Various concentrations of 42 dyes, alkaloids, plant-growth regulators, and miscellaneous chemicals were tested as substitutes for rose bengal in peptone–dextrose–streptomycin agar for isolating soil fungi by the dilution-plate method. Most of the chemicals did not compare favorably with rose bengal, but a plant growth retardant 2,4-dichlorobenzyltributylphosfonium chloride (phosfon) used at 500 μg/ml significantly increased numbers of fungal colonies per plate and suppressed fast-growing fungi. The value of phosfon persisted even in the presence of gibrel, which alone induced rapid overgrowth of plates by Trichoderma and the Mucoraceae.
Fungi obtained on various media from soil under banana trees near Logos in Nigeria