Evaluation of relative resistance of some walnut genotypes and cultivars to the anthracnose disease.
2008
Dastjerdi, Ra`na | Haq Juyan, Ruh Al-Lah | Ne`mat Zadeh, Faramarz | Hassani, Darab
Anthracnose, caused by Gnomonia leptostyla (Fr.) Ces.and de Not. ( imperfect state: Marssonina juglandis ( Lib.) Magn. ), is the most serious foliar disease of black walnut. This research is designed to determine relative resistance to Gnomonia leptostyla of 11 varieties based on factoriel design on the basis of Completely Randomized Block.In order to retain of requirement plant material, grafting of walnut genotypes was done using Omega Mashine in the greenhouse. After producing inoculla, grafted plants were inoculated by a 105 spore per ml suspension.The results showed that germination of spores was higher on the upper side of the leaves. The first symptoms of infection were seen on Z60 and Hartley. The acervuli were produced first on K72 genotype about 27 days after inoculation. Two month after inoculation, evaluation was done in each plants by determination of the number and the mean diameter of spots.There were a significant differences among the genotypes and cultivars in susceptibility. The average infection percent on the Z60 and Hartley was higher and Vina, Rounde de montignac,Franguett, Serr, Lara and Pedro showed the least infection.. Meanwhile, there was collected 45 isolates of the fungus from different walnut planting areas in Iran. There were a significant differences among the pathogenicity of the isolates. The results indicate also that, there were a significant correlations between the number of spots and the leaflet specific fresh weight(LSFW), so the upper leaflets on the leaves, and especially the terminal ones, with the highest LSFW were the most susceptibles to the disease.
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