Characterization and chemical control of soft rot disease caused by Pantoea sp. strain PPE7 in Pleurotus eryngii mushroom crops

The bacterial pathogen Pantoea sp. strain PPE7 causes severe soft rot disease in the king oyster mushroom, Pleurotus eryngii. Typical symptoms of the disease include a dark-brown water drop at early stages of infection, ultimately leading to soft rot accompanied with an offensive odour. In this study, we showed that inoculation of Flammulina velutipes and Agaricus bisporus mushrooms with Pantoea sp. strain PPE7 also resulted in severe disease, including water-soaked lesions and soft rot symptoms. Treatment with chlorine solution (175 to 700 ppm active chlorine) significantly reduced the incidence of soft rot symptoms in Pleurotus eryngii. However, exposure to concentrations greater than 350 ppm caused harmful effects such as bleaching on the cap of the fruit body. Calcium hypochlorite solutions with 175 ppm active chlorine were effective for reducing soft rot disease of Pleurotus eryngii without affecting the mushroom yield.