Abstract

Hymenachne amplexicaulis, native to Central and South America, is an aggressive weed in aquatic ecosystems in Australia, and was introduced as a pasture plant in the 1970s. It is now one of the 20 species listed as weeds of national significance. During a search for potential biocontrol agents of this weed in the Brazilian 'Pantanal do Mato Grosso', near Corumbá, two previously unrecorded fungal parasites, Curvularia lunata and Phyllachora sp. were found associated with a leaf spot and tar spot of H. amplexicaulis, respectively. A limited host range test demonstrated that C. lunata is weakly pathogenic on maize, lemon grass and infects gladiolus and Bermuda grass. Phyllachora spp. are biotrophic parasites which are seldom pathogenic. Neither fungus is deemed useful as classical biocontrol agents.