What are the control methods for mushroom mycelium shrinkage?

In mushroom cultivation, it is common to encounter mycelium that does not colonize the substrate after germination, turns yellow and shrinks, seriously affecting the development of mushroom production. The causes and control methods are described below:

1. High-temperature burning of the mycelium. The sowing period has high temperatures, the compost is too thick, and the substrate temperature does not steadily drop after fermentation, so the temperature inside the compost rises above 30°C.

Control methods. The sowing period for mushrooms should avoid the high-temperature period; at sowing time the substrate temperature should be stable below 25°C. If mycelium is found to have shrunk due to high temperature after sowing, the pile should be turned again for ventilation, then the moisture of the compost should be readjusted and sowing carried out again.

2. Ammonia gas in the substrate. Too much nitrogen fertilizer was added when building the pile, or the nitrogen fertilizer was added too late (only added during the later turnings), so ammonia gas is present in the compost after the spawn is sown.

Control methods. When adding chemical fertilizers such as urea to the compost, first, they should be added when building the pile, and second, the amount should be appropriate. If ammonia gas is found in the substrate, open the doors and windows promptly, spray a 2% formaldehyde solution and turn the substrate; after the ammonia smell is gone, sow again.

3. The compost is too dry. At sowing time the compost is rather dry; if the weather is also dry, the mycelium grows slowly through the substrate after germination, becoming thin and weak and then shrinking.

Control methods. A layer of wet rice straw (soaked in 0.5% lime water) can be spread over the surface of the substrate, which enables the mycelium to germinate and colonize the substrate again. If sowing is met with dry weather, close the doors and windows for 3 days after sowing. Using layer sowing plus a surface-covering sowing method is better.

4. Too much water in the substrate. The compost has too high a water content; after casing soil is applied, high temperatures occur again, or heavy watering is done during high temperatures without timely ventilation, so the mycelium shrinks because of insufficient oxygen supply and reduced vitality.

Control methods. Pay attention to controlling moisture when piling the compost. If the water content of the substrate is found to be too high during turning, spread it out to dry slightly and then pile it again. The water content of well-fermented compost is preferably 60-65%. For mycelium shrinkage caused by heavy watering in the later stage, the mycelium can resume growth after ventilation. The total thickness of the casing soil layer on the bed surface should not be less than 4-4.5 cm.

5. Poor-quality spawn. The spawn was heated during transport, reducing mycelial vitality; the spawn was not used in time and aged, so its growth vigor weakened; and if it then encounters an unfavorable environment after sowing, all of these can cause the mycelium to shrink.

Control methods. Choose a suitable compost for cultivating spawn; the spawn should have thick, strong mycelium and strong germination ability; avoid hot days when purchasing spawn; do not use aged spawn for sowing.

6. Insect pests. The main pests are mites, which are not easily seen with the naked eye in the early stage and mainly damage the mycelium, causing it to break and shrink. Pests can be brought in with both the compost and the casing soil, and can cause serious damage.

Control methods. The occurrence of mites is related to the compost, casing soil, spawn and so on, so integrated control should be carried out. Do a good job of the secondary fermentation of the compost; the casing soil should be treated for insect control; the spawn should be fumigated with dichlorvos 1 day before sowing, etc. In addition, scattering Baogu powder into the substrate before sowing can provide effective control. If mites are found during cultivation, use pesticides for control as early as possible.