Conidial formation of Discula theae-sinensis on fallen diseased tea leaves

Abstract

Anthracnose caused by Discula theae-sinensis (I. Miyake) Moriwaki & Toy. Sato is the most serious disease of tea [Camellia sinensis (L.) Kuntze] in Japan. The pathogen retains its ability to form conidia on lesions on tea leaves that remained on tea plants for a long period. In this study, we examined conidial formation on diseased leaves that had fallen onto the ground. In the trial that began in June, conidial formation fell below the detection limit after 4 weeks. In contrast, in the trial that began in October, conidial formation was still observed in April. These results indicate that fallen leaves play only a minor role as infection sources during the tea growing season, but may serve as overwintering infection sources. Although diseased leaves remaining on the tree are regarded as the main infection sources, the potential contribution of fallen diseased leaves should also be considered.