite Pressure Moderate as Harvest Season Begins

Birds (Cedar Waxwings) Take a Bite Out of Early Ripening Fruit

Situation:  Picking has started in earnest in some fields that were under row covers this spring, so a few quarts are starting to show up at stands and farmers’ markets.  Pick-your-own fields will probably start opening next week with more to follow the week after.  Most fields will have a very early start, leading to concerns about fruit availability on the 4^th of July weekend, but other fields may only be a few days earlier than normal, depending on location and how well the fields escaped frost injury.   The Strawberry IPM Newsletter will take a couple of weeks off while we enjoy the harvest and will be back with our Renovation Issue at the end of June.

Strawberry bud weevil or “clipper”:   All fields scouted this week were well beyond the bud stage, when clipper poses a threat.  Keep in mind that these insects could still pose a threat to raspberries or blackberries that are still in the bud stage.

Tarnished plant bugs:  Over half of the fields scouted this week were over the recommended threshold for controlling tarnished plant bug, so sprays were recommended in fields not yet being harvested.  Once the fruit start to ripen, further controls should not be necessary.  When the young fruit start to swell, tarnished plant bug feeding is unlikely to cause significant injury.

Two-spotted spider mites:  Mites continue to be present in low numbers in most of the fields scouted.  However, none have reached the economic threshold of 25% of leaves sampled being infested with mites, so no controls have been recommended.  At this point, controls could be delayed until after bed renovations.

Gray mold:  So far, gray mold has not been showing up as a problem in fields where harvest is underway.  It appears that we may be in for a stretch of rain showers over the next week, so any fields still in bloom should be protected with fungicides as necessary.  Typically, we would recommend fungicide applications be spaced 7 to 14 days apart during the bloom period.  However, if more than one inch of rain has fallen since the last application, it is likely that protection is now inadequate, and a fungicide may need to be re-applied.

Gray Mold on Strawberries, photo by James Dill

Anthracnose fruit rot:  Keep an eye open for this potential problem in the coming days and weeks as fruit starts to ripen in fields that are wet from irrigation or rain. Anthracnose is favored by warm, humid conditions and can spread rapidly under rainy, wet conditions.  Anthracnose is identified by black sunken lesions with wet, orange (and sometimes gray) spore masses in them. The fungus is able to multiply on leaves without visible symptoms, which is why it may appear suddenly and widespread in a field.  Fungicides such as Cabrio® and Abound® can provide good control of anthracnose fruit rot.

Anthracnose on Strawberry, photo by North Caroline State University

Birds, specifically cedar waxwings have been seen feeding on ripe fruit in nearly every field we visited this week.  These birds can 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 caused by these birds.  Usually, they are discouraged when the fields start to be regularly harvested and lots of customers are present.  Songbirds such as cedar waxwings are protected by law and should not be killed. However, permits may be issued for killing birds by the U.S. Fish and Wildlife Service if they receive a recommendation for such a permit from the Maine Wildlife Services Office (part of the USDA Animal and Plant Health Inspection Service) in Augusta, along with an application from the grower.  There is a $50 fee for the application, and it may take over a month for the permit to be processed.  However, the permit is good for one year, so if you have problems this season, you may consider applying for a permit this winter.  This would allow you an option to kill birds, if necessary, next season.  The Wildlife Damage Office has recommendations for managing birds in crops, and also has some control options available through their office.  For more information on permits or bird control, contact the office in Augusta at 207.629.5181.  The office is located in the Capital West Business Center at 79 Leighton Road in Augusta.

Cedar Waxwing, photo by Cornell University

Bird Damage on Strawberry, photo by David Handley

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.

Strawberry Harvest, photo by David Handley

Reminder: Farm Tour and Calibration Clinic
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a growers meeting at Snell’s Family Farm in Buxton on Wednesday, June 16^th at 3:30 p.m. There will be a calibration demonstration for boom and air-blast sprayers, and a tour of John and Ramona Snell’s family vegetable and fruit operation, including high tunnels, greenhouse, market and storage facilities.  Snell’s Family Farm is located at 1000 River Road (Route 112) in Buxton.

