Evaluation Of Relative Resistance Of Rapeseed Cultivars And Lines To Sclerotinia Stem Rot And Isolation Of The Causal Agent

Sclerotinia stem rot of rapeseed caused by Sclerotinia sclerotiorum (Lib.) DeBary is considered as one of the most important diseases of this crop in the north of Iran. Use of resistance, because of the compatibility with the other premonitoring and control ways, is paramountly important in integrated pest management of the disease. In this investigation, reactions of four lines and 21 cultivars of rapeseed were evaluated using the fungal mycelium coated wheat seeds method, in a single lattice design (5 x 5) at Bayekola Research Station of Neka (Mazandaran). Reactions were recorded before the harvesting time, on the basis of macroscopic symptoms. To assess relative resistance of genotypes quantitatively, a rating system of 1 (resistant) to 5 (very susceptible) was introduced and the disease index (DI) on the basis of mean rating score for each genotype was calculated. The results indicated that there were significant differences among the genotypes at 1% level of all tested genotypes, Foseto and Ebony had the highest and lowest resistance to the disease, respectively.