Investigation on agent conifer damping off in the forest nursery of Lakan

Damping off is one of the prevalent diseases in forest nurseries, which makes sever damages to conifer seedlings every year. Damping off caused to changes in color and curvature of seedling into puteal and become to seedling mortality. This study was executed in order to identify the causes of damping off in conifer seedlings in the nurseries of Lakan in Guilan province. For this purpose, the infected seedlings were collected and transferred to the laboratory for further research. After isolation and purifying the morphologic characteristics, the macroscopic and microscopic characteristics of the pathogenic agents were studied. The detected isolated pathogens were: Rhizoctonia solani Kuhn, Pythium sp., Fusarium solani (Mart.) Sacc., F. oxysporum Schlecht, F. semitectum Berk. & Rav. and Fusarium sp. The all symptoms of pathogens distinguished were similar to the primary contaminated seedling. The obtained results showed that the abundant of Pythiium sp. was higher than the other patogens in Lakan nursery. We can mention that, this is the first report of the presence of Fusarium semitectum var. majus at the pine trees in the Guilan province in Iran.