Effective Control Strategies for Dry Bubble Disease in Button Mushrooms

A new research study published in BMC Microbiology provides critical insights into controlling dry bubble disease—one of the most damaging fungal threats to commercial button mushroom (Agaricus bisporus) production. The pathogen Lecanicillium fungicola can cause severe deformation, spotting, and yield loss, making it a major economic concern for mushroom growers worldwide. With the withdrawal of prochloraz in the European Union, growers now depend on a single approved fungicide, metrafenone. At the same time, the mushroom industry has been seeking sustainable alternatives such as biological control agents. This study evaluated both chemical and Bacillus-based biocontrol treatments under realistic crop-trial conditions, while also determining the optimal inoculum level for experimental disease assessment.

Key Findings from the Study

The researchers tested metrafenone, two Bacillus velezensis strains (QST 713 and Kos), and salting strategies across three independent crop trials. They demonstrated that an inoculation rate of 1 × 10⁴ conidia/m² most closely mimics on-farm infection levels and produces measurable but manageable disease pressure.

At this inoculum level:

Metrafenone achieved 96% efficacy, making it the most effective treatment.
Bacillus velezensis QST 713 reduced disease by 86%.
Bacillus velezensis Kos showed 74% efficacy.
Salting treatments suppressed disease by 73%, confirming its value as a simple IPM practice.

The study also confirms that extremely high inoculation levels (1 × 10⁶ conidia/m²) overwhelm both fungicide and biocontrol treatments, leading to severe yield loss—conditions unlikely to represent well-managed farms.

Why This Matters for the Mushroom Industry

These findings provide concrete, evidence-based guidance for growers navigating disease management under restricted fungicide availability. The results show that integrating early detection, salting, and Bacillus-based biocontrol agents can significantly reduce disease spread when disease pressure is moderate.

With growing emphasis on sustainability and reduced chemical inputs, this study highlights the promising role of biological control agents, especially B. velezensis strains, in future integrated pest management (IPM) strategies for mushroom production.

Reference

Clarke, J., Fitzpatrick, D.A., Kavanagh, K. et al. The control of mushroom pathogen Lecanicillium fungicola with fungicides and Bacillus-based biocontrol treatments during crop trial studies. BMC Microbiol 25, 767 (2025). https://doi.org/10.1186/s12866-025-04356-y