بررسي بيماري لكه سياه (آنتراكنوز) گردو در مناطق شمال غرب كشور

Study on walnut anthracnose disease at the northwest of Iran

Walnut black spot disease (Anthracnose) has been distributed in northwest of Iran especially in Qazvin province. Recent years (from 1998 to 2001), various regions including Quzvin, Zanjan, Hamedan and East Azarbayjan provinces were surveyed. Suspected samples of leaves, fruits and foliage have been collected from studied areas. Then they were cultured in PDA, CMA and NA media after surface sterilization with sodium hypochlorite. Morphological characteristics and asexual reproduction of pathogen showed that the causal agent of this fungal disease was fungi named Marssonina Julandis which isolated from infected samples specially leaves. The disease was severe in all studied areas and when it was rainy, and relative humidity was high (80%) so that the fungal pathogen hadepidemic population, In this case there was main defoliation in some walnut trees. Investigation showed that the collecting and burning of infected leaves and fruits under trees were reduced severity of disease. On the other hand, there was a resistant variety around the Qazvin called "Alamoty" which had not any Anthracnose infection in natural conditions. The result of experimental test by inoculation of different walnut clones byl0^5 spores suspension in glasshouse conditions has also indicated that the "Alamoty" clone was more resistant than others to Anthracnose disease.