Black root rot of cotton in Australia: the host, the pathogen and disease management

Black root rot is a seedling disease caused by the soil-borne fungal pathogen Thielaviopsis basicola, a species with a worldwide distribution. Diseased plants show blackening of the roots and a reduced number of lateral roots, stunted or slow growth, and delayed flowering or maturity. It was first detected in cotton in Australia in 1989, and by 2004, T. basicola reached all cotton-growing regions in New South Wales and Queensland and the disease was declared as an Australian pandemic. This review covers aspects of the disease that have implications in black root rot spread, severity and management, including the biology and ecology of T. basicola, host range and specificity, chemical and biological control of T. basicola in cotton cropping systems, and crop rotations and host resistance. This review is of special interest to Australian readers; however, the incorporation of ample information on the biology of the pathogen, its interactions with plants and it relation to disease management will benefit readers worldwide.