How to prevent contamination in mushroom spawn production? Mastering cultivation techniques is key

In the process of mushroom production, spawn production is a key step. During the making of spawn, improper operation, incomplete disinfection and other reasons can lead to the invasion of contaminant fungi, contaminating the spawn, reducing the marketable rate of mushrooms and lowering profits. Below is an introduction to the common contaminant fungi in mushroom production and their control measures:

1. Penicillium is one of the most common contaminant fungi. After contamination, it appears on the culture medium as small, separate green powdery mildew spots. This fungus is extremely widely distributed, spreading by means of conidia in the air that attach to moist materials that have not been thoroughly disinfected. Control measures: the culture material must be strictly disinfected; during inoculation, aseptic technique must be strictly observed; strengthen ventilation, lower temperature and reduce humidity; for local contamination, wash with 5-10% limewater.

2. Trichoderma is mainly Trichoderma viride or Trichoderma koningii. It spreads by means of spores produced in organic matter such as decaying wood, seeds, plant residues, compost and soil, as well as spores floating in the air. This fungus prefers acidic conditions, and occurs easily when the temperature reaches 25-30°C and the relative humidity of the air is 80-90%; it can spread from small spots to the entire surface of the material within 3-5 days. Control measures: (1) Strictly disinfect the culture material to thoroughly eliminate the mycelium and spores in it; carry out aseptic operation well and strengthen ventilation and cooling. (2) When disinfecting, do not use too much formaldehyde, to prevent creating an acidic environment. (3) When Trichoderma appears on the culture medium, promptly apply 755 alcohol, 15% bleaching powder solution, or 50% carbendazim 200-fold dilution to the affected area, spray 1-5% limewater or scatter white lime powder, then dig it out, and afterward smear with limewater. When treating, it is best to move the spawn bags (bottles) outdoors to prevent the spores from scattering. After Trichoderma appears, it is strictly forbidden to open the bottle caps or lift the film at will, to avoid spreading. When using plastic bags for spawn production, they should not be moved too much during the cultivation period. (4) Promptly remove the spawn blocks that have not germinated. (5) The cotton plugs of spawn bottles and spawn bags must not become damp; keep the cultivation room dry and clean. (6) The mother spawn must be pure. (7) When mixing the material, add 2 g of 25% (or 5%) carbendazim or 1 g of 75% thiophanate-methyl per kilogram of dry material.

3. Mucor, Rhizopus and Aspergillus. Mucor, also known as long-hair fungus, mainly occurs on the culture medium and spawn during the early stage of indoor cultivation of mushrooms (fungi). The mycelium is initially white or grayish-white, later turning pale yellow. The mycelium is sparse and stout, each strand clearly visible. The higher the water content of the culture material, the more severe the occurrence. It has a strong ability to decompose starch and grows very fast. Control measures: (1) Thoroughly disinfect and sterilize, and do a good job of aseptic operation. (2) When mixing the material, add 2 g of 25% (or 5%) carbendazim, or 1 g of 75% thiophanate-methyl, per kilogram of dry material.

4. Neurospora, also called Neurospora sitophila, can cause harm during the production process of spawn at all levels. It occurs especially easily when the temperature is high and the humidity is high. This fungus is very widely distributed in nature, and readily occurs on various organic materials such as corncobs, corn stalks, cottonseed hulls and waste cotton. Its conidia float everywhere. Control measures: (1) Do a good job of environmental sanitation; waste culture material should be buried deep. (2) Thoroughly sterilize the culture material; cotton plugs must not become damp, and should be replaced promptly once damp. Spawn bottles (bags) must be free of damage. (3) The inoculation room must be thoroughly disinfected, and aseptic operating procedures strictly observed. (4) Scatter lime on the floor, and if necessary also on the cotton plugs at the bottle mouths, to keep them dry. Once discovered, promptly remove and burn them, and spray with 75% wettable thiophanate 500-fold dilution, or fumigate with 10 milliliters of formaldehyde per cubic meter of space. (Source: Gansu Farmers' Daily)