Screening of Jatropha curcas genotypes to anthracnose caused by Colletotrichum gloeosporioides.

Anthracnose caused by Colletotrichum gloeosporioides is an important physic nut (Jatropha curcas) disease causing damages on leaves, stems and fruits and consequently a decrease in seed quantity and quality. Physic nut is a native plant of Central America that has gained international attention due to its potential as biodiesel crop. However despite its highest relevance, studies concerning the response of different Jatropha genotypes to infection with this disease are very limited. The main objective of this study is the evaluation of susceptibility of 38 Jatropha curcas genotypes from a worldwide germplasm collection to Colletotrichum gloeosporioides. A simple method using wounded detached leaves inoculated with a 5-mm mycelia plug was used. Observations (lesion diameter and % of infection) were made after 3 and 7 days under controlled conditions (25 degrees C and 85% RH). Results showed significantly differences (P < or = 0.001) in both percentage of infection and lesion diameter among the tested accessions. Two genotypes from Brazil and Cape Verde, presented no lesions after 7 days of treatment, while the others presented between 67 and 100% of infection. Lesion diameter showed an increase with time of incubation and proved to be a useful tool for evaluation of plant susceptibility.