With the upcoming planting of winter wheat, growers need to consider their options to manage grasshoppers this fall. Grasshopper populations decline through late summer and fall; however, they remain significant enough until the first hard freeze to threaten wheat seedlings as they emerge, says Gary Hein, University of Nebraska-Lincoln entomologist at the Panhandle Research and Extension Center at Scottsbluff.
"Emerging winter wheat has very limited foliage. Grasshoppers can easily keep the wheat clipped back completely, causing stand losses in the field margins," Hein says. "Growers need to monitor grasshopper densities in areas surrounding wheat fields."
Normal threshold densities in areas surrounding cropland need to be lowered because of damage potential. Densities in the range of 11 to 20 per square yard in non-crop borders surrounding newly planted wheat fields may be enough to cause significant loss, Hein says.
Several options, however, are available to help reduce the risk and/or manage developing problems. Hein' recommendations:
- Avoid early plantings in areas of high grasshopper activity to reduce damage potential. "Planting high risk fields near the end of the optimum planting window will reduce the time period that a field will need to be protected from grasshoppers in the fall."
- Increase the seeding density of wheat in field margins to compensate for partial stand loss. This may allow for a reasonable stand after grasshopper damage has run its course.
- If grasshopper populations surrounding wheat fields are high, insecticide control may be necessary to reduce their impact.
More detailed information about grasshopper control, including information about insecticides, can be found in Crop Watch, UNL Extension's crop production newsletter.