بررسي علل گياهچه ميري برخي از نارون هاي چيني در گرگان

Investigation on casual agents of Damping-off on some of the Chinese elm seedlings in Gorgan

This research was carried out to find the casual agents of damping-off of some of the Chinese elm seedlings located at agricultural faculty of Gorgan University and to isolate its agents. In this order, some of the dried or semi-dried seedlings were transferred to laboratory in spring 2005. Roots, crowns and stems of seedlings were washed and disinfested in 0.5% NaGCI. 5-10 millimeter-pieces plated on PDA and incubated under standard conditions. Based on microscopic and macroscopic characters isolates belong to Fusarium spp. fungus. After purification of isolates on 2% WA with single spore method, those were identified based on the important morphological characters such as colony form and color, microconidia and macroconidia and formation of chlamydospore by valid keys. These 5 isolates identified as F. solani and F. oxysporum. Phathogenicity tests were performed by inoculation ISO± 25 milliliter of spore/chlamydospore suspension 3 x 10· (spore/ml) around of the root of the seedlings. This study is the first report of Fusarium solani and F. oxysporum as causal agents of damping-off of Chinese elm in Iran