First report of Penicillium brevicompactum causing disease in Pleurotus ostreatus.

Oyster mushroom (Pleurotus ostreatus) is the second most produced mushroom globally, but increased production is linked to new diseases. This study reports the first occurrence of Penicillium brevicompactum on P. ostreatus mushrooms. Symptoms, identified in the primordia, include atrophy, malformation, drying, and sporulation, causing up to 100% losses. The pathogen was confirmed with 99% identity via ITS region analysis and phylogenetic comparison. The research highlights P. brevicompactum's infection of mushroom primordia, emphasizing the need for pathogen identification and preventive measures to mitigate production losses.