Abstract
Laboratory and field trials to determine the antifeedant/deterrent efficacy of guazatine triacetate in reducing feeding damage by Plathypena scabra (F.) to soybeans were conducted in 1976–78. Short-term (48 h) laboratory and field dosage/respone equations were calculated. Both equations were tempered by the presence of foliar phytotoxicity thresholds as they approached 86 and 50% protection, respectively. Short-term mortality was nominal at all rates, although mortality increased as exposure time (>48 h) and application rate increased. Increased application rates depressed development in a curvilinear fashion. The total cumulative damage eventually sustained, under each treatment, varied inversely with application rate. No effective systemic antifeedant/deterrent action was indicated.