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United States Department of Agriculture

Agricultural Research Service

Title: Influence of cover crops on insect pests and predators in conservation tillage cotton

Authors
item Tillman, Patricia
item Schomberg, Harry
item Phatak, Sharad - UNIVERSITY OF GEORGIA
item Mullinix, B - UNIVERSITY OF GEORGIA
item Timper, Patricia
item Weyers, Sharon
item Olson, Dawn

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 10, 2004
Publication Date: August 1, 2004
Citation: Tillman, P.G., Schomberg, H.H., Phatak, S., Mullinix, B., Timper, P., Lachnicht, S., Olson, D.M. 2004. Influence of cover crops on insect pests and predators in conservation tillage cotton. Journal of Economic Entomology. 97(4):1217-1232.

Interpretive Summary: As a result of frequent and intense disturbance, many agricultural systems are recognized as particularly difficult environments for natural enemies. Conservation tillage and cover crops can help reduce production costs by increasing beneficial insects and improving soil water relationships and long-term soil productivity. In the fall of 2000, an on-farm sustainable agricultural research project was established for cotton in South Georgia and conducted for two years. The main objective was to develop cover crop systems for conservation tillage cotton that increase beneficial insects. The four cover crop treatments included cereal rye, crimson clover, a mixture of three legumes - balansa clover, crimson clover, and hairy vetch, and a combination of rye in the center of the cotton row with the legume mixture between these centers. Controls were conventionally-tilled cotton fields not planted in winter cover crops. The cotton bollworm and tobacco budworm were the only pests that exceeded their economic threshold. For both years, the number of dates reaching the economic threshold was less for crimson clover/cotton and rye/cotton than for control cotton largely due to predation by fire ants and the big-eyed bug. In 2001, cotton seed yields were higher for cotton with crimson clover and legume mixture-rye cover crops compared to cotton controls. In 2002, all cover crop cotton fields, except for the rye fields, had higher seed cotton yields relative to control fields. Therefore, planting a winter cover crop resulted in overall more profitable cotton production compared to leaving a field fallow in the winter.

Technical Abstract: In the fall of 2000 an on-farm sustainable agricultural research project was established for cotton, Gossypium hirsutum L., in South Georgia and conducted for two years. The objectives were to develop cover crop systems for conservation tillage cotton that enhance habitat for ground, plant and soil-dwelling beneficial arthropods, reduce risks of belowground plant parasitism by nematodes, improve nutrient cycling and water availability, and reduce costs of cotton production and to enhance producer understanding of sustainable principles and practices. The four cover crop treatments included cereal rye (Secale cereale L.), crimson clover (Trifolium incarnatum L.), a mixture of three legumes - balansa clover (Trifolium michelianum Savi), crimson clover, and hairy vetch (Vicia villosa Roth.), and a combination of rye in the center of the cotton row with the legume mixture between these centers. Controls were conventionally-tilled cotton fields not planted in winter cover crops. This paper is a report of the results on pest and predator insects in cover crops and cotton for the duration of the project in Tifton, Georgia. Cotton aphids, Aphis gossypii Glover, were present in most cover crops, but the impact of cover crops on these pests in cotton did not follow a particular pattern. In cotton, stink bugs, Nezara viridula (L.), Euschistus servus (Say), Acrosternum hilare (Say), and Oebalus pugnax (F.), and the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), were not significantly different between cover crop and control cotton. In both years of this study, the heliothines, Heliothis virescens (F.) and Helicoverpa zea (Boddie), were the only pests that exceeded their economic threshold. The aphidophagus coccinellids, Hippodamia convergens Guerin-Meneville, Coccinella septempunctata [L.], Coleomegilla maculata (DeGreer) and Harmonia axyridis (Pallas), associated with aphids in cover crops built up in the spring and sometimes, but not always, appeared to disperse from the cover crops to cotton to feed on the cotton aphid. Fire ants, Solenopsis invicta Buren, were generally higher in conservation-tillage cotton fields planted in winter cover crops than in conventional-tillage cotton fields left fallow during the winter. Geocoris punctipes (Say) were higher in cotton fields previously planted in cover crops compared to control fields for only one year. Orius insidiosus (Say) were not significantly different between cover crop and control cotton fields. In 2001, cotton seed yields were higher only for cotton with crimson clover and legume mixture-rye cover crops compared to control cotton. In 2002, all cover crop cotton fields, except for the rye fields, had higher seed cotton yields relative to control fields. Even though benefits of the standard cover crops and two new cover crop treatments were variable in this two-year study, planting a winter cover crop resulted in overall more profitable cotton production compared to leaving a field fallow in the winter.

Last Modified: 7/27/2014