In vitro sensitivity of Verticillium fungicola to selected fungicides.

Twenty isolates of Verticillium fungicola var. fungicola collected from diseased fruit-bodies of Agaricus bisporus from prochloraz-treated crops, were exposed to a range of concentrations of six chemicals (benomyl, chlorothalonil, formaldehyde, iprodione, prochloraz-Mn-complex and prochloraz + carbendazim) in vitro. EC(50) values were determined for each fungus-fungicide combination. All isolates were more sensitive to prochloraz-Mn-complex (EC(50) values less than 5 mg 1(-1)) than to the remainder fungicides, and only seven isolates were moderately sensitive (EC(50) values between 5 and 50 mg 1(-1)) to prochloraz + carbendazim. All isolates were moderately sensitive to formaldehyde, whereas the majority of isolates were very resistant to the other three fungicides (benomyl, chlorothalonil and iprodione).