شناسايي قارچ هاي عامل زردي و خشكيدگي گياه چمن در شهر گرگان

Identification of fungi causal agents of yellow and decay of Lawn in the Gorgan city

In order to determine the fungi associated with decaying rot, crown and leaf of lawn in different parts of the Gorgan city, 34 samples were collected at four season of 2001-2. For this purpose, pieces of decaying and discolored parts of the root, foot and leaf were surface sterilized with commercial sodium hypochlorite (0.5%) for 1-2 minutes, and cultured on an acid and non acidic PDA and MA media. Isolates were obtained and divided into 4 groups, on the basis of morphological characteristic identified. Then pathogenicity tests were carried out by spraying 10 ml/sp spore of each pathogen inoculation on seeding lawn in greenhouse. The results showed that, 4 species were associated with the disease, and among them F. culmorunr was the most frequent (25 cases), which is considered to be the main incitant of crown lawns. Bipolaris .spicifera and Alternaria alternata were the most frequent (17 and 22 cases respectively), which are the cause of Brown spot of leaves and some necrotic of foot. Also, Rhizoctonia solani with the Lowest frequency 13 cases of isolation caused foot canker and drying rot. The results indicated that the pathogenic associated with moisture stress.