Investigating nematode challenges in Agaricus bisporus cultivation: a field analysis

Abstract: Bacterial-feeding nematodes pose a significant threat to mushroom cultivation,
particularly in white button mushrooms (Agaricus bisporus). These nematodes contribute to the spread of bacterial blotch on sporophores, cause deformities, and can lead to drastically reduced yields or complete crop failure. A study was conducted to investigate the population density of nematodes and their impact on A. bisporus. Samples were collected throughout the production cycle from two mushroom farms in Serbia, including compost (both spawned with A. bisporus strain F56 Italspawn and unspawned), casing material, and deformed mushrooms. Nematodes were found exclusively in peat samples, while the compost remained sterile. Before casing, nematode populations in peat were low, less than 10 nematodes per 100 mL of peat. 32 days after casing, an average of 630 nematodes per sample was detected. The genus Caenorhabditis was the most dominant, with populations ranging from 100 to 510 nematodes per sample. The second most abundant group belonged to the family Cephalobidae, with densities between 50 and 150 nematodes per sample. Other detected saprophytic nematodes included Acrobeloides, Heterocephalobus, Panagrolaimus, Plectus, and diplogasterids. By the 46th day after casing, the nematode population had further increased to an average of 880 per sample. At this stage, peat samples were suspected of nematode infestation as the mushrooms showed deformities, and Caenorhabditis sp. were isolated, with densities from 490 to 1500 per sample. Additionally, Caenorhabditis sp. was extracted from deformed mushrooms, averaging 10 nematodes per 100 g of mushrooms. The dynamics of these bacterial-feeding nematodes revealed their dominance in the cultivation process, suggesting favourable conditions in mushroom beds for their reproduction and survival. Despite measures like compost pasteurization, casing material disinfection, and farm sanitation, applied in this study, the persistence and rapid multiplication of Caenorhabditis species underline their significant threat to mushroom cultivation.