THRIPS INJURY CAN REDUCE PEANUT YIELD AND QUALITY UNDER CONDITIONS OFMULTIPLE STRESS

Severe injury from tobacco thrips [Frankliniella fusca (Hinds)] to see dling peanut (Arachis hypogaea L.) has not been documented to reduce y ield and quality. However, thrips injury may be economically important when combined with another factor, such as postemergence herbicide in jury. This note reports results of a field experiment in which control of tobacco thrips during an unusually dry early season greatly increa sed peanut seed yield and quality. 'Florunner' peanut was grown using preplant and postemergence herbicides for weed control. Treatments con sisted of an untreated control and four labeled insecticides applied a t planting or soon after crop emergence. Populations of adult tobacco thrips were significantly suppressed by aldicarb [2-methyl-2-(methylth io) propionaldehyde O-(methylcarbamoyl) oxime]; all insecticides signi ficantly suppressed immature thrips. Aldicarb, the most efficacious in secticide treatment, significantly improved peanut yield by 32% and qu ality as determined by percentage of total sound mature kernels. All b ut one of the remaining insecticide treatments significantly improved seed yield, with increases ranging from 9 to 31%, Rainfall was extreme ly low early in the growing season, and (based on 41 yr of records at the site) drier conditions occur 10% of the time. This is a frequency great enough to matter, but low enough to make further research diffic ult. The observations reported here suggest that early-season moisture stress intensifies peanut yield and quality losses associated with co mbined injury from thrips and postemergence herbicides.