Abstract

CHAKWIYA, Alinesi; VAN DER LINDE, Elna J.  and  KORSTEN, Lise. In vitro sensitivity testing of Cladobotryum mycophilum to carbendazim and prochloraz manganese. S. Afr. j. sci. [online]. 2015, vol.111, n.11-12, pp.1-7. ISSN 1996-7489.  http://dx.doi.org/10.17159/sajs.2015/20140408.

Limited information of fungicide efficacy on cultivated mushrooms and resistance development potential is available. Minor crop industries in general have a smaller arsenal of protectants to rely on and the likelihood of resistance build-up is of greater concern. This study focused on Cladobotryum mycophilum's sensitivity to carbendazim and prochloraz manganese following recent reports on decreased efficacy of both fungicides. The median effective dose (ED₅₀) values for carbendazim ranged between 0.02 mg/L and 4.31 mg/L with 60% of the South African isolates being moderately resistant. The highest resistance factor for carbendazim was 215. Prochloraz manganese ED₅₀ values varied from 0.00001 mg/L to 0.55 mg/L. A significant difference in mean ED₅₀ values for both fungicides tested was observed. Using cluster analysis, no discrimination of isolates previously exposed and unexposed to prochloraz manganese was observed. A wide range of differences in ED₅₀ values indicated moderate resistance to carbendazim and high sensitivity to prochloraz manganese among isolates under investigation. Discriminant analysis indicated significant differences between clusters contributed by one or a few variables. This study provided evidence that prochloraz manganese remains highly fungitoxic to C. mycophilum. However, prochloraz manganese is to be used in a disease management strategy in combination with strict farm hygiene management strategies to retain product efficacy and ensure crop protection.

Keywords : Agaricus bisporus; cobweb disease; fungicide effectiveness; fungicide resistance; fungicolous fungi.

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