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.

For full page print version, please see link at the bottom.

Early Harvest Getting Underway in Southern Maine

Tarnished Plant Bug Continues to be Active

Situation:  Fairly dry conditions are leading some growers to water fields to keep fruit sizing up well as harvest approaches. A few ripe berries are being picked in some fields in southern Maine that were under row covers, and non-covered early varieties are not far behind.  It looks like a very early harvest season ahead, leading to concern that some fields may have no fruit left for the 4^th of July, typically our big week.  There is still plenty of bloom in more northern fields, where scouting for tarnished plant bugs and mites should continue, as well as protection against gray mold.

Strawberry bud weevil or “clipper”:  Plants are generally well beyond the bud stage, when clipper poses a threat.  However, late blooming varieties in the northern part of the state where there are still primary and/or secondary flowers in bud stage should continue to be scouted for damage.

Reminder to Raspberry Growers:  Strawberry clipper will move onto raspberry buds when strawberry buds aren’t available.  Check raspberry flower clusters for clipped buds and live clippers.  Insecticide sprays to control raspberry fruit worm adults, which are also active at this time, should provide some control of clipper as well.  Products registered for clipper on raspberries include Brigade®, Sevin XLR Plus® and Aza-Direct®.

Tarnished plant bugs continue to be active this week. About one half of the fields we scouted were over the action threshold for tarnished plant bug nymphs, and sprays were recommended. Adult tarnished plant bugs are also still present, so more nymphs are likely to emerge in the coming days.  Nymphs are initially very small, about 1/16^th inch and light yellow-green.  As they grow, the color becomes more pale green and wing pads become visible on their backs.  They are usually feeding on the flowers and are very active, running quickly or falling to the ground when disturbed.

First Instar Tarnished Plant Bug Nymph, photo by David Handley

Two-spotted spider mites:  Populations of spider mites have been rising in some fields this week, as we should expect with hot, dry weather.  However, no fields have yet reached the economic threshold of 25% of leaves sampled being infested with mites, so no controls have been recommended.  Hopefully, we may be able to put off controls for mites until after harvest in fields where fruit is close to ripening.  The renovation process offers one of the best opportunities to get mites under control, through leaf mowing, improved spray penetration and a good environment for predator releases.

Two-spotted Spider Mites, photo by David Handley

Sap beetles may appear as we start harvesting berries.  These insects chew small holes in ripening fruit, similar to slug injury.  The beetles are about 1/8 inch long and dark brown in color.  They are usually found in the holes they’ve chewed into ripe fruit, but they 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 them thoroughly and regularly.  Insecticide sprays for this pest can be effective, but should be a last resort during the harvest period. Brigade®, Assail® 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.

Sap Beetle, photo by New York State Agricultural Experiment Station

Slugs may also start feeding on strawberries as they start to ripen. Moist conditions and mulch encourage the presence of slugs. These mollusks usually feed at night, leaving large holes and tunnels in ripening fruit and shiny slime trails on the leaves. Baits such as Deadline®  and Sluggo® offer some control of slugs, but should be used prior to fruit ripening, and avoid contacting the developing fruit with the bait.  Pay close attention to label instructions and precautions. Slugs overwinter in the egg stage; so baits should also be applied to the fields in mid-September, if slugs have been a problem, to reduce egg-laying.

Slug on Strawberry, photo by James Dill

Strawberry rootworm adults and feeding injury have been found on strawberry leaves in a field last week.  The adult stage of this insect is a small (1/8”) dark brown beetle.  The beetles feed on strawberry leaves during the spring and again during the late summer, causing numerous small holes in the leaves.  The larvae are small grubs that feed on the roots of strawberry plants, causing them to be stunted and weak.  These are not to be confused with strawberry root weevil, a larger insect and more serious pest. Control is not recommended prior to harvest for the early generation of adults.  However, if strawberry rootworm beetles and/or feeding are noted in a field after renovation, a treatment is recommended.  Sevin® is registered for control of this pest.

