Identification and Pathogenicity of Pythium Species on Cantaloupe in Khorasan Razavi Province of IRAN

In order to study the role of Pythium species associated with cantaloupe root and crown rot، samples were collected from infected fields in different areas of Khorasan Razavi province during 2009-2010. The Root pieces were washed and cultured on CMA-PARP medium. The pythium isolates were then purified by hyphal tip method and identified based on van der Plaats-Niterink mycological key. The pathogenic species were identified as Pythium aphanidermatum، P. ultimum var. ultimum، and P. deliense. The pathogenicity of isolates on cantaloupe seedlings was tested under greenhouse conditions by using wheat grain inoculum. The results indicated that P. aphanidermatum was the most prevalent species and was recovered in all the regions. P. ultimum was isolated from Neyshabour، Fariman and Mashhad whereas P. deliense was detected in Khaaf. This to our knowledge، is the first report on occurrence and distribution of Pythium species causing root and stem rot on cantaloupes in Khorasan province.