Kritzman, G.
Netzer, D., Div. of Plant Pathology, ARO, The Volcani Center, Bet Dagan, Israel
The population of Botrytis allii in either naturally or artificially infested soils was selectively measured by the soil dilution plate count procedure on a developed synthetic medium supplemented with tannic acid, fungicides, antibiotics and Cu++ions. Conversion of tannic acid into a dark brown pigment was related to the activity of extracellular polyphenoloxidase produced by the fungus. Thus, brown-pigmented colonies were recognized as Botrytis spp. The same medium was used for detecting the presence of the fungus on onion seed. © 1978 Springer Science + Business Media B.V.