The main period, when yield reductions due to defoliation may occur, is when plants are 60 to 90 days old. Pests associated with plant structures at or below the soil surface have the greatest potential for reducing peanut yields. The lesser cornstalk borer and granulate cutworm arethe pests most commonly encountered feeding in this manner. Most lesser cornstalk borer infestations develop during July and August after pegging has begun. Developing pods are often scarred by surface feeding and hollowed by tunneling of larvae.
Granulate cutworms feed primarily at night on plant foliage, pegs, and pods.
During the day, the larvae are typically found on the soil surface beneath peanut foliage. Diazinon granules applied to the soil surface over the pegging zone and around the base of the plants will usually control, or at least suppress, both of these pests. For more detailed information on insect pests of peanuts and control considerations, consult OSU Extension CR-608, Peanut Production Guide for Oklahoma. Also, refer to F-7313 for control suggestions for pests of other vegetable crops. The peanut fruit approaches maturity about 60 days after flowering.