Even though the threshold of one per six feet of row was not reached, greater than twenty percent damage was experienced where control was not effected. Yield increases were observed in the three treated plots, with the pyrethroid showing a significant yield increase over the other three treaments. The use of pyrethroid sprays on BT cotton decreased bollworm, fall armyworm and stink bug populations and would be the preferred treatment for late season insect control. Cotton yields increased when insecticide treatments were used on Bt cotton with pyrethroid sprays providing a significantly higher yield when compared to the other treatments. The use of scouting to determine the necessity for insecticide sprays remains the number one method of determining environmentally safe and effective insecticide scheduling.
More study is needed relating to stink bug thresholds and treatment triggers.
Since the successful elimination of the boll weevil as an economic pest, bollworm and tobacco budworm have become the primary cotton insect pests in Georgia. The introduction of transgenic Bt cottons has again redefined the cotton insect control picture. The use of transgenic Bt cottons has greatly diminished the demands on the cotton producers relating to bollworm and tobacco budworm control by further reducing the need for repeated insect sprays to decrease losses from these two insect pests. Beginning in 1996, Georgia farmers began to use the Bt varieties for cotton on a wide spread basis. This figure grew to 37 percent in 1997 and further expanded to 55 percent in 1998.