Identification and Occurrence of Perfect Stage and Cultural and Morphological Variants of Colletotrichum gloeosporioides from Guava in Puerto Rico

Abstract

Two strains of Colletotrichum spp., one dark and one light, were isolated from diseased fruits of guava in Puerto Rico. The isolates differ in cultural appearance, physiologic characteristics, and size of conidia. The optimum temperature range for mycelial growth of the dark strain lies between 24° and 28° C. The optimum temperature range for the light strain lies between 28° and 32° C. The optimum pH range for both strains lie between 5 and 7. Perithecia were produced when the dark strain was crossed with the light strain, or grown alone in potato dextrose agar at 24° to 28° C. Perithecia obtained from both isolates were typical of Glomerella cingulata. Ascospore isolations consistently resulted in the recovery of typical C. gloeosporioides cultures. Although conidia produced by the dark strain are significantly longer than those of the light strain, their perithecia are indistinguishable. Both strains are identified as C. gloeosporioides, the conidial stage of G. cingulata. The formation of the sexual stage of C. gloeosporioides in vitro in Puerto Rico has not been reported hitherto.