Location: Southern Insect Management ResearchTitle: Development of a plant based threshold for tarnished plant bug (Hemiptera: miridae) in cotton Author
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2012
Publication Date: 12/15/2012
Citation: Gore, J., Catchot, A., Musser, F., Greene, J., Leonard, R., Cook, D., Snodgrass, G.L., Jackson, R.E. 2012. Development of a plant based threshold for tarnished plant bug (Hemiptera: miridae) in cotton. Journal of Economic Entomology. 105:207-2014. Interpretive Summary: Economic thresholds for tarnished plant bugs in cotton are primarily based on numbers of insects captured using a particular sampling method. This study evaluated the utility of a plant-based threshold consisting of sampling for “dirty squares”. These dirty squares are stained flower buds caused by tarnished plant bug defecation. The stains provide a measure of the level of tarnished plant bugs within the field. Various thresholds based on percent dirty squares were compared to the current threshold with a drop cloth or automatic weekly applications. Numbers of insecticide applications, yields, and economic returns were similar for the 10 percent dirty square threshold compared to that of the current drop cloth threshold. These results suggest that a threshold of 10 percent dirty squares could be used to trigger insecticide applications targeting tarnished plant bugs in flowering cotton.
Technical Abstract: The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is the most important insect pest of cotton, Gossypium hirsutum L., in the midsouthern United States. It is almost exclusively controlled with foliar insecticide applications, and sampling methods and thresholds need to be revisited. The current experiment was designed to establish a plant-based threshold during the flowering period of cotton development. Experiments were conducted in Mississippi in 2005 and 2006, Arkansas in 2005, and Louisiana in 2005 through 2008. Treatments consisted of various combinations of thresholds based on percent dirty squares that were compared to the current threshold with a drop cloth (3 tarnished plant bugs per 1.5 row m) or automatic weekly applications. Treatments consisted of 5, 10, 20, and 30 percent dirty squares. Each plot was sampled weekly, and insecticides were applied when the mean of all replications of a particular treatment reached or exceeded the designated threshold. At the end of the season, plots were harvested and lint yields were recorded. Significant differences were observed in the number of applications and cotton yields among the different threshold treatments. In general, a threshold of 10 percent dirty squares resulted in a similar number of insecticide applications, yields, and economic returns when compared to that observed with the current drop cloth threshold. These results suggest that a threshold of 10 percent dirty squares could be used to trigger insecticide applications targeting tarnished plant bugs in flowering cotton.