Role and Impact of Diseases caused by soil–borne Plant Pathogens in Reducing Productivity in Southern Australian Pasture Systems

Summary

The role and impact of diseases caused by soil-borne plant pathogens in reducing productivity in southern Australian pasture systems urgently needs defining. As a consequence, this report evaluates the research and extension articles published on diseases caused by soil-borne fungal and nematode pathogens of annual and perennial forage legume and grass pastures which are sown in south west, southern, and south eastern Australia and highlights those currently believed to adversely affect the growth and/or production of the affected plant species. It also includes some of the animal toxicoses from toxin producing soil-borne fungi which in their own right may or may not cause disease of the host species. A number of nematode and necrotrophic soil-borne pathogens have been associated with significant productivity decline and pose a serious threat to one or more annual or perennial forage legume or grass species to the extent that they require reseeding. At the current state of investigations the most important fungi associated with root disease in the most widely grown pasture legume, subterranean clover, appear to be, in order of importance, Phytophthora clandestina, Pythium irregulare, Aphanomyces eutichies, Rhizoctonia species and F. avenaceum. This report highlights the areas needing to be addressed if losses caused by soil-borne plant pathogens are to be reduced.