Abstract
It was previously reported that shoot blight of the tea plant, Camellia sinensis (L.) O. Kuntze, which occurred extensively in Japan was caused by the tea gray blight fungus, Pestalotia longiseta. It was anticipated that the increase in the number of leaves affected with tea gray blight after mechanical plucking of new shoots in a certain flush might bring about a linear increase in the number of shoots showing shoot blight in the next flush. However such a phenomenon did not necessarily occur, and occasionally the number of affected shoots decreased with the increase in the number of diseased leaves. In this report, it was indicated that the tea brown blight fungus, Glomerella cingulata, was able to suppress the occurrence of shoot blight. The simultaneous inoculation with P. longiseta and G. cingulata to new shoots of cv. Yabukita, which was very susceptible to P. longiseta but resistant to G. cingulata, reduced the number of shoots showing shoot blight. Pre- and post-inoculation with G. cingulata also resulted in the reduction of the number of affected shoots. Therefore, in the tea gardens, as tea gray blight caused by P. longiseta occurred more greatly, density of G. cingulata became higher concurrently. Increased G. cingulata suppressed the occurrence of shoot blight caused by P. longiseta. That was why there was not always linear correlation between the number of leaves affected with gray blight and the number of shoots showing shoot blight.
