Identification and control methods for several common diseases of edible fungi
I. Causes of deformed mushrooms and measures to avoid them
Deformed mushrooms lower product grade and may even lose their commercial value, affecting the economic benefits of cultivation; this problem is widespread. Common deformed mushrooms include: caps tightly clasped and not opening, appearing "fist-shaped"; stipes long, thick and fleshy with small caps, appearing "vase-shaped"; caps sunken with cracked, outward-curling edges, appearing "broken-bowl-shaped"; caps narrow and long, appearing "ox-tongue-shaped"; caps with spots on the surface, appearing "pockmarked"; caps with swollen tumor-like protrusions in the center, appearing "belly-swollen"; two caps spreading side by side with stipes tightly joined, appearing "butterfly-shaped"; caps curved and uneven, appearing "wavy-edged"; caps round and wrapped with shrunken gills, appearing "bald-headed"; caps with longitudinal cracks and fissures on the surface, appearing "flower-mushroom-shaped"; several mushrooms growing together, appearing "lotus-shaped"; in addition, there are also shriveled mushroom forms, yellowish discolored mushroom forms, and so on. The occurrence of deformed mushrooms is ultimately due to the fact that the cultivation environment conditions are incompatible with the physiological and biochemical requirements of white king oyster mushroom (Pleurotus nebrodensis). The key lies in poor coordination of temperature, humidity, light and air during the fruiting period, and operational errors in management techniques, and so on. A detailed analysis follows, along with corresponding measures to avoid the occurrence of deformed mushrooms.
1. Unreasonable house and shed structure
Many of the existing white king oyster mushroom cultivation sites (indoor mushroom houses and field mushroom sheds) are crudely built with unreasonable structures. Some mushroom houses have doors and windows on only one side, and some have ventilation openings in the upper half of the wall, resulting in no air circulation in the room; some plastic greenhouses have ventilation openings on both sides, but the openings all face the two ends of the mushroom walls; and some, although they have ventilation openings, never open them in order to keep warm. Because the air in the shed does not circulate, severe oxygen deficiency occurs, causing the aerobic white king oyster mushroom to become deformed. An ideal mushroom shed should face south from a north-facing orientation or face east from a west-facing orientation. From the standpoint of heat preservation and ventilation, the cultivation house or shed should not be too large; generally, for a rectangular shed, a capacity of 3000 bags (15×8×2.2 m) or 5000 bags (25×8×2.2 m) per shed is suitable. Ventilation openings should be set low on both long sides, built with bricks to a 24×24 cm opening, with one opening every 1 m; the openings on the two lateral sides should be at the same height, which helps air convection. The doors and films at both ends of the mushroom shed should be able to open and close, which helps longitudinal air convection; the shed roof should use anti-drip film plus straw curtains or shade netting.
2. Improper stacking of mushroom walls
Its manifestations: mushroom bags are stacked too high when entering the shed, 10 bags to a stack, exceeding 1 m; some mushroom walls are filled with clay soil between them, which is impermeable to air; some are watered insufficiently after soil filling and are on the dry side; some mushroom walls are stacked too densely with no soil filled in between; some, when building the walls, do not cut the film at the bag ends properly, cutting only 1/3 of the film on the part entering the wall, which is too little, while instead cutting the film on the exposed outer end, leaving the mycelium exposed to the air without moisture retention. These things inevitably inhibit the growth and development of the fruiting bodies. For example, in the north, when mushroom bags are stacked into walls and the soil between the bags has insufficient water, when winter heating and primordium induction begin, the moisture is low and on the dry side, and the water content inside the mushroom bags is instead absorbed by the filling soil, dehydrating the mycelium, inevitably producing deformed mushrooms with unopened or shriveled caps; and clay soil becomes compacted and has poor air permeability, so it cannot regulate the mycelium and instead hinders normal physiological reproduction.