Strawberry Rootworm Beetle, photo by James Dill

Gray mold:  Management of Botrytis should be finishing up in southern Maine as fields move into the later stages of fruit development and ripening.   More northern growers who still have fields in bloom should continue to protect the blossoms with fungicides, especially if any wet weather occurs during the bloom- to post-bloom period.

Gray Mold on Strawberries, photo by James Dill

Powdery mildew:  The warm, dry weather has increased the number of fields showing symptoms of powdery mildew during the past week. “Cupping” or upward curling of the leaves has been prevalent in several fields in southern Maine.  Several fungicides that are applied during the bloom period for gray mold will also offer good protection against powdery mildew, including Pristine®, Captan plus Topsin-M® and Stylet oil.  Other products offer control of powdery mildew but are not considered effective for gray mold, including Procure®, Rally® Quintec® and Cabrio®.

Powdery Mildew, photo by David Handley

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° Fahrenheit 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° 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.

Reminder:  Farm Tour and Calibration Clinic
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a growers meeting at Snell’s Family Farm in Buxton on Wednesday, June 16^th at 3:30 p.m. There will be a calibration demonstration for boom and air-blast sprayers, and a tour of John and Ramona Snell’s family vegetable and fruit operation, including high tunnels, greenhouse, market and storage facilities.  Snell’s Family Farm is located at 1000 River Road (Route 112) in Buxton.

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.

For full page print version, please see link at the bottom.

Frost Injury Variable Around the State

Tarnished Plant Bug Threatens Some Fields; Spider Mites Getting Active

Situation:  Strawberry fields around the state are mostly in mid-late bloom, although rumor has it that a few red fruit were picked from beds in southern Maine that were under row covers.  Fields in northern Maine are now in early bloom. Blossom damage from last week’s freeze and frost is still quite visible, and with later flower buds now opening, the damage does not look as severe in some fields as it did last week.  However, we still have 1-2 weeks of potential frosty nights to surmount, so remain alert and ready to water. Reminder: Growers with NAP insurance should call in/report even possible cold/frost damage losses to FSA within 7-10 days of occurrence to qualify.

Frost Injury, photo by David Handley

Strawberry bud weevil or “clipper”:  Most fields in southern Maine are beyond the growth stage (blossoms in bud stage) where clipper poses a threat.  Once beds are in full bloom, clipper will not cause economic harm. For fields still in early bloom, we have found clipper damage on remaining buds, so this pest is becoming more active, and fields not yet in full bloom should continue to be scouted.

Clipper Beetle on Strawberry Bud, photo by James Dill

Clipper Injury, Photo by David Handley

Tarnished plant bugs were very active this week. Most fields in bloom that we scouted were over the action threshold for tarnished plant bug nymphs, and sprays were recommended. Adult tarnished plant bugs are still feeding on blossoms, and presumably laying eggs.  Products registered for controlling tarnished plant bug include Brigade®, Danitol®, Malathion®, Thionex® and PyGanic®.  Keep in mind that bees and other pollinators are also very active in your fields now, so apply pesticides at night when they are less active and use materials that pose the least threat to pollinators.  See page 115 of the 2010-2011 New England Small Fruit Pest Management Guide for more information.  Don’t have a copy?  Give us a call or drop us a line.

First Instar Tarnished Plant Bug Nymph, photo by David Handley

Tarnished Plant Bug Injury, photo by David Handley

Two-spotted spider mites: While populations continue to be very low in all fields we’ve scouted, we are starting to see mites and their eggs showing up on the undersides of leaves.  No controls were required yet, but dry, warmer weather will allow populations to builds up quickly, so we should expect that we may see some fields getting near threshold in the next week or two.

