EVALUATION OF RELATIVE RESISTANCE OF SIX SUNFLOWER CULTIVARS TO Alternaria alternata

Leaf spot disease is one of the most destructive foliar diseases of sunflower. The use of resistant genotypes is potentially one of the most economical means for the disease control. A greenhouse assay was used to evaluate resistance of six sunflower cultivars, namely Dorsefid, Ghalami, Pestei, Master-op, Azargol, and Euroflor against three isolates of A. alternata . The isolates showed significant differences in pathogenicity. The reactions of cultivars to fungal isolates were different; however, none of the cultivars showed high levels of resistance. This is the first study on the evaluation of partial resistance of some of the sunflower cultivars to the Alternaria leaf spot disease in Iran.