FINAL IRRIGATION TIMING AND LATE SEASON CROP SUSCEPTIBILITY TO TARNISHED PLANT BUG (LYGUS LINEOLARIS PALISOT DE BEAUVOIS) 2005 – USING COTMAN TO MAKE CROP TERMINATION DECISIONS

摘要

Research is underway in Arkansas to establish and validate end-of-season crop management guides for timing final furrow irrigation and for terminating insecticide applications for tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)). In the 2nd year of a planned 3-year study, we have examined interactions of late season irrigation and insect control in a field trial on the University of Arkansas Lon Mann Cotton Research Station in Marianna. With rains in late August, termination of irrigationprior to physiological cutout (mean NAWF =5) did not result in significant yield penalties compared to later termination dates. Late irrigations did delay boll opening. Plant bug numbers late season were at low to moderate levels but exceeded some stateaction thresholds (a range of 3 to 8 bugs/3 ft of row in drop cloth samples). Late season insecticide sprays extending out to NAWF=5+413 DD60s reduced bug numbers in protected treatments but did not result in significant yield differences compared to early terminated (NAWF=7) treatments. There were no significant irrigation*insecticide interactions observed with lint yield. Results from the 2004 and 2005 seasons of research in the Central Eastern Arkansas production region coupled with data from previous studies in NE Arkansas indicate that the insect control termination guide in COTMAN that has been in use for heliothine caterpillars and boll weevils (NAWF=5 +350 DD60s) is more than sufficient for late season plant bug management, and timing of final furrow irrigation also may be appropriate at this same crop stage.