INTERACTION OF EARLY-SEASON HERBICIDE INJURY, TOBACCO THRIPS INJURY, AND CULTIVAR ON PEANUT

Peanut (Arachis hypogaea L.) can tolerate severe early-season injury b y tobacco thrips [Frankliniella fusca (Hinds)], and controlling popula tions usually is not recommended in the southeastern USA. Field observ ations, however, indicated that injury from early-season thrips infest ation may exacerbate injury caused to peanut by early postemergence he rbicide application. Studies were conducted near Jay and Marianna, FL, during 1989 and 1990 to evaluate the interaction between peanut culti var, preplant incorporated application of vernolate (S-propyl di-propy lcarbamothioate), postemergence application of alachlor -N-(2,6-diethy lphenyl)-N-(methoxymethyl)acetamide] plus paraquat (1,1'-dimethyl-4,4' -bipyridinium ion) and thrips suppression with foliar application of a cephate (O,S-dimethyl acetylphosphoroamidothioate). 'Southern Runner' was more susceptible than 'Florunner' to early-season stress from inse ct and herbicide injury. Injury from preplant incorporated herbicide a lone, postemergence herbicide alone, or thrips alone usually was not s ufficient to cause long-term damage to peanut growth or to adversely a ffect peanut maturity or yield. When two or all of these factors impac ted peanut simultaneously, however, delays in crop maturity and reduce d yields (up to 11%) were often observed. Early-season suppression of tobacco thrips often alleviated the detrimental effects to peanut. Sup pression of thrips populations should receive greater consideration in future integrated pest management programs of peanut to avoid interac tions with early-season herbicide stress, especially when growing Sout hern Runner.