Spittlebugs: We found our first spittlebugs of the season in strawberry beds this week. The frothy spittle masses are typically found on the leaf stems (petioles), just below the leaflets. These typically start showing up around bloom. Although these insects don’t pose a significant threat to the plants, the frothy spittle they cover themselves with creates an annoyance for pickers.  Adult spittlebugs are about ¼ inch long and bright green when they first emerge but later turn dull yellow or brown.  Spittlebugs overwinter as eggs and the nymphs emerge in late May.    You should start to scout for spittlebugs when the plants are at about 10% bloom.  Randomly inspect five one square foot areas per field every week.  On hot, dry days 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 the white, frothy spittle masses.  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®.

Spittlebug, photo by David Handley

Gray mold:  With plants in bloom, now is the time to protect against gray mold. Most growers have applied at least one fungicide spray at this point, and many have applied a second, as strawberries reach the mid- to late-bloom stage.  Frost injury to blossoms will create dead plant tissue, which will further encourage the Botrytis fungus, so every precaution is needed this spring to protect flowers and fruit from infection.

Powdery mildew: Upward curling of the leaves has been a more common sight in strawberry fields this week, indicating that powdery mildew is starting to become more prevalent.  In addition to leaf curling, purple or red blotches on the leaf petioles and white, powdery growth may be observed on the undersides of the leaves.  Check your fields for symptoms now.  You’ll probably notice differences in varieties, as some are more susceptible to powdery mildew than others. Abound®, Captan, Pristine®, Cabrio®, Topsin-M® and Stylet oil are presently registered to control powdery mildew.

Powdery Mildew, photo by David Handley

Leaf spot infections are also starting to appear in some fields this week.  Leaf spot usually appears on older leaves, as small purple or red spots with white centers.  Under heavy infections, a number of spots may coalesce and give the leaf a burned appearance.  Leaf scorch is another foliar disease with a similar diagnosis.  The spots on the leaves tend to be smaller in the case of scorch, and lack the white centers.  Many spots may coalesce to turn the leaves purple and necrotic,   leading to the death of the leaf and weakening of the plant.  Strawberry varieties vary greatly in their susceptibility to leaf spot and leaf scorch, with many having at least some resistance.  However, under high disease pressure, many will show some symptoms.  Fungicides registered for leaf spots include Captan, Topsin-M®, Syllit®, Cabrio®, Nova® and Pristine®.  Bear in mind that many strawberry leaves were injured by the freeze event on the 10^th of May and have a burned appearance now as a result.  Leaves infested with leaf spot or scorch will typically have purple discoloration surrounding the dead area.

Leaf Spot, photo by David Handley

Leaf Scorch, photo by David Handley

Anthracnose fruit rot is a potential problem for growers in the coming weeks as fruit starts to ripen in fields that may still be wet from irrigation or rain. This fungus is favored by warm, humid conditions and can spread rapidly during rains or frequent irrigation.  In cool seasons, it tends to appear close to harvest or may not show up at all.  Anthracnose fruit rot can be identified by black sunken lesions with wet, orange (and sometimes gray) spore masses in them. The anthracnose fungus is able to multiply on the leaves without visible symptoms, which may explain its sometimes widespread and sudden appearance in fields.  Fungicides such as Cabrio® and Abound® can provide good control of anthracnose fruit rot.

Reminder: Farm Tour and Calibration Clinic
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a growers meeting at Snell’s Family Farm in Buxton on Wednesday, June 16^th at 3:30 p.m. There will be a calibration demonstration for boom and air-blast sprayers, and a tour of John and Ramona Snell’s family vegetable and fruit operation, including high tunnels, greenhouse, market and storage facilities.  Snell’s Family Farm is located at 1000 River Road (Route 112) in Buxton.

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.

For full page print version, please see link at the bottom.

