What are the main symptoms of mushroom Verticillium disease?

Verticillium disease is also called dry bubble disease, dry rot disease, black spot disease, etc. It belongs to the fungal phylum, Deuteromycotina, Hyphomycetes. Moniliales, Moniliaceae. In addition to harming mushrooms and oyster mushrooms, it also infects silver ear fungus.

[1]Symptoms: It generally does not infect the mycelium, only the fruiting bodies, but it can spread along the mushroom rhizomorphs. Dry rot spreads very quickly and has a strong infective ability against fruiting bodies. If damaged before primordium differentiation, it forms relatively dry grayish-white tissue masses that cannot differentiate to form stipes and caps, and later do not exude juice or have a foul odor. After young mushrooms are infected, the pathogen hyphae can invade the pith of the fruiting body, causing the base of the stipe to become abnormally swollen and brown, with the outer layer drying and cracking; while the cap develops slowly and becomes crooked, and the fruiting body appears as a deformed mushroom with a thick stipe and small cap and becomes rigid; if infected in the middle and late stages of the fruiting body, many irregular brown spots the size of a pinhead are also produced on the cap, and gradually expand to form depressions, with the depressed parts appearing grayish-white and filled with Verticillium conidia, the stipe thickens and turns brown, the outer tissue peels and cracks, and the diseased mushrooms are crooked and deformed, do not rot, have no odor, and finally dry, crack, and die. When the diseased mushroom is cut open and observed, its internal tissue is yellow-brown, dry, and loose. From infection to the appearance of brown spots in mushrooms, the disease course takes about 14 days.

This pathogen can also cause silver ear fungus stiff-shrink disease, causing the ear base to become stiff and stop growing after formation, appearing dark brown, with small ear pieces shrinking and unable to grow larger, and the overall shape appearing cauliflower-like; in some cases, part of the ear base is infected, causing one part to become stiff and shrunk while some ear pieces can still continue to open. Under moist conditions, a layer of white mold-like material quickly grows on the surface of the stiff ears, which consists of the pathogen's conidiophores and conidia.