The detection of antifungal substances before and after infection of beans (Vicia faba L.) by Botrytis spp.

SUMMARY Previous work showed that germ‐tube growth of Botrytis cinerea, but not of B. fabae, is inhibited several hours after germination on the leaves. This study concerns the detection of substances in leaves and pods which could explain the different responses of the two fungi. Ether and methanol extracts of leaf surfaces were not inhibitory to either fungus. Drops of water which were incubated for periods up to 48 hr. on healthy leaf surfaces became slightly inhibitory to germ‐tube growth of both fungi. However, drops of water containing spores of B. cinerea became highly inhibitory after incubation on surfaces of leaves or in seed cavities of pods for 72 or 24 hr. respectively. Drops containing spores of B. fabae and water controls became stimulatory to test spores after incubation for 24 hr. in pods but slightly inhibitory after 72 hr. on leaves. The inhibitory substances were partially extracted from collected drops into petroleum ether. Substances soluble in petroleum ether extracted from the endocarp of pods were highly inhibitory to test spores 24 hr. after infection by B. cinerea but stimulatory before infection or 24 hr. after infection by B. fabae.