Grasshopper activity is picking up recently across the state. Similar to cotton, they are a sporadic pest that can sometimes affect yield. Their populations are typically restricted to field edges, but they can move throughout a field quickly when populations are high following drought situations.
As a result, size and number of grasshoppers plus weather should be taken into account for management decisions.
Grasshoppers in the genus Melanoplus are common in Alabama and will feed on a variety of plants, including corn. They overwinter as eggs in the soil which are destroyed during tillage. Therefore, no-till fields or fields near undisturbed areas are at the highest risk.
Grasshopper nymphs are more restricted in their movement and will stay near their hatching site since they are unable to fly. Adult grasshoppers, present now in many areas, are much more mobile.
Grasshoppers will feed on the leaves of vegetative corn and can continue to feed on pollinating silks or developing kernels. Control is difficult because they are highly mobile, moving in and out of fields on a regular basis, and adults are hard to kill with insecticides.
To scout for grasshoppers, start at the field borders then move to several spaces throughout the field. If severe defoliation is occurring and there are numerous grasshoppers per square yard, treatment may be warranted. If the grasshoppers have not moved throughout the entire field, spot treatments or border sprays can be used.
However, keep an eye out for re-infestation since these are mobile pests that do not all hatch at the same time. Several insecticides are labeled for grasshoppers in corn and other non-crop areas if treated is needed.