sclerotinia stem rot (ssr), caused by sclerotinia sclerotiorum, is the most important diseases of canola (brassica napus) in iran. in order to study of the impact of ssr on canola yield, infection situation and yield of 80 fields in four different regions of golestan province (gorgan, ali abad, kalaleh and gonbad) in north of iran, was recorded during two growing seasons (2006 and 2007). ssr se...