Determination of Bioactivity of Avirulent Fusarium oxysporum to Control Crown Rot Agent Fusarium culmorum on Some Bread Wheat Varieties

F.culmorum is one of the most important fungal pathogen causing crown rot in rainfed wheat cropping areas worldwide. In this study the effects of avirulent Fusarium oxysporum applying (1x10^6 spor/ml^-1) on the crown rot disease of wheat plants caused by F.culmorum were studied in 2008 at greenhouse conditions. In this study carried out using tolerant variety 2-49 and sensitive variety Bezostaya-1, while F.culmorum was inoculated on seed, soil and seedling(1x10^6 spor/ml^-1), F.oxysporum was applied to seed and leaf. At the end of this study, according to statistically analysis in terms of disease intensity F.culmorum, variety and variety x F.culmorum interaction were found significant statically at the level of 1%. F.oxysporum didn’t have the effect on the pathogenicity, the changing on the disease intensity was caused by F.culmorum applying. While the average disease intensity on Bezostaya-1 was 35.38%, it was 13.35% on 2-49 variety. Applying methods of F.culmorum was found significant statically at the level of 1%; while seed applying (34.02%) and soil applying (35.49%) placed in the same group, seedling applying (34.02%) and control applying (35.49%) placed in different groups statically. In terms of coleoptiles’ score and the number of leaves with necrosis, variety, F.culmorum applying, Variety x F.culmorum interaction was found significant, and F.oxysporum was not found insignificant statically. In terms of the number of leaves with necrosis, F.culmorum x F.oxysporum interaction was found significant statically at the level of 5%. F.culmorum applying (x) and F.oxysporum applying (y) interactions were ranked; Seed, Seedling (3.95) Leaf, Seedling (3.60) Leaf, Soil (3.10) Seed, Leaf (2.65) Seed, Seed (2.45) Leaf, Seed (2.10) Control (0) respectively. As a result, avirülentF.oxysporum isolate didn’t have any changing effect on the disease severity of used virulent F.culmorum isolate.