Grouping of mango anthracnose fungus in Taiwan.
Weng F. Y., Chuang T. Y.
Author Affiliation: Department of Plant Pathology and Entomology, National Taiwan University, Taipei, Taiwan.
Plant Protection Bulletin (Taipei) 37 : 295-309
Abstract : Among 444 isolates of anthracnose fungi from lesions on fruit and leaves of 5 different cultivars grown in Taiwan, 363 were identified as Colletotrichum gloeosporioides [Glomerella cingulata] and 81 (only on Irwin and Toswaei) as C. acutatum. All the cultures were derived from single conidia and grown on PDA at 26°C with a 12h photoperiod for 7 d. With the exception of the Radio type cultures of both species, the isolates were grouped on the basis of colony appearance, mycelial morphology and reproductive structures. Numerical classification of the morphological characteristics was performed using the NTSYS-pc Analysis system. The dissimilarity matrices were generated for each data set by the SAHN program. Each association matrix was subject to a hierarchical agglomerative polythetic clustering, based on the Flexible UPGMA (Unweighted Pair Group Arithmetic Averaging) strategy. The resulting hierarchies were plotted using dendrograms. The isolates of G. cingulata were derived into 7 groups by these procedures. Groups I and II predominated in populations of the fungus. All isolates of Group IV were obtained from cv. Irwin and all of Group VII from Haden. Pathogenicity tests showed no significant differences among groups but there were differences among isolates in the same group. Among the cultivars tested, Toswaei and Keitt were the most susceptible to anthracnose and Kinghuang was the most resistant. The opt. temp. for mycelial growth of both species was 28° but C. acutatum had a slower growth rate than G. cingulata.