Plant Health Initiative

Grasshopper - Agronomic Impact

Grasshopper adults can consume the entire leaf, leaving on the major veins. Photo credit: Marlin Rice, Iowa State University

Grasshoppers are relatively large insects that are capable of doing considerable damage in a very short time. Large numbers of grasshopper nymphs can develop in tall weedy areas, attracting little attention. However, when they become winged adults, they can fly greater distances and suddenly appear in crop fields.

Nymphs may consume the entire soybean seedling. On more mature plants, both nymphs and adult grasshoppers eat irregular holes in the leaves. Adult grasshoppers will also feed on pods.

Reductions in yield can occur during any crop stage although the pod-forming and pod-filling stages are at greater risk than other plant stages. According to Marlin Rice, Extension entomologist at Iowa State University, a 40 percent leaf loss during any vegetative stage will result in only a 3 to 7 percent yield reduction. Defoliation of 20 percent during the pod-forming and filling stages will result in similar yield reductions.

Sources
Grasshoppers get the jump on soybean, Marlin Rice, Iowa State University Integrated Crop Management newsletter