Abstract
Dead twigs of unknown cause standing among healthy twigs with normal green leaves in the same bush of tea have been observed frequently in Taiwan since 1955. Macrophoma theicola was isolated from 102 of 104 diseased twigs collected from various cultivars at different locations. Three weeks after inoculation with wheat-oat grains colonized by M. theicola, more than 86% of inoculated twigs showed die-back symptoms similar to those observed in nature. Macrophoma theicola was reisolated from all of the experimentally infected twigs. All control twigs remained healthly during the experiment. Twigs inoculated with M. theicola grown on potato dextrose agar failed to show any disease symptoms. Macrophoma theicola thrived at relatively high temperature and endured low water potential. The fungus was able to grow about 0.3cm linearly in 2 days at 38C and in 5 days at -71 bars.
