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Strawberry IPM Newsletter No. 5 – June 15, 2012

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


Leaf Spot, Gray Mold, Powdery Mildew Evident

Situation:  Most southern fields will open in earnest this week, and it appears that we’ll have a stretch of nice weather for it (at last).  The crop size and quality looks fair to good in most fields.  The open winter, spring frosts and prolonged rains have all taken their toll; such that many fields look good but lack “depth” as one grower I talked with recently put it, meaning that the season could be fairly short this year, especially for fancy quality fruit.  The predicted warm weather next week will also hasten ripening, so if you haven’t started advertising yet, don’t wait.  Most fields are past the point where clipper or tarnished plant bug could cause injury, and scouting should focus on pests that attack ripe fruit, such as sap beetles, slugs, birds, and anthracnose fruit rot.  The Strawberry IPM Newsletter will take a couple of weeks off while we enjoy the harvest and will be back with our Renovation Issue in July.

Tarnished plant bugs were very scarce this week.  We saw only a few adults in the fields, and no nymphs.  A combination of timely sprays and wet weather appears to have kept these insects from being a problem in the fields we have visited this spring.  Keep scouting if you have late fields that are still in bloom.

Two-spotted spider mites are being found in most strawberry fields we scouted this week, although they have been below spray threshold levels; and we have also seen predatory mites in these fields.  With a predicted warm dry stretch of weather ahead, populations could increase fairly dramatically, especially if you have recently applied a broad spectrum pyrethroid insecticide such as Brigade©, which is very toxic to predatory mite species that can slow spider mite outbreaks.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by Michigan State University

Diseases:  Walking through fields with ripe fruit this week, the most common problem observed was gray mold.  This was not unexpected, given the amount of rain we’ve had, and the levels of rot were generally low.  If you have fields that are not yet ready to pick, and more than one inch of rain has fallen since your last application of fungicide, you should consider another spray.

Gray Mold on Strawberries

Gray Mold on Strawberries, photo by James Dill

Leather rot (Phytopthora cactorum) has been found in one field this week.  Reports of dull-colored fruit with bitter flavor may indicate the presence of leather rot.  The fruit is also tough and may have a pink or purplish tinge.  Foliar sprays of Aliette©, Agri-Phos© or Phostrol© can provide control of this disease.

Anthracnose fruit rot has been reported in southern New England this week.  This is usually a problem when fields have standing water present and warm temperatures.  The fruit show sunken patches of brown or black.  Whole fruit may suddenly turn soft or dry up to blackened mummies.  I haven’t seen anthracnose in the fields that I have visited so far, but be aware that this could still become a problem.  Effective fungicides include Cabrio© and Abound©.

Powdery mildew:  Mild symptoms of powdery mildew can be seen in most fields with susceptible varieties.  Again this is due to the poor weather this spring.  Discoloration of the fruit stems and caps may occur, in addition to the commonly seen leaf cupping.  Fungicides registered for control include: Abound©, captan, Pristine©, Cabrio© and Topsin-M©.

Leaf spot infections are becoming more noticeable as harvest gets underway, especially in plantings of ‘Wendy’.  Severely infected plantings look weak, have poor fruit size and reddened or brown stems and caps.  Fungicides registered for leaf spots include captan, Topsin-M©, Syllit©, Cabrio©, Nova© and Pristine©.

Leaf Spot on Strawberry Plant

Leaf Spot, 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 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.

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

Strawberry Harvest, photo by David Handley

Websites worth visiting
If you are looking for information to help diagnose a problem in your strawberries or need a recommendation for a control strategy, the New England Small Fruit Pest Management Guide is available on-line.  You should also check out Cornell University’s Berry Diagnostic Tool.


David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                                  Pest Management
P.O. Box179                                      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.



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