Cooperative Extension at Highmoor Farm

Spotted Wing Drosophila Alert and Berry Notes — August 2, 2024

David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist, Phil Fanning, Assistant Professor of Agricultural Entomology, Christina Howard, Maine New Farmer Project Manager

Spotted Wing Drosophila:

Fly counts in our vinegar/yeast traps were similar to last week’s numbers and were high enough in nearly all locations to warrant protective sprays to ripening berry and soft fruit crops to protect against infestation. I found larvae feeding in raspberries and blueberries this week at several locations. The presence of any larvae in ripening fruit should initiate a regular spray program to prevent further infestation. When 6 to 10 flies are caught in a yeast-baited trap in a week, larvae will start appearing in the fruit. This week counts ranged from 0 to 266 in our traps, indicating that that ripening fruit needs protection to prevent infestation.

Expect SWD populations to increase as more food becomes available. In addition to setting up traps, look for fruit flies hovering around fruit and symptoms of premature fruit decay. A 7-day spray interval should be adequate to minimize fruit infestation, but as populations continue to build, a shorter interval may be required.

For more information on identifying spotted wing drosophila (SWD) and updates on populations around the state, visit our SWD blog.

Berry Notes:

• Blueberry harvest in southern Maine is in full swing and some farms are winding down early, as the hot weather has condensed the harvest season. Growers should continue to keep an eye out for Anthracnose fruit rot. The weather has been very conducive for this fungus. Infected berries soften and collapse. Small orange dots will develop on the fruit surface, which are the spores.
• Potato leafhoppers continue to cause damage on strawberries and raspberries. Leaves and new shoots can look twisted and streaked with yellow, and may turn necrotic. Look for the small, bright green nymphs on the undersides of the leaves.
• Strawberry growers should monitor their fields for spider mites and cyclamen mites through the summer.
• Strawberry fields that had problems with root weevils should apply controls for the adults soon. Foliar sprays of Brigade® applied in the evening are recommended for the weevils, which are now laying eggs. Drench applications targeting the grubs should be applied in the late summer or early fall.

Other IPM Web Pages
Michigan State University Spotted Wing Drosophila
Penn State University Spotted Wing Drosophila Overview
University of New Hampshire SWD Weekly IPM Reports

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm
P.O. Box 179
Monmouth, ME 04259
207.933.2100

UMaine Extension Diagnostic Research Lab
Pest Management Unit
17 Godfrey Drive
Orono, ME 04473
1.800.287.0279

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

In complying with the letter and spirit of applicable laws and pursuing its own goals of diversity, the University of Maine System does not discriminate on the grounds of race, color, religion, sex, sexual orientation, transgender status, gender, gender identity or expression, ethnicity, national origin, citizenship status, familial status, ancestry, age, disability physical or mental, genetic information, or veterans or military status in employment, education, and all other programs and activities. The University provides reasonable accommodations to qualified individuals with disabilities upon request. The following person has been designated to handle inquiries regarding non-discrimination policies: Director of Equal Opportunity, 5713 Chadbourne Hall, Room 412, University of Maine, Orono, ME 04469-5713, 207.581.1226, TTY 711 (Maine Relay System).