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Strawberry IPM Newsletter No. 6 – June 14, 2013

Strawberry IPM Newsletter No. 6 – June 14, 2013

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


Wet, Cool Weather Slows Ripening, Elevates Fruit Rot Threat

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

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

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

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

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


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

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

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


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

√      Signs to the farm are neat and easy to read.

√      There is easy access to the fields and plenty of parking.

√      Someone is ready to greet customers and offer parking instructions and directions to the field.

√      Access to the field is free of hazards.

√      Transportation is provided for the elderly and disabled.

√      The rules regarding picking are clearly posted.

√      Someone is in the field to show customers where to pick and to answer questions.

√      There are plenty of picking containers available.

√      Clean restroom and hand washing facilities are available.

√      Someone is available to help customers carry fruit out of the field.

√      The checkouts are fast and efficient.

√      Beverages are available.

√      Shade and seats are available for customers wanting to rest.

√      The help are friendly and knowledgeable.

A friendly, clean, and organized atmosphere will leave a lasting impression on your customers, encouraging them to come back and to recommend your farm to their friends.

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


David T. Handley
Vegetable & Small Fruit Specialist

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

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

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

Image Description: Print Friendly

Image Description: Strawberries

Image Description: Gray Mold on Strawberries

Image Description: Large Tarnished Plant Bug Nymph

Image Description: Spittlebug

Image Description: Male and Female Spotted Wing Drosophila Flies

Image Description: Girl with Quarts of Strawberries


University of Maine Cooperative Extension

Contact Information

Cooperative Extension at Highmoor Farm
52 U.S. Route 202
Monmouth, Maine 04259-0179
Phone: 207.933.2100
The University of Maine
Orono, Maine 04469
A Member of the University of Maine System