Bacterial blotch of mushrooms

Pseudomonas agarici is a pathogenic bacterium responsible for causing bacterial blotch, a significant disease affecting cultivated mushrooms such as Agaricus bisporus. It is a major concern in commercial mushroom production due to its ability to rapidly spoil the quality of the harvested produce.

The characteristic symptoms of the infection appear as yellow, golden, or brown lesions on the surface of the mushroom caps. These spots are initially small but tend to enlarge and become darker over time. In severe cases, the lesions become sunken and exhibit a slimy texture, leading to total degradation of the mushroom tissue.

The development of the disease is highly dependent on environmental conditions, specifically moisture levels. High relative humidity, combined with the presence of water droplets on the mushroom caps for extended periods, creates the perfect conditions for the proliferation of Pseudomonas agarici and subsequent infection.

The economic impact of this disease is significant, as infected mushrooms are immediately rejected by quality control standards. Even mild infections can render the crop unsellable, forcing growers to discard large portions of their yield, which impacts the overall profitability of the mushroom operation.

Effective prevention and control measures focus on managing the growing environment to suppress bacterial growth. Key strategies include maintaining proper ventilation to ensure that moisture evaporates quickly from mushroom surfaces after watering, regular sanitation of all equipment, and ensuring that the casing soil is free from pathogens.