Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2000
Publication Date: N/A
Interpretive Summary: The tarnished plant bug is a serious pest of cotton grown in the southeastern United States. Plant bugs overwinter as adults and reproduce and increase in numbers in the spring on numerous species of wild plants, prior to moving into cotton in June and July. These wild hosts are found in marginal areas around fields, roads, and ditches, and the total area with wild hosts is small. A large experiment was conducted in the Delta of Mississippi in 1998 to evaluate control of plant bugs in cotton by reducing numbers of wild hosts found near fields with a herbicide applied in April. Four experimental areas each approximately square and three miles on a side were used. In one area, all good stands of wild hosts were treated in April with a herbicide that killed broad leaf plants. No treatments were applied in the other three areas which were checks. Samples taken prior to treatment and post- treatment showed that the herbicide treatment significantly reduced numbers of wild hosts in the areas treated as compared to similar areas in the untreated checks. Plant bug populations in the treated areas were also reduced 4.1- fold as compared to their populations in the checks. Plant bug numbers found in cotton in the treated and three check areas were very low during June, July, and early-August, and no effect on plant bug numbers found in cotton in the treated area could be detected.
Technical Abstract: An experiment was conducted in Sunflower and Washington Counties in the Delta of Mississippi in 1998 that evaluated control of tarnished plant bugs (TPB), Lygus lineolaris (Palisot de Beauvois), in cotton, Gossypium hirsutum L., by reduction in numbers of wild host plants found near fields with herbicides in April. Four experimental areas (3 check areas and 1 treated area) each approximately square and 4.8 km on a side were used. Marginal areas at least 100 m in length around ditches, fields, and roads with good stands of wild hosts in all four experimental areas were chosen for treatment and/or sampling. Wild host plant densities in the sample areas in the four experimental areas were not significantly different in pre-treatment counts. Treatment of the sample areas with a combination of mecoprop + 2, 4-D + dicamba at 1.55 + 0.54 + 0.17 kg AI/ha significantly reduced host plant density as compared to host plant density in the check areas. TPB populations in the treated sample areas declined 4.1-fold as compared to TPB populations found in the sample areas in the three check areas, when sampled 2-3 weeks after treatment. Cotton fields were sampled weekly in the treated area (14 fields) and three check areas (33 fields) for TPB from the 2nd week in June through the 1st week of August. TPB numbers found in the cotton were very low and no effect on TPB numbers found in cotton in the treated area could be detected.