Evaluating the Impact of Defoliation at Multiple Timings in Peanut

Numerous defoliating pests infest peanuts throughout the southern U.S. Current thresholds in peanuts are based on numbers of larvae and are static throughout the season. In general, infestations are random, variable in size, and not well understood. Knowing how peanuts respond to defoliation may be more precise than trying to manage crops based on insect infestation levels, especially in situations where multiple species occur concurrently. The objective of this research was to determine the response of peanut to defoliation at different times during the season and identify those times that are most sensitive to yield losses. Peanuts were planted at one location during 2014 and two locations during 2015 in Mississippi. Defoliation was applied as a randomized block design with four replications. Treatments included 100% defoliation at 35, 50, 65, 80, 95, and 110 days after emergence compared to a non-defoliated control. Each defoliation treatment resulted in a significant yield loss within two of the three site years. Losses ranged from 11.5% to 26.5%. Results from these experiments will be used to design additional research to define specific defoliation levels at critical stages of plant development. Ultimately, this research will be used to develop defoliation thresholds for insects in peanut.