The Hessian fly has not been a major pest in the mid-Atlantic states because of the practice of planting wheat after the “fly-free dates.” However, populations have recently been increasing as a result of changes in production practices. In 1998, economic impacts from Hessian fly were reported in numerous fields during the late spring. In some situations, entire fields were severely stunted and not worth harvesting. These fields had been planted in continuous wheat and/or in no-till situations with volunteer small grains present at the time of planting. In other fields, spring infestations caused plants to lodge near harvest with lodging ranging from 5 to 25 percent. All infested fields were planted after the “fly-free date”; however, the warm winter conditions apparently allowed an extra generation to develop during the last fall or early spring.
Since there are no effective chemical controls for Hessian fly, be sure to use the following combination of cultural practices to reduce the likelihood of Hessian fly damage: 1) avoid planting wheat following wheat and try to locate wheat away from areas that had Hessian fly problems the previous spring. Keep in mind that the adult flies disperse only short distances from their sites of emergence; 2) if possible, plow under infested wheat stubble as soon as possible after harvest. The adult Hessian fly is a weak insect that cannot work its way up through the soil; 3) keep down all growth of volunteer wheat to reduce fall egg laying, thus reducing the chances that the fly population will carry through to the following spring; 4) do not use wheat as a fall cover crop near fields with infestations or near fields to be used for grain. Rye or barley are less preferred host plants for Hessian fly, thus are suggested if planting cover crops prior to the fly-free date; 5) plant resistant or tolerant varieties. In 1998, a small grain variety trial at Georgetown indicated that certain varieties (SS EXP 3409D, SS EXP 3409R, Roane, and Pioneer 25R26) exhibited low to moderate stem lodging. Talk to your seed dealer to determine which variety characteristics are fly resistant; and 6) always plant after the fly-free date.
