Winter Cover Crops Reduce Bacterial Wilt of Flue-cured Tobacco

Abstract

Bacterial wilt, caused by Ralstonia solanacearum, is a serious disease for tobacco farmers in the southeastern USA. The lack of suitable land for crop rotation and increased area of production on farms has resulted in shorter rotations, and increased losses due to bacterial wilt. Cover crops are rarely grown immediately before a tobacco crop because soil fumigation for nematode control necessitates early destruction of the cover crop. The microbial activity associated with growing winter cover crops may alter populations of R. solanacearum. This field study evaluated vetch, canola, or rye winter cover crops for suppression of bacterial wilt. Averaged over two tobacco crops, vetch preceding tobacco reduced bacterial wilt disease incidence 33% and increased crop yield and value (37% and 41%, respectively) when compared to a winter fallow. A two-year rotation involving both winter cover and summer rotation crops also showed that winter cover crops increased yields and reduced disease incidence when used following a nonsusceptible summer crop. Soybean rotation followed by a vetch winter cover reduced disease incidence 73% and increased yields 132% when compared to tobacco without a summer soybean rotation and with a bare winter fallow. Data suggest that losses to bacterial wilt can be reduced significantly with use of a vetch winter cover. Accepted for publication 14 February 2007. Published 22 May 2007.