Impact of Irrigation Timing on Tarnished Plant Bug Populations and Yield of Cotton

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is the most significant insect pest of cotton, Gossypium hirsutum (L.), in the mid-southern United States (Arkansas, Louisiana, Mississippi, Missouri, and Tennessee). Past research has shown the impact that planting date, nitrogen rate, and variety selection has on tarnished plant bug populations, but a paucity of data exists on the effect irrigation timing has on tarnished plant bug. Experiments were conducted at the Mississippi State University Delta Research and Extension Center in Stoneville, MS to determine if insecticide applications targeting the tarnished plant bug could be reduced in response to irrigation timings. Treatments were in a strip-block arrangement, with the main plot factor being irrigations initiated at squaring, first flower, peak flower, and a non-irrigated control. The sub-plot factor was tarnished plant bug management that consisted of insecticide applications made weekly, at threshold, and a non-treated control. Overall, insecticide applications for tarnished plant bug increase yield. Irrigation initiated at squaring resulted in tarnished plant bugs exceeding the recommended treatment threshold significantly more than when irrigations were initiated later in the growing season. Also, when irrigation was postponed until peak flower, no yield loss or delay in maturity was observed. These results indicate that irrigation timing could be a potential cultural control practice that reduces the number of insecticide applications targeting tarnished plant bug populations in Mid-South cotton.