Isolated fungi from hazelnut, their damage and economic importance in Guilan province

Cultivated areas of hazelnut is more than 12000 hectares mainly concentrated in Eshkaverat (Rudsar) in Guilan province. In recent years, a survey was carried out on the occurrence and severity of fungi causing diseases on hazelnut in different growth stages in field plots and stored hazelnuts in different aeras of Guilan province, including Rudsar, Lahijan, Astara and Somehsara. Samples were taken from the hazelnut trees showing disease symptoms and cultured in PDA, CMA, MA and WA media for isolation of the causing agents. Pathogenicity of extracted fungi was confirmed by inoculation of single spore and hyphal tip cultures to hazelnut seedlings or branches and leaves of hazelnut trees in growth chamber. To find out the infection rate of leaf spot Mamianiella coryli disease as it is an important pathogen in the region, four gardens were selected in Zeyaz and Aghozbon Kandsar (Eshkaverat) and from each garden 20 trees and from each tree 400 leaves were collected randomly and infection rate was determined by using a grading system. In this investigation, 16 fungi isolates were collected and identified as follow: Alternaria alternata, Mamianiella coryli, Phyllactinia corylea, Pestalotiopsis macrospora, Diplodia theabrome and Colletotrichum gloeosporioides were identified as pathogens on leaves and stems and fungi including Phomopsis sp., Fusarium semitectum, Fusarium anthophilum and Verticillium sp. were isolated from crown and roots of hazelnut trees. The fungi, Rhizopus sp., Aspergillus flavus, Aspergillus sp., Penicillium sp., Trichothecium sp. and Cladosporium cladosporiodes were isolated from hazelnut fruits in storages. The preliminary studies of distribution and damage of Mamianiella coryli as causing agent of sudden leaf defoliation of hazelnut trees in Aghozbon Kandsar (Eshkaverat) indicated the damage rate of the disease as 20% of the leaf surface.