Growers Battle Frost Injury to Strawberry Flowers

Early Bloom Subjected to Record Low Temperatures

Situation:  Most strawberry fields around the state are in early to mid bloom, although beds that were under row covers are at petal fall to green fruit.  Fields in northern Maine or those where mulch was removed late should be coming into bloom next week.  Record low temperatures on Tuesday (5/11) night brought a freeze to strawberry fields, which were flowering well ahead of normal due to earlier warm temperatures.  This was followed by two more nights of frost on most fields, resulting in varying degrees of frost injury on blossoms around the state. Damage appears to range from near 80% of flowers killed to less than 10%, depending on field location and the grower’s ability to protect the flowers with irrigation.  I have been quite impressed with how well most have been able to protect the crop.  However, it is not over yet.  We still have 2-3 weeks of potential frosty nights to surmount, so remain alert and ready to water.

Frost Injury to Flowers and Leaves, Photo By David Handley

 Strawberry bud weevil or “clipper” has been more active this week, although overall activity is still relatively low.  I have seen more bud damage and a few live weevils, especially in older beds, with two fields being over threshold. Clippers are likely to become more active over the next week as flower buds increase and temperatures warm. Scout for clipped buds in any plantings from bud to early bloom.  If more than one bud on average is clipped for every two feet of row length, control measures are recommended.  Damage is usually first noticed at the edges of the field.

Tarnished plant bugs are also becoming more active this week.  My sanity was questioned more than once by passersby who saw me crawling about strawberry fields “beating the heck” out of plants with a paper plate, but my efforts paid off as I found first instar tarnished plant bug nymphs in two fields in southern Maine.    I also continue to see adult tarnished plant bugs feeding on blossoms, and presumably laying eggs.  I suspect we will be seeing more nymphs in the coming days, especially if the weather gets warmer and remains dry. Plant bug nymphs are small, active, yellow-green insects. You can scout for them by tapping flower clusters over a plate.  If four or more flower clusters out of 30 have any nymphs, control measures should be taken.

Tarnished Plant Bug Injury, Photo by David Handley

Cyclamen mites:  Most of the fields I have visited this week have some evidence of cyclamen mite injury. Symptoms include weak growth and yellow, pinkish or blackened, crinkled leaves.  These mites are very small, smaller than spider mites, and feed on the developing leaves and flower buds well within the crown.  Thionex® or Kelthane® applied with lots of water to get the material down into the crowns can provide control of these mites.

Cyclamen Mite Damage, Photo by David Handley

 Gray mold:  Most growers have applied their first bloom spray of fungicide to protect strawberry flowers from infection by gray mold.  The gray mold fungus is most problematic during bloom, and the recent nights of irrigation to prevent frost damage have created a great environment for this disease to spread.   Make sure you keep the blossoms protected with fungicides during bloom.  Typically 2-3 applications will be necessary during this time.  See last week’s issue of this letter for a list of fungicides.

Bacterial angular leaf spot: I have found plants with symptoms of angular leaf spot (Xanthomonas fragariae) in one field this week.  Angular leaf spot is a bacterial disease characterized by small, translucent or “water-soaked” leaf spots that occur between the veins. The spots coalesce, turning yellow, reddish and eventually black.  The symptoms tend to start on the lower leaves and move up as bacterial spores are splashed by rain or irrigation water. Infection of the calyxes may also occur, resulting in blackened berry stems and caps.  Irrigation for frost protection encourages the development of this disease. Copper-containing chemicals, such as Kocide, Cuprofix, and Bordeaux are the only materials that have some effect on this disease.  Some labels suggest adding lime as a “safener” to reduce the risk of crop injury. Spray applications should begin before bloom to prevent spread of bacteria on the leaves before they spread to berry caps. Application of copper sprays after bloom can result in fruit injury and is not recommended.  Recent research suggests that hydrogen dioxide (OxiDate®) may also have some activity against angular leaf spot when used on strawberries as part of a gray mold management program.

