By Scout Nelson
Grasshoppers continue to be an important concern for farmers across South Dakota during the growing season. Areas that have experienced high grasshopper populations in recent years are once again seeing increased activity. Combined with ongoing drought conditions in many parts of the state, these insects may cause greater crop injury if populations are not monitored and managed.
Adam Varenhorst, Associate Professor and SDSU Extension Field Crop Entomologist, along with Philip Rozeboom, Amanda Bachmann, Bradley McManus, and Patrick Wagner, highlighted the importance of scouting fields regularly and acting before grasshopper populations reach damaging levels.
Field observations indicate that grasshopper nymphs are becoming more active, and some locations are already approaching treatment thresholds. The three pest species most found in eastern South Dakota at this time are the redlegged grasshopper, differential grasshopper, and twostriped grasshopper. These insects feed on a wide range of plants and may be found in crops, pastures, roadsides, and home gardens.
Grasshoppers can cause significant feeding damage by removing plant leaves and reducing crop growth. Because they are not selective feeders, they can move easily between different plant types when food sources become limited.
Regular scouting is the best way to detect problems early. A common method involves walking through the field in a horseshoe-shaped pattern and stopping about every 50 feet to count grasshoppers within a square yard area. This process helps determine whether populations have reached economic thresholds.
Current recommendations suggest treatment when there are 21 to 40 grasshoppers per square yard along field margins or 8 to 14 grasshoppers per square yard within fields. Managing grasshoppers during the nymph stage is generally more effective because younger insects are smaller and easier to control. Once grasshoppers become adults, management becomes more difficult and often requires higher insecticide rates.
Farmers should always read and follow product labels carefully and avoid relying on the lowest labeled insecticide rates for grasshopper control. If populations exceed thresholds, producers can consult the latest South Dakota Pest Management Guides for approved management options.
Photo Credit: pexels-tudsaput-eusawas
Categories: South Dakota, General