Identification and Control Methods of Mucor Disease in Lingzhi (Reishi Mushroom)
Mucor mucedo (L.) Brefeld belongs to the subphylum Zygomycotina, order Mucorales, genus Mucor. It can infect edible fungi such as lingzhi (reishi mushroom), silver ear fungus, and oyster mushroom, and is a common contaminating fungus in mushroom cultures. It grows rapidly and occurs commonly. In severe cases, it can cause the entire culture to be discarded.
Symptoms: Mucor can secrete organic acids and toxins that inhibit the growth of lingzhi mycelium. After the substrate is affected, the mycelium appears grayish-white and relatively thick, and grows rapidly. In the later stage, many yellow-white round small granules form at the tips of the aerial mycelium, which gradually turn black. Mucor competes with lingzhi mycelium for nutrients and water, inhibiting mycelial growth.
Pathogen: Mucor belongs to the subphylum Zygomycotina. When grown on potato sucrose agar medium, the aerial mycelium is grayish-white to grayish-black. When growing in culture bottles or bags, the mycelium is initially white, then turns grayish-white or pale yellow, sparse and thick. Sporangiophores arise from the aerial mycelium; the stalks are long and thick, unbranched. The sporangia are spherical and contain many sporangiospores. The sporangiospores are oval, colorless or pale yellowish-brown, and single-celled. Short stalks may grow near the base of the sporangiophores, forming small sporangia at the tips; the small sporangia contain 1 or several spores. The hyphae are non-septate, and aged hyphae may form chlamydospores in the middle. During sexual reproduction, spherical zygospores can form.
Disease characteristics: Mucor often lives on organic matter. Mature spores disperse in the air, and when temperature and humidity are suitable, they germinate into hyphae on organic matter, especially under high temperature and high humidity conditions, where they grow rapidly. During the culture growth process, contamination can be caused by incomplete disinfection and sterilization of the substrate and inoculation tools, failure of workers to strictly follow aseptic operation requirements, or damp cotton plugs on culture bottles or bags. If the cultivation room remains poorly ventilated for a long time, the incidence rate is high.
Control Methods
(1) Choose a suitable cultivation site, away from substances containing organic matter such as livestock and poultry manure.
(2) Strengthen cultivation management, provide timely ventilation, maintain appropriate temperature and humidity in the cultivation room, keep the environment clean and hygienic, and destroy the living environment of the pathogen.
(3) Use fresh, dry raw materials free from mold as the substrate; when mixing the substrate, control the proportion of wheat bran and rice bran to within 10%.
(4) When mixing the substrate, use 25% or 50% carbendazim at 0.2% of the dry material weight, or thiophanate-methyl at 0.2% of the dry material weight.
Commonly used fungicides: carbendazim and thiophanate-methyl.