Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 12/1/2001
Publication Date: 1/15/2002
Citation: Interpretive Summary: The tarnished plant bug (TPB)is a major pest of cotton. In 2001, TPB and western plant bugs caused an estimated loss of 300,000 bales. In addition to yield loss, TPB can cause delays in crop maturity. "Economic thresholds" are guidelines used extensively in cotton production for determining whether applying a treatment to a crop will result in an increase in crop value greater than the cost of the treatment. At some point in the season the crop is no longer susceptible to insects, and economic thresholds become irrelevant. The crop is beyond its final stage of susceptibility, and subsequent insecticide applications are uneconomical. The question of when a cotton crop is "safe" from late season insect pests has been has been the focus of intense research during the last 20 years. Research efforts have yielded a simple crop monitoring procedure and crop termination rule that allow a decision maker to define the final stage of crop susceptibility for a particular pest. After that point, the decision maker can ignore future infestations of those pests. The process is easily performed using the COTMAN system. Using COTMAN, we found that despite significant high tarnished plant bug numbers and associated feeding injury, no yield penalty was observed following TPB infestations initiated at 150, 296 or 375 DD60s after physiological cutout. Results from this one season of research indicate that insect control termination rules that have been in use for heliothine caterpillars and boll weevils (cutout +350 DD60s) are more than sufficient for late season tarnished plant bug management.
Technical Abstract: End-of-season insect control termination rules for tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)) were evaluated in a field trial in Northeastern Arkansas in fall 2001. Natural infestations were augmented with release of 3 to 5 nymphs (3rd instar) per plant starting at about 1 week after physiological cutout (NAWF=5) and at the time of the latest possible cutout date for the area, 9 Aug. Additional releases were made over the next 3 weeks. TPB infestations were initiated at 150, 296 or 375 DD60s after physiological cutout. Crop injury observations made in late August indicated significant TPB feeding injury to upper canopy bolls. Yield data indicated no yield penalty from late season infestations compared to untreated plots or to protected cotton that had received 4 applications of Centric 40 WG (thiamethoxam) (3 oz/ac); the last application occurred at 488 DD60s past physiological cutout. Lint yields ranged from 1186 to 1253 lb/ac. Results from this one season of research indicate that insect control termination rules that have been in use for heliothine caterpillars and boll weevils (cutout +350 DD60s) are more than sufficient for late season plant bug management.