In mushroom-growing areas north of the Yangtze River, stacking mushroom bags into walls is the carrier for white king oyster mushroom fruiting, and it includes both the mushroom bags and the filling soil. The purpose of filling soil is to utilize the organic matter in the soil while also regulating temperature and humidity. At low temperatures the soil can preserve heat, and when the temperature is high it dissipates heat; this is a soil-covering cultivation mechanism and is also a current model for field mushroom shed cultivation of white king oyster mushroom. To achieve timely fruiting and good mushrooms, according to large-scale production practice experience in Guangshui City in northern Hubei, the "five requirements" must be met: 1) Timing must be accurate. After the mushroom bags reach physiological maturity, this should generally be completed in early to mid-December so as to shift to primordium induction; 2) Wall stacking must be stable. Mushroom bags should be stacked 6-7 layers in a slanted form, wide at the bottom and narrow at the top, with a bottom width of 120 cm, top width of 80 cm, and wall length of 280 cm as suitable; the working aisles between mushroom walls should be 60-80 cm apart; 3) Film cutting must be appropriate. The purpose of cutting the film on the end of the mushroom bag facing inward is to let the mycelium connect with the filling soil, and cutting off 2/3 is suitable; when stacking the walls, 2 bags are placed side by side, with 4-5 cm between bags; the exposed outer end should be left with 1.5-2 cm and the film must not be cut, serving to protect and enclose the fruiting body; 4) Soil filling must be good. For building the wall, clay is suitable, but the soil filled between mushroom bags should be clay plus sandy loam, mixed with 1% lime and 0.5% compound fertilizer to make a nutrient soil; it is used in two parts, one part mixed with water into a mud for building the bags, and one part dry-mixed as filler for the gaps and trenches between bags, followed by watering; 5) Air holes must be made. After filling soil 3 cm on top of the mushroom wall, use mud to form a water storage area about 10 cm deep, and every 40-50 cm make a hole 3 cm wide extending down to 2-3 bags from the bottom of the mushroom wall, serving both as ventilation holes and for irrigation.
3. Congenital nutritional deficiencies
There are 4 manifestations: 1) The raw and auxiliary materials in the formula, cottonseed hulls and wheat bran, are aged, damp and moldy, with degraded nutrients; and the amount of wheat bran, a nitrogen-containing substance, in the formula is too small, so there is no adverse reaction in the early stage of mycelial growth, but by the fruiting stage it cannot meet the requirements; 2) The culture medium turns sour and spoils; 3) Water in the mushroom bags evaporates and the mycelium dehydrates. These belong to congenital malnutrition, so the mushrooms produced have thin caps, wavy edges, or unopened caps and yellowish rather than white discoloration.
The culture material is the medium for the growth and development of white king oyster mushroom fruiting bodies, and the quality of the substrate is closely related to how many and how good the mushrooms are. To produce more high-quality mushrooms, the "four musts" are required: 1) Raw materials must be fresh and free of mold, and sun-dried for sterilization before use; 2) The formula must be reasonable. Here are 2 formulas: cottonseed hulls 87%, wheat bran 8%, cornmeal 2%, lime powder 3%; a formula based mainly on sawdust: broadleaf tree sawdust 80%, wheat bran 15%, cornmeal 3%, lime powder 2%. Water content about 60%, pH 7-8.5. 3) Additives must be controlled. The additives commonly used in formulas are gypsum powder or lime powder; besides providing calcium, both mainly serve to regulate pH. Gypsum powder, namely calcium sulfate, is slightly acidic and is used to buffer alkalinity; lime powder is light calcium carbonate, is alkaline, and is used to prevent pH from becoming too acidic. The culture medium required for white king oyster mushroom has a pH of 7-8.5, which is on the alkaline side. In addition, bag making is done in late autumn when temperatures are high, so to prevent the culture medium from turning sour, lime powder is preferable. According to green food requirements, additives in the formula must not exceed 5%; 4) Fermentation must be mastered in mechanism. Fermentation uses beneficial microorganisms to naturally catalyze and decompose the culture medium, thereby improving the physical and chemical properties of the substrate, increasing available nutrients, facilitating mycelial absorption, promoting the conversion of as much of the effective components in the culture material as possible into fruiting bodies, and helping to increase yield. During fermentation, 0.3% fermentation agent may be added; the fermentation time is 7 days; after turning the pile 3 times, proceed to bagging, sterilization, cooling and inoculation.
4. Inaccurate grasp of the expected fruiting time
Often because growers are eager for mushrooms, they begin artificial primordium induction before the mycelium is physiologically mature, causing premature and deformed fruiting.
White king oyster mushroom requires "a hundred days of mycelial cultivation for a single day of primordium emergence." For this reason, the "three standards" of mycelial physiological maturity must be mastered: 1) Mycelial age: the cumulative cultivation time from the inoculation date is 90 days; 2) Appearance: the mycelium on the surface layer of the mushroom bag is deep white in color; 3) Substrate feel: firm and hard by hand with slight elasticity, giving a "peng" sound when tapped. Reaching these standards indicates physiological maturity, and at this time it is most suitable to enter the shed, arrange the bags and build the walls.
