Cooperative Extension: Maine Wild Blueberries

Insects - 209-Insect Control Guide for Wild Blueberries

Fact Sheet No. 209, UMaine Extension No. 2001 (209 PDF)

Prepared by David E. Yarborough, Extension Blueberry Specialist, Frank Drummond, Professor of Insect Ecology, School of Biology and Ecology, and Judith A. Collins, School of Biology and Ecology. The University of Maine, Orono, ME 04469.  Revised February 2013.

Blueberry Spanworm

Begin to monitor for spanworm larvae in early spring as the buds break and plants emerge by sweeping with a 12-inch diameter sweep net.  Spray with an insecticide or biocontrol when larval counts on fruit-bearing plants average over 10 per 10 sweeps.  The action threshold should be lowered to 3 or more larvae per 10 sweeps on vegetative year fields.  Repeat treatment if necessary.  More information may be found in the Wild Blueberry Fact Sheet No. 197 (UMaine Extension No. 2371), Blueberry Spanworm.

Blueberry Flea Beetle

An action threshold of 50 insects per 10 sweeps has been established for either larvae or adults. Examine fields in early spring for larvae and from mid-June to early July for foliar feeding by adults.  Spray with an insecticide or biocontrol as needed.  More information can be found in Wild Blueberry Fact Sheet No. 200 (UMaine Extension No. 2372), Blueberry Flea Beetle.

Thrips

When leaf curling occurs in a fruit bearing year, stake out infested area.  Consider pruning as a control; see the cultural techniques section.  The following spring, apply insecticide to the staked area before curling reoccurs.  Make first application when leaves are 1/4 inch to 1/2 inch long.  Repeat when 1/2 inch to 1 inch. These timings are critical. Yellow sticky cards may be used to monitor for blueberry thrips for more efficient timing of applications.  Refer to Wild Blueberry Fact Sheet No. 204 (UMaine Extension No. 2275), Integrated Crop Management Field Scouting: Guide for Lowbush Blueberries and Wild Blueberry Fact Sheet No. 202 (UMaine Extension No. 2373), Blueberry Thrips.

Blueberry Maggot

Monitoring for the presence of the blueberry fruit fly will indicate necessity for control based on trap capture threshold and, if needed, to ensure proper timing of insecticide applications. Cooperative Extension Fact Sheet No. 201 (UMaine Extension No. 5030), Monitoring for the Blueberry Maggot, outlines ways to monitor fields for the blueberry fruit fly and discusses perimeter treatments that greatly reduce the portion of the field that needs to be treated.

Never apply insecticides when less than three to five percent of berries have ripened and turned blue.  This is usually early July in most regions of Maine.  Repeat applications, if necessary, depending on trap capture results.

Spotted-Wing Drosophila

The Spotted-Wing Drosophila (SWD) is an invasive non-native small vinegar fly with the potential to cause considerable fruit loss of wild blueberries especially at the end of the harvest season.  It was first detected in Maine in 2011. Unlike most other vinegar flies that require damaged fruit to attack, SWD causes damage when the female flies cut a slit and lay eggs in healthy fruit. Monitoring for the presence of the SWD requires a different trap, placement and timing than our native blueberry maggot fly. See Extension Fact Sheet: Spotted-Wing Drosophila Traps at http://umaine.edu/blueberries/factsheets/insects/spotted-wing-drosophila-traps/

Apply insecticides at first capture usually in mid-August in most regions of Maine.  Repeat applications, if necessary, depending on trap capture results.  In order to prevent development of resistance rotate different classes (see recommendation table for insecticide class).

All publications may be found on the web at http://extension.umaine.edu/blueberries/factsheets/

Follow ALL label directions.

• Accurate identification of pests and monitoring to determine the best times to spray are critical for achieving effective, economical control.
• Apply pesticides only when economic thresholds are exceeded, based on monitoring.
• Use caution while loading spraying equipment with pesticides.  Follow all safety precautions.
• Use common sense when applying pesticides. DO NOT contaminate nearby lands, buildings, water bodies and roadsides. Keep domestic animals and children away from fields.
• For detailed information on safe spray use, please refer to the Wild Blueberry Growers Guide.
• Avoid aerial application of pesticides near buildings, public roads or water supplies or on windy days.
• Reentry restrictions: never enter a sprayed area without protective clothing or until stated on label.
• Be sure your sprayer is well cleaned and does not have any fungicide residue when using Botanigard since fungicide will kill the living spores.

Protecting Honey Bees from Insecticides

• All pesticides are not equally hazardous to bees.  Select the one that is least hazardous. Commonly used insecticides are listed in the chart according to their relative hazards.
• Do not apply insecticides near honey bee hives.
• Treat plants before (check persistence for each insecticide, for instance Phosmet is 7-10 day persistence) or after bloom, at night with low persistence insecticides, or when bees are not actively foraging in crop and pruned fields.

Information in this publication is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.

©2013

Published and distributed in furtherance of 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.

Call 800-287-0274 or TDD 800-287-8957 (in Maine), or 207-581-3188, for information on publications and program offerings from University of Maine Cooperative Extension, or visit extension.umaine.edu.

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