RESPONSE TO MECHANICAL AND TARNISHED PLANT BUG (LYGUS LINEOLARIS) INJURY OF SEEDLING COTTON (GOSSYPIUM HIRSUTUM)

摘要

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 1st or 4th-leaf stage, plant terminals were mechanically removed using forceps or infested with one 3rd instar plant bug. Injury treatments along with an untreated check were monitored through cutout using COTMAN~(TM) End of season plant mapping also was performed. Compared to the check, bug and manual injury treatments delayed squaring and days to 1st flower by one week, and also reduced the number of sympodial nodes at 1st 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 1st 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 3rd 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.