Comprehensive Control Methods and Technical Key Points for Mold Contamination in Nameko Mushroom Cultivation

Nameko mushroom, also known as slippery mushroom, has a delicious flavor and is rich in nutrients, enjoying a high reputation on the international market. In recent years, the nameko mushroom industry in our county has developed rapidly, but mold contamination occurs commonly, causing reduced yields in mild cases and total crop failure in severe cases. Therefore, whether mold contamination can be effectively prevented is the key to improving the quality and yield of nameko mushrooms.

1. Types of mold and their damage

In nameko mushroom cultivation, common contaminating molds include Trichoderma, Penicillium, Neurospora, and Aspergillus. These molds rapidly reproduce and spread under conditions of high temperature, high humidity, and poor ventilation, and in the later stage form green, blue-green, orange-red, yellow, or black mold-like substances on the surface of the substrate. At this point, the molds compete with the nameko mushroom mycelium for nutrients, and some secrete toxins, affecting the growth and development of the nameko mushroom, among which Trichoderma is the most harmful.

2. Contamination pathways

2.1 Substrate contamination. Improper substrate formula, excessive moisture in the medium, and incomplete sterilization.

2.2 Inoculation contamination. Unsuitable spawn type, impure spawn, poor vitality, unsanitary inoculation environment, improper inoculation method, and common mold contamination around the inoculation blocks. When the inoculation amount is less than 5%-10%, the growth advantage of the nameko mushroom is not obvious, and molds will also infect and reproduce.

2.3 Bag hole contamination. Plastic bags become brittle and cracked, have micropores or mechanical damage, and contaminating bacteria enter through the gaps, quickly forming obvious contamination centers.

2.4 Cultivation contamination. This situation often manifests as poor air permeability of the bagged spawn, as well as high-temperature and high-humidity environments suitable for mold reproduction.

3. Comprehensive control measures

To ensure the normal growth and development of nameko mushrooms and achieve the goal of high quality and high yield, the policy of giving priority to prevention and comprehensive control should be adopted.

3.1 Correctly select and treat the substrate. Before mixing the substrate, the raw materials should be exposed to the blazing sun for 3-4 days to reduce contaminating bacteria in the material. When mixing the substrate, use 0.2% of 40% carbendazim for sterilization, or use 0.1% thiophanate-methyl or 0.1% prochloraz for mixing.

3.2 Strictly control the inoculation step. High-quality and suitable spawn is the foundation of successful cultivation. When selecting spawn, it is advisable to choose spawn with a spawn age of 25-35 days, dense and white mycelium, no accumulated water or detachment from the wall, no formation of fruiting body primordia, and no contamination. With suitable raw materials and high-quality spawn, it is also necessary to maintain the cleanliness and hygiene of the inoculation site, tools, and inoculation personnel to prevent transmission and infection.

3.3 Protect the cultivation bags well. The plastic bags used for cultivation should be of good quality and uniform in thickness. Avoid using sharp and hard objects, ensure the ground in contact with the bags during filling is smooth, handle them gently during movement, and make sure the tools used for carrying are smooth or have padding. Both tools and hands need to be disinfected during carrying.

3.4 Proper cultivation management. Place the inoculated spawn bags at 15-25°C for mycelial growth. At a temperature of about 20-25°C, an air relative humidity of 85-95%, the nameko mushroom mycelium grows rapidly, and contaminating bacteria are less likely to occur. If the temperature reaches 28-32°C, the air relative humidity is above 95%, and the pH is 3.5-6.0, it will create a growth advantage for contaminating bacteria such as Trichoderma and Penicillium. If a large amount of accumulated water is found at the bottom of the bag, puncture holes in time to drain the water and change the position of the spawn bags; otherwise, molds will rapidly contaminate them. In addition, during the mycelial cultivation period, ventilation and air exchange should be carried out frequently to maintain normal temperature and humidity and ensure normal mycelial growth.

3.5 Scientific use of chemicals. Frequently inspect the spawn bags, and promptly handle mold contamination to avoid spread. When mold occurs in spots, inject 1% prochloraz into the affected area. If the contamination is relatively severe and appears in local patches, first dig out the mold and spray 5% lime water on the affected area. If the contamination is severe, promptly clean it up and dig a pit for deep burial.