ABSTRACT

Comparison of plant response to mechanical injury and tarnished plant bug (Lygus lineolaris) feeding at two early stages of crop development were made in a field study in Northeast Arkansas in 2001. At either the 1^st or 4^th-leaf stage, plant terminals were mechanically removed using forceps or infested with one 3^rd instar plant bug. Injury treatments along with an untreated check were monitored through cutout using COTMAN™. End of season plant mapping also was performed. Compared to the check, bug and manual injury treatments delayed squaring and days to 1^st flower by one week, and also reduced the number of sympodial nodes at 1^st flower. While plant response was similar at the 1-leaf stage, it was not at the 4-leaf stage. Plants injured mechanically at the 4-leaf stage had fewer sympodial nodes on all sample dates and produced a higher percent of their yield on monopodial branches compared to plants infested with one plant bug nymph. After 1^st flower, differences in crop maturity were not apparent; this was probably due to soil variability in the experimental plots and fall weather conditions conducive to maturing a late crop. Terminal injury had no effect on final seed cotton yield. The results from this experiment indicate that the plant response to feeding injury caused by one 3^rd instar plant bug during the 1-leaf stage were comparable to plants mechanically injured. When injury was delayed until the 4-leaf stage, plants did not respond equally to mechanical and plant bug injury.