Bacterial Angular Leaf Spot, Photo by David Handley

 Leather rot (Phytopthora cactorum) could become an issue with a lot of water standing in the fields from frost protection. Foliar sprays of Aliette®, Agri-Phos® or Phostrol® (similar to Aliette®) should provide control. Spray during bloom and fruit development.

2010-2011 New England Small Fruit Pest Management Guide is Here!
The 2010-2011 New England Small Fruit Pest Management Guide has recently arrived from the printers and is now available to Maine growers.  The Guide is available through the University of Maine Cooperative Extension and can be ordered from the Highmoor Farm office.  The cost is $10.00 per copy, including tax and shipping. Checks should be made out to “UMaine Cooperative Extension” and sent to Highmoor Farm, attn: Pam St. Peter, P.O. Box 179, Monmouth, ME 04259.

Reminder: Farm Tour and Calibration Clinic
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a growers meeting at Snell’s Family Farm in Buxton on Wednesday, June 16^th at 3:30 p.m. There will be a calibration demonstration for boom and air-blast sprayers, and a tour of John and Romana Snell’s family vegetable and fruit operation, including high tunnels, greenhouse, market and storage facilities.  Snell’s Family Farm is located at 1000 River Road (Route 112) in Buxton.

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.

For full page print version, please see link at the bottom.

2010 Strawberry Pest Management Season Begins

Warm Weather Has Strawberry Crop Well Ahead of Schedule

Strawberry plants around the state are getting off to a very early start this spring, as a lack of snow cover and very warm temperatures have pushed plants into bloom two to three weeks early.  We will start scouting strawberry fields for major insect pests in earnest next week, including volunteer farms in North Berwick, Wells, Cape Elizabeth, Poland Spring, New Gloucester, Dresden, Monmouth, Wayne, and Farmington, and will be reporting our findings through this newsletter on a weekly basis until harvest time.  If you would prefer to receive this message via e-mail, please give us a call at 933.2100 or send an e-mail message to: david.handley@maine.edu.

The best way to manage strawberry pests is to scout your own fields regularly and often. Start now, if you haven’t already. You should be able to identify the major pests and their damage, and be able to determine if control measures are necessary.  To properly scout your fields you may want a copy of the Strawberry Production Guide for the Northeast, Midwest and Eastern Canada. This contains detailed information on strawberry pest identification and monitoring, and also provides information on all other aspects of strawberry production.  It may be purchased for $45.00 per copy from the University of Maine Cooperative Extension. You can order it online at: http://extensionpubs.umext. maine.edu/.  You should also have a copy of the 2010-2011 New England Small Fruit Pest Management Guide, which contains the latest information on management control options for the major strawberry pests as well as scouting information.  Color pictures of the important strawberry pests are now also printed in the 2010-2011 New England Vegetable Management Guide. An order form for these guides is included with this newsletter.

Situation:  Fields that were under row covers are beyond full bloom in southern Maine, while mulched fields are mostly in early bloom.  Poor snow cover and an inability to get adequate mulch on plants last fall has led to winter injury in some fields, but for the most part this appears to be moderate. Early bud emergence has also led to some frost injury on opening flowers, but this damage has also been fairly light.  Frost control is now a high priority for growers, as we are in bloom in much of the state with two to three weeks of frost danger remaining.  Be ready to irrigate for frost control as soon as flower buds are visible.  Bear in mind that if fields need to be irrigated for frost repeatedly in the coming weeks we will increase the risk of bacterial angular leaf spot becoming a problem.

