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Etiology

Role of Pythium in Sugarcane Stubble Decline: Effects on Plant Growth in Field Soil. J. W. Hoy, Department of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803; R. W. Schneider, Department of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803. Phytopathology 78:1692-1696. Accepted for publication 21 July 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-1692.

Sugarcane plants grown in sugarcane field soil treated with methyl bromide or metalaxyl showed significant increases in several components of root and shoot growth as compared with plants treated with fosetyl-Al or grown in untreated field soil. Metalaxyl applied at two rates completely controlled root rot caused by Pythium arrhenomanes in a pathogenicity test. In field experiments, significant yield increases were obtained in ratoon crops in metalaxyl-treated plots compared with untreated plots of two sugarcane cultivars. Experimental results suggest that P. arrhenomanes functions as a cryptic pathogen and causes significant reductions in sugarcane plant growth in field soil. These findings are discussed with respect to a syndrome in sugarcane known as stubble decline.