Isolation and identification of Pseudomonas tolaasii causing brown rot on Morchella sextelata in Guizhou Province, China

Morchella sextelata is an economically important edible mushroom. From February to April 2022, brown rot symptoms were observed on the stipe of M. sextelata in three mushroom farms in Guizhou Province, China. The disease incidence was approximately 10–15%, which led to significant yield losses. We isolated and purified three pathogenic bacterial isolates and conducted morphological and biochemical tests, molecular identification, and pathogenicity tests. Based on the results, the pathogen responsible for stipe brown rot was identified as Pseudomonas tolaasii. To the best of our knowledge, this is the first report of P. tolaasii causing stipe brown rot disease in M. sextelata in China. Our findings provide insights into the identification of stipe brown rot in M. sextelata cultivation.