Tarnished plant bug
The most important insect pest of Minnesota-grown strawberries is the tarnished plant bug (TPB). Heavily infested fruit is severely deformed and unappealing.
TPB adults are about 1/4 inch long and oval shaped. They are brown to black with yellow or white patches. They are easily identified by the yellow markings behind the head which vary from a V shape to a Y shape to a heart shape. The nymph is similar to the adult only smaller. They are green with black spots.
Adult TPB emerge from overwintering sites in early spring and prefer to feed on the rapidly growing plants just beginning their spring growth. The adults are active for several weeks prior to the opening of strawberry flowers. At flowering time the females mate and insert their eggs into the flower blossoms. The female will lay 3 to 4 eggs per day. The nymphs emerge a week or so later and begin feeding on the flower tissue. There can be 2 to 5 generations per year. In the fall the adults look for leaf litter, tall grass, or weedy areas in which to spend the winter.
Both adults and nymphs injure strawberry fruit by inserting their piercing mouth parts into the flowers and young fruit. This kills the developing seeds and the surrounding tissue resulting in a deformed fruit often called a "button berry". The adults are responsible for most of the damage to strawberry flowers and fruit. Damage can vary from partial to severe depending on the amount of feeding and the numbers of bugs present.
Inspect for TPB soon after strawberry plants have begun to grow in the spring. Look for adults feeding on the emerging buds in either the green or white stage. Research indicates that the best strategy is to manage adult numbers at this stage
- Remove leaf litter to reduce the number of overwintering sites for TPB.
- Remove weeds as they can provide habitat for adults to feed and overwinter.
- Keep lawn areas properly mowed so that the lawn does not become a TPB habitat area.
- If your patch is small enough, you can physically remove TPB by tapping the flowers and dislodging the insects into a pan of soapy water.
- Renovate the patch to remove potential habitat and reduce insect numbers.
Make spray applications on the basis of scouting results when TPB adults are found in either the green or white stage. Effective insecticides are permethrin, carbaryl, and malathion. Be sure to read and follow all pesticide label directions.