Key Technical Points and Cultivation Methods of Log Cultivation of Wood Ear Fungus
As is well known, wood ear fungus can also be cultivated artificially, and the commonly used cultivation technique is log cultivation of wood ear fungus. So what exactly does log cultivation of wood ear fungus involve?
1. Site Selection
Choose a suitable site, generally requiring a wind-sheltered, sunny location, long sunlight hours, and small temperature differences.
In addition, one should choose a place below 1000 m in altitude with little shade, relatively warm conditions, high humidity, abundant tree resources for wood ear cultivation, and close to a water source.
After the site is chosen, it must be cleared. First remove weeds, dead branches, and fallen leaves thoroughly, open drainage ditches, and spread lime and spray dichlorvos on the ground for sterilization and pest control.
2. Selection of Wood Ear Trees
There are many kinds of trees used for cultivating black wood ear fungus, and any tree species that can be used to cultivate shiitake mushrooms can also be used to cultivate black wood ear fungus. The main choices are tree species from the Fagaceae and Betulaceae families, such as sawtooth oak, cork oak, Mongolian oak, white oak, Castanopsis carlesii, and Quercus stewardii; in addition, Chinese wingnut, sweetgum, elm, pagoda tree, willow, mulberry, sycamore, and banyan are also commonly used tree species in production areas.
The tree-cutting period is from after the trees enter dormancy until before new buds sprout. Trees aged 8 to 10 years are suitable. A trunk diameter of 10 to 14 cm is best. After cutting, remove the tips, trim the branches, and saw the wood into logs 1 to 1.2 m long. Stack the sawn logs in a high, dry, ventilated, and sunny place to dry and ferment as quickly as possible. Turn them about once every 10 days to promote even drying of the logs. Generally, after 30 to 40 days of stacking and drying, when the logs are 70% to 80% dry, inoculation can be carried out. If the logs are infected with contaminating fungi or pests, they can be fumigated with thatch or branches before inoculation until the surface bark turns black. This can both eliminate diseases and pests and enhance the bark's heat absorption and water absorption, which is beneficial to the growth of black wood ear fungus mycelium.
3. Cultivation Process
1. Artificial inoculation
Generally, inoculation is done when the air temperature is stable above 15°C, which is favorable for the growth of black wood ear fungus mycelium. The specific time varies with local climatic conditions; in the southern provinces it is about March to April. Properly early inoculation is beneficial for early mycelial growth and early fruiting, and at the same time, early inoculation when temperatures are low can reduce infection by contaminating fungi and pests.
Before inoculation, first clean the surface of the logs, then place them in sunlight for 2 to 3 hours before use. Commonly used spawn types for artificial inoculation include sawdust spawn, branch spawn, and wedge-shaped wooden block spawn. To inoculate with sawdust spawn and branch spawn, use an electric drill or a belt punch 11 to 12 mm in diameter to make holes 15 to 20 cm deep. Generally, the spacing between longitudinal inoculation holes is 10 to 12 cm, and the spacing between transverse inoculation holes is 4 to 6 cm.
If properly densely planted, shortening the spacing between longitudinal inoculation holes to 6 to 7 cm is beneficial for mycelial growth and increasing yield. The holes in adjacent rows should be arranged in a staggered zigzag or plum-blossom pattern. Sawdust spawn should be packed full into the holes, and then covered with a bark lid 2 mm larger in diameter than the inoculation hole, covered flat and tight to prevent the spawn from drying out. When inoculating with branch spawn, the spawn wood should lie flat against the wood ear log. Drilling holes, inoculating, and covering should be carried out continuously to maintain the original moisture of the inoculation holes, spawn, and bark lids, which is beneficial for the survival of the spawn. When using wedge-shaped wooden block spawn, use an inoculation axe or woodworking chisel to cut inoculation openings at a 45° angle and 2 cm deep in the logs, then use a small iron hammer to drive the wedge-shaped wooden block spawn into the inoculation openings, hammering it tight and flat.
2. Stacking for mycelial growth
After inoculation, in order to maintain relatively high temperature and humidity and sufficient air to promote early mycelial growth and early colonization of the spawn in the wood ear logs and increase the survival rate, the wood ear logs must be stacked. The method is to arrange the inoculated wood ear logs into a “well”-shaped rack, stacked layer by layer into a small pile 1 m high, hang dry and wet thermometers inside the pile, cover tightly all around with plastic film, control the pile temperature between 22 and 28°C, maintain the relative air humidity at about 80%, and leave 5 to 6 cm gaps between the wood ear logs for good ventilation. After stacking, turn the pile once every 6 to 7 days, changing the positions of the wood ear logs from top to bottom, left to right, and inside to outside, so that temperature and humidity are uniform and mycelial whitening is even. If the wood ear logs are dry, spray water appropriately to regulate moisture, and after the bark dries slightly, cover again with plastic film. When temperatures are high, uncover the film once every 3 to 5 days at noon for ventilation, combined with spraying water to lower the temperature. Generally, after 3 to 4 weeks of stacking, the black wood ear fungus mycelium has grown into the wood ear logs, and the pile can be spread out and arranged in the field.
