Control Methods for Four Types of Diseases in Edible Fungi

1. Brown rot

Also known as bubble disease, wet bubble disease, etc. It mainly affects button mushrooms, straw mushrooms, oyster mushrooms, etc. The disease is caused by a fungus called Mycogone perniciosa. The main characteristics are: the conidia and chlamydospores of Mycogone perniciosa only infect the fruiting bodies, not the mycelium. When the fruiting body is lightly infected, the stipe swells into a bubbly deformity, hence the name wet bubble disease. However, at different stages of fruiting body development, the symptoms also differ. When the fruiting body is infected before differentiation, an irregular mass of tissue resembling a hard-skinned puffball appears, covered with a layer of white cottony mycelium, and gradually turns dark brown, often exuding dark black droplets from the diseased tissue. When infection occurs after the cap and stipe have differentiated, the stipe turns brown, and infection on the gills produces two kinds of white mycelial growths.

Transmission route: Mycogone perniciosa is a common soil fungus, and the soil and waste around the mushroom house are its sources of infection. Therefore, the pathogen of Mycogone perniciosa is mainly carried to the mushroom beds and mushroom blocks through casing soil, air, operators, tools, insects, mice and other carriers.

Control measures: If the casing soil is contaminated by Mycogone perniciosa, it can be treated with pasteurization (60°C) for one hour, or the casing soil can be disinfected with 4% formaldehyde. Carbendazim solution or thiophanate solution at 1:500 can also be sprayed on the casing soil for sterilization. When the disease first appears, watering should be stopped immediately, the ventilation of the mushroom house increased, and 1%-2% formaldehyde solution or 1:500 carbendazim solution sprayed on the growing racks, walls and floor for sterilization. In severe cases, the original casing soil needs to be removed and replaced with new soil; the diseased mushrooms should be destroyed, and all tools disinfected in a 4% formaldehyde solution.

2. Withering disease

Also known as dead wilt disease, it is a physiological disease. It mainly affects button mushrooms, oyster mushrooms, Phoenix oyster mushrooms, Lingzhi mushrooms, nameko mushrooms, etc. The main characteristics are: after the mushroom buds form, fruiting bodies of various sizes can develop this disease. After onset, growth stops, they turn yellow, gradually shrink, soften and dry out, and finally die or rot.

Cause: The occurrence of this disease is the result of physiological obstruction. The main causes are that after primordium formation the substrate is too dry, causing the mushroom buds to wither; or that fruiting is too dense, so nutrients cannot be supplied adequately and some small mushrooms die; or that the temperature in the mushroom house is too high, the humidity too great, and ventilation poor, with insufficient oxygen, resulting in excessive carbon dioxide in the air; or that the small mushroom buds are accidentally bruised during harvesting, or that excessive fruiting produces phytotoxicity.

Control measures: When the fruiting bodies begin to wither, first determine the cause and take corresponding measures. Never spray chemicals inside the mushroom house after fruiting, otherwise phytotoxicity is likely to occur. In particular, for oyster mushrooms and Phoenix oyster mushrooms, dichlorvos must absolutely not be sprayed during the fruiting period.

3. Deformed mushroom disease

It is also a physiological disease. During the formation of fruiting bodies, if edible fungi encounter adverse environments and conditions that prevent the fruiting bodies from developing normally, various deformities will occur. The main characteristics are: small and thin caps, slender stipes, and early veil opening. This phenomenon occurs mostly after the first flush in oyster mushrooms and Phoenix oyster mushrooms, while in shiitake mushrooms it occurs in the first flush. Its main causes are high temperature, insufficient light, and lack of nutrients.

Long-stiped mushrooms mainly occur during the formation of fruiting bodies in the genus Pleurotus, where the fruiting bodies are coral-like or have extremely small caps while the base of the stipe is thick. The main causes are insufficient light, poor ventilation, excessive carbon dioxide, and too little oxygen. The tilting of fruiting bodies generally occurs toward the side with light, and the cause is the phototropism of the fruiting bodies during growth, mainly resulting from uneven light in the mushroom house. The phenomenon of mycelial shrinkage, and sometimes even death, that frequently occurs during different growth processes is mainly due to weak spawn that does not colonize the new substrate; or to unsuitable water content of the substrate, either too dry or too wet; or to excessively high temperature inside the substrate causing spawn burning, or poor ventilation inside the substrate, and possibly also unsuitable pH in the substrate.

There is only one control measure, which is that in the production process, every procedure and every process must be carried out scientifically and strictly according to requirements, so as to avoid various adverse consequences that lead to production failure.

4. Damping-off disease

Also known as wilt disease, it is a fungal disease. It is mainly caused by Fusarium and Fusarium solani f. sp. phaseoli. The main symptom is that after the fruiting body is infected, the pith of the stipe shrinks and turns brown, and the mushroom body becomes short and stunted, no longer growing. In the early stage of the disease, it is hard to notice any difference in appearance from healthy mushrooms; only the cap darkens, the mushroom body stops growing, and finally it becomes a mummified mushroom.

Transmission route: Because Fusarium can survive in soil for a long time, transmission through soil is the main route of infection; in addition, it can also be transmitted through air and some tools.

Control method: Sterilizing the casing soil is the main method of controlling this disease. Generally, carbendazim or thiophanate solution at 1:500 is sprayed for disinfection.