Nip clippers in the bud to keep berry blossoms

The strawberry is a fantastic fruit – it looks good, tastes good and is good for you. Strawberries contain vitamin C, iron, and ellagic acid, an antioxidant that inhibits cancer. To raise this healthful tasty treat, Maine growers must battle certain insect pests. Foremost among these is the strawberry bud weevil, better known as “the clipper” for its habit of clipping strawberry blossoms before they can develop into fruit.

Clippers are very small (a 10th of an inch) and seldom seen, but they can wreak havoc on strawberries. Untreated plantings may suffer 10 percent to 50 percent damage; total crop loss is possible. This pest is not found in every strawberry planting, but a field with a history of clipper can expect problems every year.

Adult clippers spend the winter in plant debris along fence rows, in wooded areas and under mulch in strawberry plantings. They emerge in spring when temperatures reach 60 degrees F. With no food for several months, their first craving is a meal of flower pollen, so a convenient strawberry field is just about heaven. They’re also attracted to blackberry, raspberry and cinquefoil blossoms. Clippers puncture unopened flower buds with their long snouts, cutting through the folded petals to feed on the immature pollen at the center. When these flowers open, small holes in the petals show where a clipper has been feeding.

After feeding, the adults mate and females begin laying eggs. They bite into unopened flower buds, deposit a single egg inside, and then girdle, or clip, the stem just below the bud to prevent it from opening. The clipped bud hangs from its stem or falls to the ground. The beetle grub develops inside the bud, and emerges after a month as a new adult. The new generation adults feed on flower pollen for a short time before seeking shelter for the winter.

To control strawberry clippers

. Locate strawberry plantings as far as possible from woodlots, hedgerows, etc.

. Destroy local populations of blackberry, raspberry and cinquefoil.

. If a bed is being replaced, immediately plow it under after harvest.

. Control weeds to limit the pollen sources for adult clippers.

. Some strawberry cultivars compensate for clipped buds by producing more blossoms. These varieties may need little or no control.

. Clippers enter plantings from wooded edges so expect more activity near these areas. Look for damage as soon as the strawberries bloom:

1. Choose five locations scattered across a field.

2. At each location, examine a 2-foot section of row and count the number of clipped buds.

3. Control is recommended if the average number of clipped buds per 2-foot sample is greater than 1.3 or if you see one or more adult clippers.

4.Contact the author at 581-3884 or dbarry@umext.maine.edu for a treatment recommendation.

Don Barry is an assistant scientist at the University of Maine Cooperative Extension. He can be reached at 581-3884 or dbarry@umext.maine.edu.