New Sources of Resistance in Vicia faba to Chocolate Spot Caused by Botrytis fabae

Abstract

A two-cycle screening technique was used to evaluate 253 faba bean germ plasm accessions for resistance to chocolate spot. In the first cycle in 1985, faba bean accessions were exposed to a mixture of 20 isolates of Botrytis fabae collected from a wide range of naturally infected leaves of local susceptible cultivars grown in major faba bean production regions in Syria. Some of the resistant accessions detected in 1985 developed a few coalesced sporulating lesions. To subject resistant materials to a rigorous evaluation, 20 isolates of B. fabae obtained from such lesions were used in a second screening cycle in 1986 to inoculate progenies of the resistant accessions detected the previous season. Of the 253 accessions, 14 new, potentially useful sources of resistance to a wide range of isolates of the pathogen were identified.