First report of colletotrichum truncatum causing stem cankers on jatropha curcas in Burkina Faso

Abstract

A new disease was identified on the biofuel crop Jatropha curcas in 2012 in Burkina Faso that is causing serious yield losses. The disease was found to be widespread in both Sissili and Comoé Provinces. It causes characteristic leaf lesions, fruit necrosis, and cankers on young stems and branches. There was evidence of multiple infections on plants over the growing season, with regrowth evident from below old cankers, but there was little fruit production from infected branches. A detailed monitoring and assessment was undertaken of the disease progress in a severely infected field, over a 7-week period. The disease symptoms progressed from chlorosis through a necrotic phase and, in approximately 83% of replicates, stem cankers developed that resulted in dieback and lodging of branches. Colletotrichum truncatum and a member of the species complex C. gloeosporioides sensu lato were consistently isolated from fresh stem samples showing early symptoms (chlorosis). Koch’s postulates were undertaken, to establish the pathogenicity of the two species. No symptoms were observed on plants inoculated with C. gloeosporioides; however, leaf and stem lesions developed after inoculation with C. truncatum, which was reisolated from the diseased tissue, confirming it as the disease-causing agent. Preliminary management practices for the disease are proposed.