Causes of Deformed Shiitake Mushrooms in Off-Season Cultivation and Their Prevention and Control Methods

The edible mushroom industry is an important part of agriculture. Vigorously developing the edible mushroom industry can not only promote a virtuous cycle of the ecosystem, but also increase farmers' income and improve agricultural efficiency, achieving an organic unity of economic, ecological and social benefits.

With the development of the edible mushroom industry, although shiitake production ranks only second, the economic benefits it delivers should rank first. How to improve shiitake yield and quality is of great significance to the many practitioners in the field.

In off-season cultivation of shiitake, deformed mushrooms often appear because production management is not in place, which directly affects the quality and economic value of the shiitake, greatly reducing the benefits. Apart from inferior spawn or viral infection, the causes of deformed mushrooms in off-season shiitake include selecting the wrong variety, improper management during the spawn-running period, failure of the bags to meet the standard after bag removal and color change, unsuitable soaking of the mushroom logs, and unreasonable temperature control and moisture retention.

Main manifestations of deformed mushrooms and their prevention and control methods.

1. Irregular caps: the caps appear narrow and elongated or triangular, crooked and misshapen rather than round. The main cause is that during the young bud stage the plastic bag was not cut open in time, so the caps pressed directly against the bag and were subjected to a certain amount of friction, or too many mushroom buds emerged and were not thinned in time, so that after cap differentiation they crowded together at the young bud stage, causing the young mushroom caps to be squeezed and unable to become round again. The prevention method is to cut the bag open in time and carry out bud thinning; generally only 1 to 2 young buds should be selected, and no more should be kept.

2. Small-cap mushrooms: the caps are both thin and small, cannot grow larger for a long time, and lack the distinctive aroma of shiitake when eaten fresh. The causes are: first, incomplete color change, with mushrooms fruiting from bags that are still mottled or white; second, insufficient nutrition in the bag substrate; third, excessively high temperature during the fruiting period. Prevention methods: always use bags with good color change for fruiting; if the bag substrate is nutritionally deficient, soak the bags to replenish it, or apply "foliar feeding" by spraying a special nutrient solution for edible mushrooms to increase cap thickness; when fruiting during high-temperature periods, effective cooling measures should be taken.

3. Wavy caps: the cap edges show a relatively regular wavy shape, and the caps are thin and brittle. The main cause of wavy caps is that the young mushrooms were stimulated by a large temperature difference during the development stage, while humidity in the environment also changed greatly, causing abnormal development of the cap tissue. The prevention method is to maintain relatively stable temperature and humidity after mushroom buds appear; especially in off-season cultivation in summer, the temperature of the mushroom shed is often the basic condition determining whether the fruiting bodies can develop normally.

4. Hollow stipes: the stipes are slender and hollow, and the caps are also very small. This is mainly caused by too low water content in the mushroom logs and too low air humidity. The preventive measure is to soak the fruiting bags after each harvest flush; generally soaking for one day and one night is enough to restore the bags to their original weight, while the air humidity in the mushroom shed should be kept above 85%.

5. Bent-stipe mushrooms: the stipes are twisted and not upright. The cause is that when light in the mushroom shed is relatively strong or the light angle changes too frequently, and the relative air humidity is low, this phenomenon is likely to occur. The prevention method is simply to maintain relatively stable air humidity and relatively stable diffused light.

6. Crack mushrooms: the stipes grow out from cracks in the substrate. The cause is that the water content of the bags is too low, causing the substrate to crack and form narrow, elongated openings, so that the fruiting bodies grow out from the cracks, or even fail to emerge completely, with the caps growing larger inside the cracks. The prevention method is to maintain the proper humidity and insist on soaking the bags after each harvest flush so that the substrate does not form cracks.

7. Bare-stipe mushrooms: only bare stipes are present, with no normal cap tissue. The causes are: first, the cap tissue was damaged at the young bud stage; second, ventilation in the shed was insufficient and the carbon dioxide concentration was too high. The prevention method is to cut the bags open in time, take care not to injure the buds intended to be kept during thinning, and maintain a well-ventilated environment so that the air in the shed stays fresh.