Fusicladium veronicae (Batista), comb. nov., causing Brown Leaf Blight of Parahebe species

Abstract

In Victoria, continuing surveys of leaf pathogens of native Australian plants of value in ornamental horticulture have yielded a wide range of new or poorly known microfungi. Two of these have been formally described, Tandonella oleariae on Olearia spp. (Sutton and Pascoe 1987) and Pseudocercospora correae on Correa spp. (Sutton et al. 1987). A species of dematiaceous hyphomycete causing a severe blight on leaves of Parahebe perfoliata (R.Br.) B. Briggs & Ehrend. has been repeatedly collected from the Plant Research Institute Gardens, Burnley and elsewhere in Victoria. So devastating is the disease that few nurserymen have persisted in retaining the plant as a commercially viable option. The same fungus has also been found on leaves of Parahebe formosa where the symptoms are much less severe. Attempts to determine the identity of the causal organism show that few fungi have been reported from Parahebe. One of these, Ramalia veronicae Batista (1957), was described from Veronica derwentiae Littley (a synonym of Parahebe derwentiana (Andr.) Briggs & Ehrend.) as a hyperparasite of Parasterina veronicae (Lib.) Bat. and Asteromella veronicae (Desm.) Arn. Examination of the holotype of R. veronicae (DAR 3568) shows that it is not a hyperparasite on the other fungi but occurs mixed with them on stems, petioles and leaves of the host. R. veronicae is conspecific with the fungus causing disease on Parahebe perfoliata and P. formosa and thus provides a binomial for this fungus.