Cause Analysis and Control Measures for Physiological Diseases of Edible Fungi
During the cultivation of edible fungi, besides being infected by pathogens and failing to grow and develop normally, edible fungi are also affected by certain adverse environmental factors, which cause physiological disorders in growth and development and produce various abnormal phenomena, leading to reduced yield and declining quality. These are the so-called physiological diseases, such as excessive mycelial growth, deformed mushrooms, hard opening of caps, and dead mushrooms.
1. Excessive mycelial growth
This occurs during the cultivation of button mushrooms, shiitake mushrooms, oyster mushrooms and others. Under conditions of excessive humidity in the mushroom house (or mushroom bed) and poor ventilation, the mycelium grows too vigorously on the surface of the casing soil or the surface of the compost, forming a dense, water-impermeable mycelial mat, which delays fruiting or results in sparse fruiting and causes reduced yield. Besides being related to the above environmental conditions, excessive mycelial growth is also related to the spawn. During the isolation process of the stock culture, too much aerial mycelium is often picked, which frequently causes the mother culture and the cultivation spawn to clump, resulting in excessive mycelial growth.
During the cultivation of button mushrooms, once excessive mycelial growth appears, immediately strengthen the ventilation of the mushroom house, reduce the carbon dioxide concentration, reduce the moisture on the surface of the fine soil, and appropriately lower the temperature of the mushroom house to inhibit excessive mycelial growth and promote fruiting. If a mycelial mat has already appeared on the soil surface, break the mycelial film, then spray heavily with water and ventilate thoroughly; fruiting can still be expected.
2. Deformed mushrooms
During the cultivation of edible fungi such as button mushrooms, oyster mushrooms and shiitake mushrooms, irregularly shaped fruiting bodies often appear, or undifferentiated tissue masses form. For example, when cultivating oyster mushrooms, fruiting bodies resembling cauliflower often appear, formed by countless primordia clustered together, with a diameter ranging from several cm to more than 20 cm, with the stipe not differentiated or scarcely differentiated, and no cap. Deformed mushrooms that occur after primordium formation consist of abnormally differentiated stipes forming coral-like fruiting bodies, with no cap or a very small cap. In button mushrooms and shiitake mushrooms, deformed mushrooms such as those with enlarged stipes, small caps and thin flesh, or tall-stiped mushrooms without gills, often appear.
There are many reasons for the formation of deformed mushrooms in edible fungi, mainly excessive carbon dioxide concentration and insufficient oxygen supply; or casing soil particles that are too large, resulting in a low fruiting position; or insufficient light; or a relatively high temperature; or improper use of chemicals causing phytotoxicity, etc. Corresponding remedial measures should be taken according to the specific situation.
3. Rose comb disease
It mainly appears on button mushrooms. The edges of the caps of diseased mushrooms curl upward, forming gills on the upper surface of the caps; sometimes tumour-like growths in which gills and tubes cannot be distinguished form on the caps. Rose comb disease tends to occur more frequently in the first few flushes of mushrooms.
Rose comb disease is mainly caused by contamination with chemicals, such as mineral oil, creosote, phenolic compounds, or excessive use of fungicide pesticides, etc. It can be avoided by paying attention to these aspects in operation.
4. Thin skin and early opening of caps
During the peak fruiting season of button mushrooms, because fruiting is too dense and the temperature is relatively high (above 18 degrees), the phenomenon of thin skin and early opening of caps is very likely to occur, affecting the quality of the mushrooms. During cultivation, the mycelium should not be raised too high; the fruiting position should preferably be controlled between the cracks of the fine soil and between the coarse and fine soil particles; preventing overly dense fruiting and appropriately lowering the temperature of the mushroom house can reduce the phenomenon of thin skin and early opening of caps.
5. Hollow stipe with white core
During the peak production period of button mushrooms, if the temperature is relatively high (above 18 degrees), the relative humidity of the mushroom house is too low, and in addition the spraying of water on the soil surface is relatively little and the soil layer is rather dry, the stipes of button mushrooms are prone to develop a white core. During the cutting process, or during the soaking stage of processing, the white core part sometimes shrinks or falls off, forming button mushrooms with hollow stipes, which seriously affects the yield and quality of button mushrooms.
To prevent the occurrence of button mushrooms with hollow stipes and white cores, ventilate at night or in the morning and evening, appropriately lower the temperature of the mushroom house, and at the same time spray water into the air space of the mushroom house to increase the relative humidity of the air. Spraying should combine light and heavy watering, striving to keep both the coarse soil and the fine soil moist.
6. Hard opening of caps
When the temperature is below 18 degrees and the temperature difference reaches about 10 degrees, the young and tender fruiting bodies of button mushrooms often show early opening of caps (hard opening of caps). When there is a sudden drop in temperature and the air humidity in the mushroom house is relatively low, the phenomenon of hard opening of caps in button mushrooms is especially severe, seriously affecting the yield and quality of button mushrooms. Before the arrival of low temperatures, do a good job of keeping the mushroom house warm; reducing the temperature difference inside the house and at the same time increasing the relative humidity of the air in the mushroom house can prevent or reduce hard opening of caps in button mushrooms.
7. Water rust spots
Mostly seen on button mushrooms. When the mushroom house is poorly ventilated and the relative humidity of the air exceeds 95%, water often accumulates on the caps, or rust spots appear on the casing soil particles, both of which cause rust-coloured spots to appear on the surface of the button mushroom caps, affecting the appearance of the mushrooms. Avoiding the use of casing soil with rust colour, strengthening ventilation and moisture removal, and promptly evaporating the water droplets on the cap surface can prevent the occurrence of water rust spots on button mushrooms.
8. Dead mushrooms
Dead mushrooms occur during the cultivation of many edible fungi, including button mushrooms, shiitake mushrooms, straw mushrooms, oyster mushrooms and enoki mushrooms. Especially during the fruiting period of the first two flushes, small mushrooms often die in large numbers, seriously affecting the early yield. The causes of dead mushrooms are: first, fruiting is too dense and crowded, and the nutrient supply is insufficient; second, high temperature and high humidity, poor ventilation in the mushroom house or mushroom yard, and excessive accumulation of carbon dioxide, causing the small mushrooms to suffocate; third, too much water is sprayed during fruiting, and water is sprayed directly on the mushroom bodies, causing the mushroom bodies to become waterlogged and yellowed, and to rot and die; fourth, excessive use of chemicals produces phytotoxicity that harms the small mushrooms.