Irrigation Timing And Tarnished Plant Bug Management –– Implications For Late Season Susceptibility To Tarnished Plant Bug And Crop Termination Decisions

The perennial nature of cotton is especially evident when, after preflower water deficit stress results in premature cutout, stress is relieved with mid-season rain or irrigation, and crop terminal growth re-commences. This late season resurgence of crop growth is attractive to insect pests such as tarnished plant bug. Decision makers frequently question whether the insect control termination guidelines in COTMAN (suspend insect control after NAWF=5+250 DD60s) should be adjusted to allow protection of the late maturing bolls in this type of regrowth cotton. In the first year of a planned 3 year study, we evaluated benefits of late season insecticide applications for control of tarnished plant bug. The field study was conducted in Marianna, AR at the UA Lon Mann Experiment Station. Irrigation timing was used to induce conditutions conducive for late season “re-growth” of cotton, and crop response to insect control was compared to non-irrigated, delayed and full season irrigated treatments. Late season infestations of tarnished plant bug were controlled with insecticide or sprays were terminated shortly after cutout. The experiment was arranged as a split plot, 3X5 factorial experiment with irrigation timing considered as main plots and insect control arranged as subplots. Results from the study will be discussed along with implications for decision making across variable fields.