SPECIES OF MYCOSPHAERELLA AND THEIR ANAMORPHS ASSOCIATED WITH LEAF-BLOTCH-DISEASE OF EUCALYPTUS IN SOUTH-AFRICA

Mycosphaerella leaf blotch is a serious disease of Eucalyptus nitens a nd also occurs on several other Eucalyptus spp. in South Africa. The a im of the present study was to characterize the variation observed amo ng South African Mycosphaerella strains obtained from eucalypts. Earli er studies had suggested that only one species, M. molleriana, occurre d on eucalypts in South Africa. Contrary to these reports M. mollerian a was not found, but five new species of Mycosphaerella were collected and are described here. The name M. juvenis is proposed for the speci es commonly associated with leaf spots on juvenile leaves of E. nitens . Because its cercosporoid anamorph state could not be suitably accomm odated in Pseudocercospora, a new genus Uwebraunia is introduced for i t, and also for the anamorphs of two other new species, M. ellipsoidea and M. lateralis, occurring on E. cladocalyx and E. grandis x saligna , respectively. Mycosphaerella crystallina with a Pseudocercospora ana morph is described as a new species from leaves of E. bicostata. A Pse udocercospora sp. associated with spermogonia of an undescribed Mycosp haerella sp., is compared with known species of the genus from eucalyp ts, and described as P. epispermogoniana. Mycosphaerella marksii, rece ntly described from eucalypts in Australia, is also reported from Sout h Africa for the first time. A key to the species of Mycosphaerella pr esently known from Eucalyptus is also provided.