Donald R. Cook, Leonard, Billy R. | 11/19/2004 1:36:57 AM
Donald R. Cook, Eugene "Gene" Burris and B. Rogers Leonard
Tarnished plant bugs, which have historically been a midseason pest of cotton, are now becoming a sporadic pest during seedling development. This is happening as agricultural conditions are changing, making it possible for more tarnished plant bugs to survive. These changes include more plant hosts because of more acres going into conservation reserve programs and an increase in conservation tillage. Another contributing factor is less use of insecticides because of boll weevil eradication and the increasing use of insect-resistant varieties.
Injury symptoms resulting from tarnished plant bug feeding during seedling development are similar to some symptoms resulting from thrips feeding. At-planting insecticides used to control thrips include seed treatments or application (granules and liquids) in the seed furrow at the time of planting.
Several at-planting insecticides recommended for thrips control were evaluated against tarnished plant bugs in 2001. The insecticide treatments included Cruiser 5FS, Gaucho 480FS, Orthene 80S and Temik 15G. Tarnished plant bug adults were caged on cotton seedlings from seven days after emergence until 26 days after emergence. Plants were infested at two- to three-day intervals, and mortality was determined 48 hours after each infestation.
Orthene and Gaucho resulted in 2.5 percent and 18.4 percent mortality of tarnished plant bug adults at seven days after emergence, respectively, and mortality declined to near 0 by 26 days after emergence. Cruiser produced 57.4 percent tarnished plant bug mortality seven days after emergence, and mortality declined to 13.4 percent by 26 days after emergence. Temik resulted in 76.6 percent tarnished plant bug mortality at seven days after emergence, with mortality declining to 29.9 percent by 26 days after emergence. Based on these results, Orthene and Gaucho provided little control of tarnished plant bugs at any evaluation. Cruiser provided low to moderate levels of tarnished plant bug control, and Temik provided moderate levels of control.
Temik and Cruiser offer some protection against tarnished plant bugs for about three weeks, but supplemental foliar insecticide applications may be necessary to control tarnished plant bugs during the seedling and floral bud development stages to minimize delays in crop maturity and improve early square retention, regardless of the at-planting insecticide used.
This article was published in the spring 2003 issue of Louisiana Agriculture.