3. Spreading the pile and arranging in the field
Spreading the pile and arranging in the field is a continuation of stacking, with the purpose of allowing the mycelium to spread deep into the wood ear logs and rapidly shift from the growth stage to the development stage. The field arrangement site should be sunny and moist, with appropriate shading. When arranging in the field, lay the wood ear logs flat one by one on ground covered with short grass. If the ground is bare soil, first place a small wooden pole horizontally, then place the wood ear logs one by one with their ends on the ground and resting on the horizontal pole, with each wood ear log 6 to 8 cm apart. This not only facilitates absorption of ground moisture and exposure to sunlight, rain, and fresh air, promoting the growth of ear buds, but also prevents all the wood ear logs from sticking to the ground, which could cause excessive moisture, suffocate the spawn, and splash mud onto the wood ear logs. During the field arrangement stage, turn the wood ear logs once about every 10 days and spray water to regulate humidity. After more than a month, when ear buds appear in large numbers, they can be put on racks.
4. Rack management
Racking should be done on a clear day just after rain. Inspect the wood ear logs arranged in the field one by one, and any log with half of its ear buds grown out can be selected and put on the rack. Use four 1.5 m long wooden poles crossed and tied into an “X” shape, place a horizontal beam on top, then lean the selected wood ear logs alternately against the horizontal beam to form a “”-shaped ear shed, with an angle of 30 to 45 degrees, leaving 4 to 7 cm spacing between each wood ear log. Management mainly focuses on coordinating temperature, humidity, light, and ventilation in the ear yard, and especially on water management, maintaining the water content of the logs at about 70% and the relative air humidity between 85% and 95%. Water management should involve both promotion and control, combining promotion with control. The time, frequency, and amount of spraying should be flexibly controlled according to the climate, the wetness of the wood ear logs, and the growth of young ears; generally spray more on sunny days, less or not at all on cloudy and rainy days, and in high temperatures spray daily in the early morning and evening. Using an alternating dry-wet method of spraying is beneficial for the formation and growth of fruiting bodies. After each harvest, stop spraying for 2 to 3 days and let the wood ear logs dry in the sun for a period so they become slightly dry; after the mycelium recovers growth, spray water again to stimulate the formation of the next batch of ear buds.
4. Pest and Disease Control
The contaminating fungi harmful to black wood ear fungus include more commonly black spot disease, leather fungi, polypore fungi, Penicillium, and Trichoderma. Common pests include snails, fungus maggots, thrips, slugs, false walking beetles, and four-spotted ladybird beetles. In control, the policy of “prevention first, integrated control” should be conscientiously implemented. Generally, the following control measures should be carried out well:
1. During tree cutting, branch trimming, log sawing, pile turning, and other processes, try not to damage the bark; disinfect cut ends and wounds with lime water to prevent invasion by contaminating fungi.
2. Select excellent spawn, properly advance the inoculation season, ensure good inoculation quality, and make the black wood ear fungus mycelium dominant in the wood ear logs first, so as to inhibit harm from contaminating fungi.
3. Carefully clean the ear yard, spread lime powder for ground disinfection, and spray 200-times diluted dichlorvos solution to eliminate overwintering pests, so as to cut off sources of disease and insects.
4. If contaminating fungi appear on the wood ear logs, scrape them off promptly to prevent spore spread, wash the wood ear logs with lime water, expose them to strong sunlight for 2 to 3 days, and then spray with Lysol to kill them.
5. Different pesticides should be used for pest control according to different species. For snails and slugs, spray the ground with 300- to 500-times diluted sodium pentachlorophenate to drive them away, or capture them manually in the early morning and evening. Poison bait made from 1:50:50 calcium arsenate plus wheat bran plus water can also be used to trap and kill them. Thrips can be killed by spraying with 15000- to 3000-times diluted dimethoate. False walking beetles can be killed by spraying with 1000- to 1500-times diluted dichlorvos or 0.1% to 0.2% trichlorfon. Four-spotted ladybird beetles can be killed by spraying with derris extract, or the ground can be sprayed with 300- to 500-times diluted dichlorvos to drive away adult beetles.
When mature black wood ear fungus changes color from dark to light; when the ear pieces spread out and soften, the flesh is thick, the base shrinks, and white spore powder is produced on the underside of the fruiting body, it can be harvested.