I have received many calls from agents and farmers from across the east about Hessian fly. Dr. Randy Weisz just posted posted a short (2 minute) video alert about these Hessian Fly infestations and control options. Historically, most our Hessian fly issues have been centered in the far eastern counties, not only because of rotations (continuous wheat after beans), but I think because these areas have a unique climate from much of the rest of the state. As a result, I’m not too surprised to hear of these issues, but the damage has extended this year into areas of the Coastal Plain that are usually spared from Hessian fly.
Remember how wet last summer was? Stupid question. Some wheat was never harvested or was harvested late. We also had abundant summer rain that could have germinated some volunteer wheat in soybeans planted behind wheat. These conditions created abundant oversummering habitat for the fly, resulting in fall infestations. We are noticing these now since our wheat is picking up. This damage is already done, but what can we do to prevent damage from spring infestations?
First, it is important to scout your wheat to determine if symptoms you are seeing (yellowing, lack of vigorous growth, poor tillering, etc.) is a result of Hessian fly or something else. Other causal agents of these symptoms could include things like cold weather, lack of nitrogen, and wetness. Hessian fly are present as pupae in the fields at this time of the year. To scout for pupae, carefully dig up tillers below the soil and peel back the outer layers of leaves. Often pupae will fall out into the soil or will be feeding on the base of the plant behind these leaves.
Once you have determined the presence of Hessian fly, you need to make a decision about what to do with your field. Our resistant varieties are still holding up well, so you should focus on fields that are planted with a susceptible variety (listed here). Then separate your fields with susceptible varieties into three categories independent of planting date.
1) Fields that have some Hessian fly from the fall generation and are planted with a susceptible variety. Research from our state has shown that these fields will not benefit from a spring foliar spray. All fields with a susceptible variety likely have Hessian fly at some level. The vast majority of fields in our state fall into this category.