Leaf Blight of Onions in Barbados Caused by Xanthomonas campestris. Litta Paulraj, Department of Biology, University of the West Indies, P.O. Box 64, Bridgetown, Barbados. Leonard W. O’Garro, Department of Biology, University of the West Indies, P.O. Box 64, Bridgetown, Barbados. Plant Dis. 77:198-201. Accepted for publication 13 October 1992. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0198.

A leaf blight of onions occurring in Barbados is characterized by the rapid necrosis and dieback of leaves under humid conditions. A bacterium, isolated from lesions, induced water-soaked lesions on onion leaves within 3 days. This bacterium was identified as Xanthomonas campestris on the basis of fatty acid analysis and other biochemical and physiological tests. The severity of the disease declined by 93–99% if plants were first treated with Erwinia herbicola, but it increased if Xanthomonas preceded E. herbicola. This is the first known description of the causal agent of the leaf blight of onion in Barbados.