  bacterial angular leaf spot

Strawberry bud weevil or “clipper” is becoming active in strawberry fields as more flower buds emerge. I have found signs of adult feeding activity (holes in flower petals), as well as bud clipping in early varieties this week.  Expect these insects to be active in the coming days as more flower buds become available. The clipper is a small weevil, which girdles strawberry flower buds, causing them to dry up and fall off the flower stalk.  Scout for damage by counting the number of clipped buds in two feet of row length at five different locations in a field.  If the average number of clipped buds per two-foot sample exceeds 1.2, or if live clippers are found, control measures are recommended.  Damage is usually first noticed at the edges of the field.  Border sprays may be effective in keeping this insect from becoming a problem in larger fields.  Fields with a history of clipper problems will typically exceed threshold nearly every year.  Insecticide options for clipper include Lorsban®, Brigade®, Sevin® and PyGanic®.

 feeding signs of strawberry clipper – holes in petals

 clipped flower buds from strawberry clipper

Tarnished plant bugs are also active this week.  We have seen adults in the fields feeding on blossoms, and presumably laying eggs.  This suggests that nymphs should begin to appear in one to two weeks.  The nymphs are small, active, yellow-green insects. It is important to scout for the nymphs regularly, as they can show up quickly in warm weather. Tarnished plant bugs feed on the open strawberry flowers, causing the berries to have seedy ends.  To scout for this insect shake 30 flower clusters (six clusters in five different locations) over a plate.  If four or more of the clusters out of the 30 sampled have any nymphs, control measures should be taken. Be on the alert and scout your fields now!  Insecticide options for tarnished plant bug include malathion, Brigade®, Danitol®, Thionex® and PyGanic®.

 tarnished plant bug adult

Cyclamen mites:  Plants showing weak growth and yellow, pinkish or blackened, crinkled leaves may be infested with cyclamen mite.  Cyclamen mites are very small, smaller than spider mites, and reside in the crown of the strawberry plant feeding on the developing leaves and flower buds.  They are very hard to see, even with magnification.  Infested plants have shrunken distorted leaves and flower stalks, and produce few, if any, marketable fruit.  Miticides such as Thionex® or Kelthane® 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.  I have found cyclamen mites in several fields this week, so be on the look out for these symptoms.

 cyclamen mite damage on strawberry plant – small, crinkled leaves

Two-spotted spider mites have not yet been a problem this spring, but growers with plants under rowcovers should be alert.  This is often where we first find mite problems.   Spider mites will reproduce rapidly when warmer weather arrives, so it is important to scout for them regularly.  Spider mites feed on the undersides of strawberry leaves, rasping the plant tissue and sucking the sap.  Infested leaves will develop yellow flecking and a bronzed appearance.  The plants become weakened and stunted.  Fields that have had excessive nitrogen fertilizer and/or rowcovers tend to be most susceptible to mite injury. To scout for mites, collect 60 leaves from various locations in the field, and examine the undersides for the presence of mites.  Mites are very small – you may need a hand lens to see them. Chemical control options for two-spotted spider mites include Acramite®, Savey®, Zeal®, Vende®x, 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).

Root weevil management
We have observed some grubs of strawberry root weevil this week.  Infested plants appear weak and stunted, usually in somewhat circular patches in a field.  Digging under the plants will reveal small (1/4 -1/2”) crescent-shaped legless grubs.  Typically, the grubs begin to pupate when the plants are in bloom, but we have seen both small grubs and pupae already this spring.

A soil drench of Platinum® (thiamethoxam) insecticide during the spring and/or fall when the grubs are active in the soil can provide control. However, Platinum® has a 50 day pre-harvest interval, so it is too late for applications in most fruiting fields this year.  Platinum® may also be used as a pre-plant or planting treatment for root weevils.  We’ll provide more information on root weevils in a future issue.

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

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

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

Leather rot (Phytopthora cactorum) may also become an issue this season if you have a lot of water in the fields during bloom and fruit development, especially if you did not get mulch on the fields last fall and the plants are on bare wet soil.  This disease is best controlled by growing strawberries in well-drained soil and by applying straw mulch between the rows to prevent the berries from touching the soil and preventing soil from splashing up onto the berries. Foliar sprays of Aliette®, Agri-Phos® or Phostrol® (similar to Aliette) may also provide control.  Spray during bloom and fruit development.

