1998 Volume 39 Issue 2 Article ID: jjom.H09-35
Grayish and reddish fungal isolates were obtained from bitter rot apple fruits in Ehime Pref. and in Chiba and Niigata Pref., respectively. The former isolates were morphologically intermediate between Glomerella cingulata and Colletotrichum acutatum. As a result of comparison with C. acutatum and G. cingulata isolates from bitter rot apples, both types of isolates were identified as C. acutatum on the basis of conidial and appressorial morphology, mycelial growth speed and sensitivity to benomyl. This is the first report on apple bitter rot caused by a grayish colony form of C. acutatum in Japan. Vigorous acervular formation was observed on lesions produced by inoculation with C. acutatum. But few acervuli were produced on apples inoculated with G. cingulata, though the latter species developed lesions faster than the former. It was demonstrated by inoculation with various isolates of both species to apples that 13 host plant species of C. acutatum and 9 of G. cingulata were potential hosts of infection sources of the apple bitter rot.
