Previous researchers have used mechanical injury to simulate insect feeding injury in cotton (Gossipum hirstum). Such techniques are convenient compared to using insects; however, results have been inconsistent. In this experiment, comparisons of plant response to mechanical injury and insect feeding at two early stages of crop development were evaluated in a field study in Northeast Arkansas. Terminals of plants were mechanically removed using forceps or infested with one tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)) nymph at the 1st or 4th true leaf stage. One 3rd instar tarnished plant bug nymph was released per plant for insect injury. An untreated check also was included. The expert system, COTMAN, was used for crop monitoring. At 10-days after treatment the untreated check contained more plants with actively growing terminals compared to injured plants; there were no differences between mechanical or tarnished plant bug injury. All injury treatments resulted in a delay of floral bud (square) initiation compared to the untreated check. Injury treatments also reduced the number of sympodial branches compared to the untreated check, but plants mechanically injured at 4th true leaf had fewer sympodial branches than all other treatments at the time of 1st flower. By the end of the season plants had compensated for injury. There were no differences between treatments in days to physiological cutout, mean maturity date or seed cotton yield. During most years in Northeast Arkansas a delay would force the crop to mature when insect pest pressure is high and weather conditions unfavorable.
Species 1: Heteroptera Miridae Lygus lineolaris (tarnished plant bug)
Keywords: COTMAN crop monitoring system
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