Early Planting and Potential for Insect Problems in Small Grains

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

In recent years, there has been a trend in some areas of the state towards early wheat planting. Unfortunately, early planting can result in a number of insect problems including aphids, which vector barley yellow dwarf virus, direct damage from green bug aphids, Hessian fly and armyworms. . Planting after the fly free date (Oct 3 – New Castle County, Oct 8 – Kent County, and Oct 10- Sussex County) can help to reduce losses from insect pests.

As a reminder, although we have not seen significant problems with Hessian fly in wheat for a number of years, I do see it at low levels each year. As indicated in the publication (ANR-1069) Biology and Management of Hessian Fly in the Southeast, “correct varietal selection can be an effective method of Hessian fly management. In most cases, resistance is based on a single gene present in the variety that must match a gene in the Hessian fly. Unfortunately, the Hessian fly can overcome host plant resistance mechanisms, resulting in the formation of new strains called biotypes. To be effective, wheat varieties must be specifically resistant to the local Hessian fly genotype.” Some varieties marketed in our area are screened for biotype L. Unfortunately, we have no recent data regarding the biotype(s) of Hessian fly present in Delaware wheat fields. In the past it was biotype L but we currently have no data as to whether that is still the case. Therefore, a combination of strategies including planting after the fly free date for your area, are still needed to reduce losses from Hessian fly.

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