5. Primordium induction techniques not in place
After the mycelium reaches physiological maturity, it still needs 0-13°C low-temperature stimulation for 10-15 days, and during this period it also needs 5-7 days of temperature-difference stimulation above 10°C, before the primordia can be forced to differentiate into mushroom buds. This is a distinctive characteristic of white king oyster mushroom. Growers often fail to master this unique species trait, with insufficient low-temperature mycelial conditioning and insufficient temperature-difference stimulation, out of harmony with the physiological and chemical requirements of the reproductive period, causing fruiting body development to be inhibited and deformed. Some mushroom growers, when entering the shed in early December to induce primordia, neglect ventilation in order to keep warm, and the shed becomes severely oxygen-deficient; as a result, all the induced mushrooms are "fist mushrooms" with stipes up to 20 cm long and caps tightly clasped and not opening. Low-temperature and variable-temperature primordium induction must achieve the "four coordinations": 1) Open the bags to increase oxygen. Untie the mushroom bags, loosen and twist the bag openings so a tiny amount of air can enter the bags, but do not open the bag mouths completely, to prevent the mycelium from drying out; 2) Scratch the mycelium to awaken it. According to experience in production areas such as **, Beijing and Hebei, after opening the bags, use a small iron rake to scrape away the original spawn block and the surrounding 3.5 cm of aged mycelial skin inside the bag, but do not scratch other parts. Scratching the mycelium helps primordia appear early and positions the fruiting point in the center; 3) Alternate dry and wet. On sunny days, use a sprayer to spray atomized water into the shed space, with relative humidity required at 85%; at night, lift the covering film at the shed edges to allow natural cooling, forming dry and wet stimulation; 4) Introduce scattered light. During the fruiting stage, during the day the straw curtains on the shed roof should be spread thin with 6-10 cm spacing to let sunlight enter. The suitable light intensity is 500-600 Lx, but direct light should be avoided to prevent water evaporation, primordium shriveling, or the mushroom body cracking into flower-mushroom patterns.
6. Thinning of mushroom buds not taken seriously
Some people are overjoyed to see clusters of mushroom buds and, knowing full well the buds are too dense, are reluctant to pick them off. Because thinning is neglected, the fruiting bodies crowd each other, thus producing butterfly shapes, laterally long ox-tongue shapes, hunchback mushrooms and other deformed forms.
Thinning mushroom buds can ensure product shape and quality and is one of the important technical steps in cultivation management. The specific "four requirements": 1) Keep an appropriate number of buds. Each bag generally keeps 1-2, with no more than 3 at most. Too many disperses nutrients, the mushroom body is not thick and fleshy, and quality instead declines; 2) Select buds accurately. Use white color and upright mushroom body as the standard; select the good and remove the poor, keep the large and remove the small, keep the strong and remove the weak, and thin where dense; 3) Operate carefully. Use a sharp knife to cut off excess young buds, without injuring the retained mushroom bodies and mycelium; 4) Protect the buds after thinning. After thinning, pull the bag-mouth film straight and twist it slightly to preserve heat and moisture. Keep the temperature at 13-18°C, not lower than 8°C and not higher than 20°C; the relative humidity of the space should be 85%-90%. The working aisles between mushroom walls should have shallow water storage for moisture retention; and ventilation openings should be opened to keep the air in the shed fresh; at the same time, introduce light and raise the temperature to promote the development of mushroom buds.
7. Poor management during the fruiting stage
After mushroom buds appear, they gradually differentiate into fruiting bodies. During the fruiting stage, poor regulation of temperature, light and air often leads to deformed fruiting body development, lateral growth, or hunchback, or sunken caps, or spotted pockmarked caps, discoloration, and delayed harvesting with oversized fruiting bodies that do not meet grade standards.
During the fruiting period, the "three coordinations" must be done well in management: 1) Coordinate heating and oxygen preservation. The fruiting stage occurs in the twelfth lunar month when north winds blow and the climate is cold; fruiting requires an optimum temperature of 13-18°C. In northern production areas, in addition to introducing light and raising temperature during the day and covering with film to keep warm, at night combustion can be used outside the shed and steam introduced into the shed to raise the temperature. But note that ventilation must not be neglected, to avoid oxygen deficiency causing deformation of the mushroom body; 2) Coordinate humidification and ventilation. During the fruiting stage the relative humidity of the space is required to be 85%-95%. In the dry cold winter, atomized water needs to be sprayed into the space to increase humidity; at the same time, combine this with ventilation, and absolutely avoid spraying "closed-door water" or excessive water, to prevent oxygen deficiency in the shed, or water droplets falling on the mushroom surface and causing water accumulation and rot on the cap that forms a pockmarked face. 3) Coordinate light introduction and moisture retention. During the fruiting stage, scattered light of 500-600 Lx is needed. The straw curtains on the shed roof should be opened 6-10 cm apart to let sunlight shine into the shed, creating an environment of "three parts sun, seven parts shade." But absolutely avoid overly strong light, to prevent water evaporation and mushroom body cracking. Therefore, on sunny days the working aisles between mushroom walls in the shed should maintain shallow water storage, so that after light enters the shed, water vapor rises and increases space humidity; in the morning and evening, spray into the space to increase humidity, but absolutely do not spray onto the fruiting bodies, to prevent mushroom rot or yellowing of the caps.