Studies on the bacterial blight (Wilt) of Tapioca incited by Xanthomonas manihotis (Arthaud-Berthet) Starr

Abstract

The bacterial blight of tapioca, incited by Xanthomonas manihotis (Arthaud-Berthet) Starr, probably the most serious of all the diseases recorded on the plant, was reported sporadically from different parts of Kerala since 1975. The disease is characterised by loss of turgidity, shrivelling and wilting of leaves, gum extraction, die-back and death of shoots, vascular discolouration of stem and roots and damage and decay of tubers. The pathogen was confirmed to be Xanthomonas manihotis from morphological, physiological and biochemical studies coupled with symptomatology and host specificity. The pathogenicity was confirmed on tapioca using different methods of artificial inoculation, of which inoculation after nipping the bud was found to be the best.