Isolation and Assay of the Toxic Metabolite(s) Produced by (Colletotrichm gloeosporioides) On (Jatropha curcas)

Anthracnose on Jatropha curcas leaves is caused by Colletotrichum gloeosporioides. On infected leaves, it is associated with a characteristic dark brown to black necrotic lesions that are irregularly shaped and appear on the lamina and center of the leaf and are surrounded by a yellow halo, which indicates a role played by toxic metabolites secreted by the pathogen. Six test plants which include jatropha, maize, cassava, melon, sorghum and cowpea were grown in five kg pots and arranged in a Completely Randomized Design. Pure culture of C. gloeosporioides was grown in a modified Richard’s B medium. Mycelia were harvested by filtration at 7 day intervals and discarded. The crude filtrates was assayed for biological activity on the test plants. These culture filtrates were also sprayed on noxious weeds namely: Ageratum conyzoides, Tridax procumbens, Larpotea aestuans, Eurphorbia hirta, Synedrella nodiflora, Desmodium scorpiurus and Eleusine indica. Chlorotic and necrotic symptoms were observed on plants inoculated with 35, 42, 49, 56, 63 and 70 day-old culture filtrates, but not on control plants. The results from this study suggest the presence of toxic metabolite(s) in the culture filtrates of C loeosporioides as symptoms induced by the filtrates on leaves were similar to those produced y the pathogen under the natural infection conditions.