Development of a selective myclobutanil agar (MBA) medium for the isolation of Fusarium species from asparagus fields

A new selective myclobutanil agar medium for the detection of Fusarium species is proposed. Ten media formulations based on various selective agents (pentachloronitrobenzene (PCNB). Rose Bengal, malachite green, sodium hypochlorite, captan, benomyl, chlorotalonil, myclobutanil, thiram, and cupric sulfate) were compared. First, mycelium growth and colony appearance of Alternaria alternata, Aspergillus flavus, Cladosporium cladosporioides, Epicoccum nigrum, Fusarium sp., Fusarium solani. Fusarium moniliforme, Fusarium oxysporum f.sp. dianthi. Penicillium sp., and Trichoderma viride isolates were compared. Second, the ability of the different media to isolate and enumerate fusaria from asparagus fields was evaluated. The myclobutanil-based medium showed the highest selectivity to Fusarium spp. growth but required a slightly longer incubation time (> 5 d) than peptone-pentachloronitrobenzene-based agar (PPA) (< 5 d). PPA allowed a faster fusaria growth but also permitted the growth of other moulds. The other media were less selective and did not allow to isolate fusaria or to differentiate them from other growing fungi.