Abstract
Eight isolates of the Fusicoccum anamorph of Botryosphaeria ribis (six from Melaleuca quinquenervia; two from Rhizophora mangle) were obtained from South Florida. Morphological characteristics of these isolates were studied on various culture media and excised leaves and stems of M. quinquenervia ramets. Mycelial morphology, sporulation attributes, dimension of conidiomata, and growth rate varied among isolates. Conidiophores were short and hyaline with a bulbous base arising from the lining of the stromatal locules. Fresh macroconidia were fusiform, truncate at the base, obtuse at the apex, hyaline, aseptate, but some of them developed 1–3 septa when retained in pycnidia on aged and dried culture media or germinated in water under coverslips. Regardless of septation, 1–5 germ tubes were produced from the polar as well as the lateral sides of conidia. Microconidia were rarely produced by most isolates. Microconidia did not germinate. The percentage of macroconidia germinating within 4–8 h was greatest at 25–35°C, was rare or absent at 5°C, and viability was lost at 45°C. The teleomorph stage was not observed on any growth media regardless of incubation conditions. These morphological characteristics support the characterization of the isolates as the Fusicoccum anamorph of B. ribis; also, many characteristics overlap with reported characteristics of the Fusicoccum and Dothiorella anamorphs of B. dothidea.