Control Methods for Green Mold Disease in Lingzhi (Reishi Mushroom)
Green mold (Trichoderma viride Pers. ex Fr.) belongs to the class Hyphomycetes, order Moniliales, family Moniliaceae, genus Trichoderma, under the subdivision Deuteromycotina.
1. Morphological characteristics: The hyphae are slender, colorless, septate, and much branched. Conidiophores arise from lateral branches of the hyphae, opposite or alternate, generally with 2-3 branchings; the sterigmata bearing conidia are flask-shaped or cone-shaped. Conidia are mostly spherical, with the spore wall bearing small warty protuberances, green or blue-green. On PDA medium, the colony is initially white and cottony, later becoming dark green.
2. Disease development pattern
(1) Transmission routes: Conidia are spread by airflow, water, insects, and other means. Old mushroom houses, contaminated tools, and raw materials are the main sources of primary infection. The conidia produced after infection can cause repeated secondary infections many times over.
(2) Conditions for occurrence: Widely distributed in soil, air, and various organic matter in nature; infection occurs easily whenever the substrate is not thoroughly sterilized or is poorly composted and fermented. At temperatures of 15-30°C, green mold spores have the highest germination capacity; the hyphae can grow within the range of 4-42°C, with fastest growth at 25-30°C; a high-temperature environment favors spore germination and hyphal growth; it prefers a slightly acidic environment, but does not die even when the pH rises above 7.
3. Symptoms of damage: During both spawn expansion and cultivation, infection and damage by Trichoderma can occur. Green mold has strong adaptability to the environment, and the cellulase, cellobiase, and other enzymes it contains are highly active, making it extremely prone to developing on substrates rich in lignin and cellulose. Once it infects, it grows and spreads rapidly, turning the entire substrate layer green, and it secretes toxins that destroy the host's hyphae and cytoplasm, causing the host to die quickly. It can be called a devastating, catastrophic disease and contaminant.
4. Control methods
(1) Focus on prevention, do a good job of cleaning and sanitation at the production site, and ensure ingredients are fresh and sufficiently dry, the formula is correct, and sterilization is thorough.
(2) If contamination is found during spawn production, it should be discarded and redone; when cultivation bags are contaminated, in mild cases the affected area can be dug out and lime powder or fungicide applied locally, while in severe cases they should be burned; when log cultivation is locally contaminated, use a sharp knife to shave off the bark and wood of the affected part and apply fungicide, and if the contamination is severe and widely distributed, they should be gathered and burned.
(3) When mixing the substrate, add 0.1% of 70% thiophanate-methyl, which after autoclaving can achieve a relatively good control effect.