EPIDEMIOLOGY OF FUNGALLY-TRANSMITTED VIRUSES

Abstract. The recent spread of sugar‐beet rhizomania and barley yellow mosaic virus in Europe has stimulated fresh interest in plant viruses with soil‐borne fungal vectors. Although there are at least 20 such viruses, most of which cause diseases of important field crops, there are many gaps in our knowledge of their epidemiology because much research has concentrated exclusively on the viruses. The vectors are lower fungi that are obligate parasites of plant roots and are therefore difficult to study experimentally. Resting spores containing virus can survive indefinitely in soils but effects of rotation have not been greatly studied. There is no quantitative information relating inoculum levels of fungus and virus to disease development. Only limited information is available about inoculum distribution in soil and factors affecting its potency. The diseases are mostly dispersed by soil movement during agricultural operations but some features of disease distribution in infested fields await adequate explanation. Little is known about interactions with other micro‐organisms. Copyright © 1990, Wiley Blackwell. All rights reserved