A Selective Medium for the Recovery and Enumeration of Fomitopsis meliae, Causing Lemon Canker and Brown Wood Rot

Abstract

A selective medium was developed for the isolation and quantification of Fomitopsis meliae (FMS medium), the causal agent of lemon canker and brown wood rot, from plants, soil, and air. The optimal concentration and combination of fungicides and antibiotics was evaluated to determine the most selective condition for growing F. meliae. The resultant composition of the FMS medium per liter (pH 3.5) was 16 mg of thiophanate-methyl, 8 mg of dichloran, 5 mg of 2-phenylphenol, 100 mg of fluopyram, 0.5 mg of fludioxonil, 100 mg of chloramphenicol, 100 mg of streptomycin, 15 g of malt extract, 2.5 g of mycological peptone, and 15 g of agar. The fungus was successfully isolated and enumerated from air, soil, and plant tissues using FMS medium. Furthermore, FMS medium almost completely inhibited the growth of other plant-pathogenic fungi and soil and air saprophytes. This selectivity was high enough to estimate spore inoculum of F. meliae in an air sample or as a spore-trapping device in commercial lemon orchards. FMS medium will be useful for studying epidemiology and management of F. meliae.