Response of the mushroom pathogen Cladobotryum mycophilum to prochloraz and metrafenone fungicides and Streptomyces flavovirens actinobacteria

Abstract

After an outbreak of cobweb disease of cultivated button mushroom in Serbia in 2003, the isolated fungal pathogen was initially identified as Cladobotryum dendroides (teleomorph Hypomyces rosellus) based on morpho-physiological traits. Molecular analysis indicated re-classification of two strains (isolated in 2004 and 2007) as Cladobotryum mycophilum (teleomorph Hypomyces odoratus). However, subsequent analysis of further five strains (isolated over the period 2003-2010) within the frames of the present study, also confirmed their identification as the exclusive cobweb causal agent C. mycophilum. After artificial inoculation, the symptoms observed on harvested and growing mushrooms were consistent with the appearance of cobweb disease. Pathogen sensitivity to fungicides was estimated by probit analyses. Fungicide susceptibility tests showed that C. mycophilum strains were highly sensitive both to prochloraz (ED₅₀<0.087 µg mL⁻¹) and the newly introduced metrafenone (ED₅₀<0.15 µg mL⁻¹). Furthermore, the growth of all examined strains of C. mycophilum was significantly inhibited by the indigenous actinobacterial strain Streptomyces flavovirens A06. A dual culture assay showed after 72 h that the percentage of radial growth inhibition of the pathogen ranged from 22.38 to 55.73%. Our findings suggest that the antagonistic S. flavovirens A06 might be a potential candidate for controlling the cobweb disease of cultivated button mushroom.

Keywords:

• Cobweb disease
• Cladobotruym mycophilum
• button mushroom
• Agaricus bisporus
• fungicide sensitivity test

Disclosure statement

We confirm that the research described in the manuscript is an original work of the authors that has not been previously published, in whole or in part, and that it is not under consideration by any other journal. Non-digital data supporting this study were curated at the Institute of Pesticides and Environmental Protection, Belgrade, Serbia.

Additional information

Funding

The study was funded by the Science Fund of the Republic of Serbia under Grant for Scientific Research Organisations No. 451-03-68/2022-14/200214; the Hungarian Government and the European Union under Grant GINOP-2.2.1-15-2016-00006, Széchenyi 2020 Programme; and the National Research, Development and Innovation Office under Grant NKFI K-116475.