Common pest and disease control methods and key technical points for shiitake mushrooms

During the production of shiitake mushrooms, they are often harmed by pests and diseases. If control is poor, shiitake cultivation can fall into a vicious cycle, causing reduced yields in mild cases or complete cultivation failure in severe cases, so great attention must be paid to this.

1. Trichoderma

Trichoderma, also known as green mold, is widely distributed in various plant residues, soil and air. Trichoderma spreads through spores, often using air currents, water droplets, insects, raw materials, tools, and the hands and clothing of operators as media to invade the culture medium, and once conditions are suitable, it germinates and reproduces to cause harm. When the production environment is unclean, the culture material is not thoroughly sterilized, inoculation operations are not strict, and conditions are hot and humid, this creates a good opportunity for Trichoderma infection, especially in mushroom farms and old mushroom houses that have been used for many years, which are often places where Trichoderma causes rampant damage.

Among all the contaminating fungi that harm shiitake growth, Trichoderma is the greatest threat. Trichoderma has strong adaptability and a fast reproduction speed. It can itself secrete toxins that inhibit the growth of shiitake mycelium. Trichoderma can grow on shiitake mycelium with weakened growth vigor, causing the shiitake tissue cells to dissolve and die.

Trichoderma can grow within the range of 4-42°C. Spore germination favors a highly humid environment. When it infects shiitake culture material, it is white and cottony at first, then turns green later. If mushroom spawn is harmed by Trichoderma, it must be discarded. Even spawn with mild infection should be discarded without regret.

To date, there is no ideal curative drug for Trichoderma. Commonly used fungicides only inhibit Trichoderma rather than kill it. Increasing the dosage only kills both Trichoderma and shiitake mycelium at the same time. Therefore, creating an ecological environment suitable for shiitake mycelium growth but unfavorable for Trichoderma reproduction is the fundamental measure to control the harm.

Once Trichoderma damage occurs, ventilation and humidity reduction should be carried out immediately to inhibit the expansion of Trichoderma. After the culture material in the mycelium-growing stage becomes infected, the method of injecting medicinal solution can be used to inhibit Trichoderma expansion. Commonly used solutions include 5% carbolic acid, 2% formaldehyde, 1:200 dilution of 50% carbendazim, 75% thiophanate-methyl, and limewater with a pH value of 10. In addition, scattering white lime powder on the contaminated area also gives good control results.

2. Neurospora

Neurospora appears fluffy at the early growth stage, white or gray, and pink or yellow at the later growth stage. When a large number of conidia accumulate into clumps, it looks similar to the fruiting body of Hericium erinaceus. Neurospora mainly spreads and causes harm through conidia, and is the most important contaminating fungus occurring in high-temperature seasons. Neurospora hyphae are tenacious and strong, with the characteristic of rapid reproduction. Once it breaks out on a large scale, it is a disaster, and the consequence is that spawn, culture bags or culture blocks are discarded in batches.

To control Neurospora, first try as much as possible to avoid production in high-temperature seasons. During the shiitake mycelium-growing stage, the temperature is best controlled below 20°C, so that Neurospora grows slowly and contamination can be reduced. Dampness in the shiitake mycelium-growing site helps the occurrence of Neurospora, so controlling the humidity of the mycelium-growing site can effectively prevent the occurrence of Neurospora. For chemical control of Neurospora, refer to the control of Trichoderma. During bag production, if Neurospora is found, drip diesel oil onto the conidial mass to prevent the spread of Neurospora. If damage occurs in the later stage of mycelium growth in bags, generally do not discard them lightly. The affected bags can be buried in soil with poor air permeability at a depth of 30-40 cm. After 10-20 days of oxygen-deficient treatment, the disease can be effectively reduced, and the bags can still produce mushrooms.

3. Mucor

Mucor is also called black mold or long-haired mold. The hyphae are white at first, then gray-white to black, indicating that the sporangia have matured in large numbers. This fungus exists everywhere in soil, manure, grass and air. Its incidence is high under conditions of relatively high temperature, high humidity and poor ventilation. Its growth speed is clearly higher than that of shiitake mycelium. Mucor mycelium can extend about 3 cm per day.

When Mucor infects during the cultivation period of shiitake mycelium, it spreads quickly and can cover the substrate within a few days, while the harmed shiitake mycelium grows slowly and struggles along. Although it can eventually still extend to all parts of the substrate, the shiitake mycelium no longer has its normal dense white color, but is gray-yellow.

The main reasons for its occurrence are the use of moldy raw materials in the substrate, a high content of Mucor spores in the inoculation environment, and mycelium cultivation in a stuffy and humid environment, among others. The control methods are the same as for Trichoderma.

4. Mites

Mites include red spiders and mushroom lice. Their occurrence environment is mainly hidden in barnyard manure, feed and culture material. Chicken coops, livestock sheds, grain warehouses, or places with poor environmental conditions and rich humus often contain large numbers of mites. Mites are very tiny, and early occurrences are often ignored. Once they break out, they can easily cause major disaster. Mites can cause harm at all stages of shiitake production, feeding on shiitake mycelium and fruiting bodies.

After the culture medium is affected by mites, the spawn blocks at the inoculation site do not germinate, or after germination the mycelium appears sparse and dim and gradually shrinks. In severe cases, the mycelium in the culture material will be completely eaten up, causing cultivation failure.

Doing a good job of environmental sanitation in the fungus-cultivation site can effectively eliminate the occurrence of mite damage. For fungus-cultivation rooms where mite damage has occurred, fumigate with drugs such as dichlorvos to kill mites before reuse. During mycelium cultivation, spraying 1000-fold dilution of dicofol or 500-fold dilution of propargite gives better results. Drugs should not be used during the fruiting body cultivation period; otherwise, the mushrooms are prone to phytotoxicity, and eating them harms human health.