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Relay Strip Cropping and Food Sprays for Managing Bollworms and Cotton Aphids

J. E. Slosser, M. N. Parajulee and D. G. Bordovsky


 
ABSTRACT

Studies were conducted at the Texas Agricultural Experiment Station at Munday in1996 to evaluate relay strip crops in combination with a food spray to enhance biological control of bollworms, Heliothis zea (Boddie), and cotton aphids, Aphis gossypii Glover, in cotton. The relay crops included fall plantings of hairy vetch and canola, and a spring planting of grain sorghum. Cotton was planted between the relay crops or was isolated from the relay crops. Treatments within the two cotton systems included an untreated check plot, a plot sprayed with sugar + yeast (food spray) during summer to attract and hold predator insects, a plot sprayed with biological ("soft") insecticides for bollworm and cotton aphid control (Bacillus thuringiensis and pymetrozine, respectively), and a plot sprayed with harsh insecticides for bollworm and cotton aphid control (zeta cypermethrin and dicrotophos, respectively). A split-plot experimental design, with three replications, was used; whole plots were relay and isolated cotton systems, and subplots were the four food/chemical treatments. Predator numbers were monitored with a vacuum sampler once a week in relay crops and cotton. Bollworms and cotton aphids were monitored visually once a week in cotton during July and August. Total predator numbers were higher in cotton adjacent to relay crops, compared to predator numbers in isolated cotton, only during June and July. The food spray did not enhance attraction and retention of predators in relay or isolated cotton systems. Bollworm larval numbers were significantly higher in relay cotton that was treated with the food spray, compared to the untreated check, in late July. The food spray and pymetrozine treatments reduced cotton aphids more effectively in the relay cropping system than in the isolated system.



Reprinted from Proceedings of the 2000 Beltwide Cotton Conferences pp. 982 - 984
©National Cotton Council, Memphis TN

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Document last modified Saturday, Jun 17 2000