عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In order to identify and evaluate the pathogenicity of Fusarium species associated with root and crown rot of contalupe and melon, several fields in different regions of Khorasan including Mashhad, Kashmar, Mahvelat, Khaff, Torbat Jam, Fariman, Neyshabour and Sarakhs were sampled during 2009-2010 growing season. After disinfection with sodium hypochlorite (1%), pieces of infected tissues were cultured on potato dextrose agar (PDA) medium. Grown fungal isolates were then purified and were identified based on their morphological characteristics as different Fusarium species. To test pathogenicity of Fusarium isolates, 12-day-old cantaloupe seedlings grown in the green house were inoculated with fungal spore suspension (106/ ml) by root dip inoculation method. The disease symptoms appeared after 4- 21 days. To fulfill Koch’s (pathogenicity) postulates, disease causal agents were re-isolated from the symptomatic plants. The pathogenic isolates were identified as F. solani, F. oxysporum and F. equiseti of which the first species was dominant. The results also showed that F. equiseti and F. acuminatum were mostly isolated from mature plants while F. solani and F. oxysporum were present in all growth stages of plants (seedling up to fruit stages). Results of distribution studies showed that these species were widely spread throughout the province and apparently their distribution is not affected by weather conditions. According to our findings, the above-mentioned Fusarium species seem to be the causal agents of root and crown rot of cantaloupe and melon and consequent wilting and vine decline which is an important disease in arid and semiarid areas.