Control Methods for Malformed Mushrooms in Off-Season Cultivation of Shiitake

In off-season cultivation of shiitake (Lentinula edodes), malformed mushrooms often occur because production conditions are not properly regulated, affecting the commercial quality and value of the mushrooms and greatly reducing production efficiency. The main manifestations of malformed mushrooms and their control measures are:

1. Small and thin caps. This manifests as caps that are both thin and small; even after a long growth period they cannot grow larger, and when eaten fresh they lack the distinctive aroma of shiitake. Control method: for bags that have not undergone color change, conditions must be regulated to induce color change; if the substrate nutrients are insufficient, they can be appropriately supplemented when soaking the bags, or the method of "foliar fertilization" can be adopted, such as spraying edible mushroom three-dimensional nutrient essence, which can effectively thicken the caps; in summer when temperatures are relatively high, effective cooling measures should be taken, and using a "water-cooled air conditioner" gives better results.

2. Lampshade-shaped caps. The cap takes on a pointed lampshade shape and is noticeably thin, seriously reducing commercial quality. The main cause is the same as above. Therefore, control can be carried out by referring to the above.

3. Wavy caps. The cap edge takes on a relatively regular wavy shape and is also noticeably thin and brittle. The occurrence of the wavy shape is mainly related to young mushrooms being exposed to a relatively large temperature difference during the development stage, while humidity changes in the environment are also very large; especially when large amounts of water are sprayed directly onto the caps and a relatively strong airflow then blows past, the cap tissue develops abnormally. Control method: after mushroom buds appear, relatively stable temperature and humidity should be maintained; especially in off-season summer cultivation, the temperature of the mushroom shed is often the basic condition determining whether the fruiting bodies can develop normally.

4. Irregular caps. This specifically manifests as caps that are crooked and twisted, or elongated, or triangular, and so on; in short, not being round and regular is their main feature. The main cause is that during the young bud stage the film was not cut open in time, so the caps pressed directly against the film and received a certain amount of friction; or too many mushroom buds developed and were not thinned in time, so by the young bud stage, after cap differentiation, they were crowded together. As long as the cap is squeezed when young, it will never become round and regular again. Control: cut the film in time and carry out bud thinning.

5. Hollow stipes. The stipes are slender and hollow, causing the caps to also be very small; this is mainly caused by too low a moisture content in the substrate and too low a spatial humidity. Control measures: after each harvest flush, the bags should be soaked; generally soaking for 24 hours can restore them to their original weight, and the air humidity in the mushroom shed should be kept above 85%.

6. Stipes growing out from cracks. When the moisture content of the mushroom bag is too low, the substrate cracks; after long narrow cracks form, some fruiting bodies grow out from within the cracks, and some do not even fully emerge, with the caps growing larger inside the cracks, ultimately failing to achieve their commercial value. The preventive method is to persist with soaking the bags so that cracks do not form.

7. Twisted stipes. This phenomenon is likely to occur when the air humidity in the mushroom shed is relatively low, the light is relatively strong, or the light angle changes too frequently. The preventive method is to maintain relatively stable air humidity and relatively stable light; generally, 1000 lux of scattered light is sufficient.

8. Candle mushrooms. The characteristic of candle mushrooms is a bare stipe with no normal cap tissue, shaped like a candle. Causes: first, the cap tissue was damaged during the bud stage; second, the carbon dioxide concentration in the shed is too high. Preventive measures: cut the film in time; when thinning buds, be careful not to damage the buds intended to be retained; maintain good ventilation and keep the air conditions in the shed relatively fresh.