Occurrence and pathogenicity of various pathogenic fungi on cucurbits from Kermanshah province, Iran.

Abstract

Cucurbits (Cucurbitaceae) are among the important plant families providing edible products to humans worldwide. It is known fact that various pathogenic fungi can attack the plants and cause diseases and resultantly yield losses. The aim of this study was to isolate and identify the plant pathogenic fungi from cucurbit plants and to evaluate their pathogenicity on cucurbits. A total of 101 cucurbit samples infected with diseases were collected from different places in Kermanshah Province, Iran. From these samples 101 strains of various pathogenic fungi were isolated and identified through morphological characters. All strains were belongs to Fusarium oxysporum, Macrophomina phaseolina, Phytophthora melonis, Phytophthora drechsleri, Pythium aphanidermatum and two morphotypes of Fusarium solani species complex (FSSC). P. aphanidermatum and Phytophthora sp. strains were recovered from the samples collected from irrigated field, while Fusarium and M. phaseolina strains from rain fed field. All these pathogenic fungi were evaluated to study their pathogenicity on cucumber (Cucumis sativum) and honeydew melon (Cucumis melo). P. melonis, P. drechsleri, F. oxysporum and P. aphanidermatum caused the damping off within 10 - 20 days on both plants tested. The stem rot symptoms were observed on the 7th day after inoculation of F. solani and M. phaseolina on both plants tested. The inoculated fungi were re-isolated from the diseased plants to prove the Koch’s postulates. This is the first comprehensive report on identity and distribution of major plant pathogenic fungi causing root and stem rots on cucurbits in west of Iran. Key words: Root and stem rot, pathogenicity, cucurbits, Iran.