BIOLOGICAL-CONTROL OF ROOT DISEASES WITH DSRNA BASED ON POPULATION-STRUCTURE OF PATHOGENS

Genetic individuals can be distinguished based on vegetative incompati bility in some fungi and are referred to as ''genet''. They compete fo r resources with each other, and competition may result in disease sup pression or decline, leaving a few fit genets. Double-stranded (ds) RN A of hypovirus origin, which infects healthy isolates through cytoplas mic contact and attenuates virulence, could promote decline where the population of pathogen is composed of a very few predominant genets. P revious studies on chestnut blight demonstrated that the spread of dsR NA was negatively correlated with the diversity in vegetative incompat ibility in the population of the pathogen, Cryphonectria parasitica. I considered that this finding applies to some diseases which remain di fficult to control chemically, culturally, and, of course, biologicall y. Helocobasidium mompa and Rosellinia necatrix, the root rot pathogen s of perennial crops, may be biocontrolled by dsRNA due to their simpl e population structure, their mode of epidemiology, and the high value of their individual host plants. Collaborative studies by concerned s cientists are necessary to identify such viruses and to develop effect ive inoculation methods of indigenous genets with hypoviruses.