EFFECT OF INOCULATION OF POTATO-TUBER DISKS BY NONPATHOGENIC FUSARIA ON FUSARIUM TUBER ROT

The interaction between non-pathogenic fusaria of potato tuber discs on disease incidence causes by Fusarium oxysporum was studied. Blasticidin-S resistant mutant of the pathogen, Fusarium oxysporum L sp. lycopersici and Fusarium roseum were choosen. Discs individually inoculated by such non pathogenic fungi were inoculated by the pathogen at different intervals (i.e. 0, 3, 6 and 9 h) from inoculation by the non-pathogens. Phytoalexin rishitin was determined as evidence for enhancement of defence reaction. Data obtained indicated that Blasticidin-S resistant mutant and F. lycopersici (closely related to the pathogen) completely reduced disease incidence especially when inoculation by the pathogen was carried out 3 h after inoculation by the non patoghens. Fusarium roseum slightly reduced disease incidence even when the pathogen was inoculated 9 ha after inoculation by the non-pathogen. The obtained data led to postulate that the compounds accumulate in potato tuber in respons to infection by non-pathogens play a secondary role in limitation the challenge. The prime factor determins the state of interaction between pathogenic fusaria and potato tuber may be the recognition site between host and pathogen.