Chocolate spot disease caused byBotrytis fabae is a major problem that limits faba bean production in Egypt.The in vitro antifungal activity of chitosan and its ability to elicit defense responses in two faba bean cultivars Giza 416 (resistant) and Giza 40 (susceptible) against this fungus were evaluated.Seven isolates of B. fabae were cleaned from infected leaves.All isolates were pathogenic to G...