The following information was prepared by Kevin Wanner (MSU Extension Entomologist). Emerging winter wheat can be particularly vulnerable to damage by grasshoppers. The larger adult stage grasshoppers are more difficult to control and can move into emerging winter wheat fields from surrounding grassy areas. Treatment thresholds for emerging winter wheat are lower, 3-7 per square yard within the field, or 11-20 per square yard around the margin probably requires treatment. Border treatments applied as insecticidal sprays or seed treatments are the main recommendation for protecting emerging winter wheat. Typically, spraying 150 feet beyond the edge of the crop or 1-2 passes with treated seed around the perimeter of the field is a sufficient border. Adult grasshoppers are more difficult to control, and the higher end of the label rate is recommended. If grasshopper populations are very high they are difficult to control, borders up to ¼ of a mile and repeated applications may need to be considered. When applying border sprays, timing is important. Border sprays beyond the edge of the crop need to be applied just before the wheat emerges; if it is applied too early there may not be enough residual, it is applied too late, the damage may have already occurred. Systemic seed treatments eliminate the timing concern, but systemic insecticides require feeding to be active, but damage should be slowed considerably. For information about seed treatment and foliar sprays for grasshoppers in winter wheat, please google the North Dakota Field Crop Insect Management guide or contact Chouteau County Extension at 406-622-3751.
Montana State University, U.S. Department of Agriculture and Montana Counties Cooperating. MSU Extension is an equal opportunity/affirmative action provider of educational outreach.