Red stele root rot
With the rapid warm up of and drying of the soils this spring, I do not expect red stele root rot to be a major problem, but it is not too late to be checking fields for symptoms if fields appear to be weak, stunted or dying.  To diagnose red stele, pull up a few plants that look weak and scrape the roots of these plants to see if the center of the root, known as the stele, is a rusty red in color, instead of the normal white.  The red color would indicate an infection. Red stele is caused by Phytophthora fragariae, a soil pathogen that infects roots when soils are wet with temperatures are around 50°.  The pathogen grows into the roots causing the plants to become weak, stunted and eventually die.  Symptoms are most evident in the spring, and can be mistaken for winter injury. Ridomil Gold®, Aliette® or Phostrol® are fungicides that can be applied in the late fall or early spring for control of red stele.  Many varieties have some level of resistance to the disease, but the most effective management strategy is to plant only into well-drained soils, and/or plant onto raised beds.

Powdery mildew: This fungus disease has been starting to show up as purple or red blotches on the leaf petioles and flower stems in some fields.  Most of us are more familiar with the later symptoms of  upward curling of the leaves and white, powdery growth on the undersides of the leaves.  Check your fields for pinkish purple leaf and flower stem lesion symptoms now. Abound®, captan, Pristine®, Cabrio®, Topsin-M® and JMS Stylet Oil® are presently registered to control powdery mildew.

Farm Tour and Sprayer Calibration Clinic
The University of Maine Cooperative Extension and the Maine Vegetable and Small Fruit Growers Association will hold a growers meeting at Snell’s Family Farm in Buxton on Wednesday, June 16^th at 3:30 p.m. Dr. Rich Bonanno, Vegetable Specialist with the University of Massachusetts will demonstrate practical calibration techniques for both boom and air-blast sprayers.  We will also tour John and Ramona Snell’s family vegetable and fruit operation, including high tunnels, greenhouse, market and storage facilities.  Snell’s Family Farm is located at 1000 River Road (Route 112) in Buxton.

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.

2010-2011 New England Small Fruit Pest Management Guide is Here!

The 2010-2011 New England Small Fruit Pest Management Guide has recently arrived from the printers and is now available to Maine growers.  The Guide has been expanded once again, and contains all the up-to-date pest management and cultural management recommendations for berry crops.  It includes many handy reference charts for pesticide and fertilizer use.   Because of significant changes in pesticide registrations, it is recommended that any earlier editions of the Guide be discarded.  The Guide is available through the University of Maine Cooperative Extension and can be ordered from the Highmoor Farm office.  The cost is $10.00 per copy, including tax and shipping.  Checks should be made out to “UMaine Cooperative Extension” and sent to Highmoor Farm, attn: Pam St. Peter, P.O. Box 179, Monmouth, ME 04259.    The 2010-2011 New England Vegetable Management Guide is also available now and includes color pictures of common strawberry insects and disease problems.  The cost of both of these publications has been reduced for growers, thanks in part to grants from the USDA’s Risk Management Crop Insurance Program.

———————————————————————————————-

Order Form

Please send me the following Guide(s) (check all that apply):

2010-2011 New England Vegetable Management Guide ($25.70) 

_______

2010-2011 New England Small Fruit Pest Management Guide ($10.00) 

_______

Prices include sales tax and shipping.

Checks should be made payable to: UMaine Cooperative Extension

Name:              _______________________________________

Farm Name:     _______________________________________

Address:          _______________________________________

_______________________________________

Zip Code:         ____________

Telephone:       _______________________________________

E-mail:              _______________________________________

Please return this form with payment enclosed to:

UMaine Cooperative Extension
Highmoor Farm
P.O. Box 179
Monmouth, ME  04259
Attn. Pam St. Peter.