ABSTRACT

Broadleaf weeds found in marginal areas by fields, roads, and ditches were controlled with the herbicides Trimec® or Strike 3TM in nine-square-mile areas of the Mississippi Delta in March or April of 1999, 2000, and 2001. These weeds serve as early season food and reproductive hosts for tarnished plant bugs and population buildups occur on these weeds prior to movement of plant bugs into cotton. Cotton fields in the treated areas and in untreated nine-square-mile areas were sampled for tarnished plant bugs weekly during June and July of all three years. Overall mean numbers of tarnished plant bug adults and nymphs were significantly lower in cotton in the treated areas. The average reduction in overall mean numbers of plant bugs was 45.5 and 47% for adults and nymphs, respectively, for the three-year period. Grower costs for insecticides used to control plant bugs were lower in cotton in the treated test sites in all three years. Elimination of broadleaf weeds was found to be an effective method for reducing numbers of plant bugs in cotton. However, it did not reduce numbers of tarnished plant bugs in any year to a level in cotton where additional control with insecticides was not needed.