Detailed Explanation of the Key Points of Log Cultivation Techniques for Wood Ear Mushrooms

1. Site Selection

Choose a suitable site, generally requiring shelter from the wind and facing the sun, 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 wood ear tree resources, and close to a water source.

After the site is chosen, it must be cleared. First remove weeds, dead branches, and fallen leaves completely, 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 mushrooms, and any tree species that can be used to cultivate shiitake mushrooms can also be used to cultivate black wood ear mushrooms. The main choices are tree species from the Fagaceae and Betulaceae families, such as sawtooth oak, cork oak, oriental white oak, white oak, Castanopsis carlesii, and Quercus huaensis; in addition, Chinese wingnut, sweetgum, elm, pagoda tree, willow, mulberry, plane tree, and banyan are also commonly used tree species in production areas.

The period for felling trees is from after the trees enter dormancy to before new buds sprout. Trees aged 8 to 10 years are suitable. A trunk diameter of 10 to 14 cm is best. After felling, remove the top, strip the branches, and cut into logs 1 to 1.2 m long. Place the sawn logs on racks to dry in a high, dry, ventilated, sunny place so they 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 rack drying, when the logs are 70% to 80% dry, inoculation can be carried out. If the logs are infected with contaminating microorganisms or pests, they can be smoked and burned with thatch or branches before inoculation until the surface turns black. This can both remove diseases and pests and enhance the bark's heat absorption and water absorption performance, which is beneficial to the growth of black wood ear mushroom mycelium.

3. Cultivation Process

1. Artificial inoculation

Generally, this is done when the air temperature is stable above 15°C, which is favorable for the growth of black wood ear mushroom 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 at low temperatures can reduce infection by contaminating microorganisms 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 inoculum for artificial inoculation includes sawdust spawn, branch spawn, and wedge-shaped wood block spawn. For sawdust and branch spawn, use an electric drill or a belt punch 11 to 12 mm in diameter to make holes, with 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 appropriately close planting is used, 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 are arranged alternately in a pinwheel or plum-blossom pattern. Sawdust spawn should be packed full in 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. For branch spawn, the spawn wood should lie flat against the wood ear log. Hole punching, inoculation, and covering should be carried out as continuous operations 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 wood block spawn, use an inoculation axe or carpenter's 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 wood block spawn into the inoculation openings, hammering 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” shape, stack them layer by layer into a small pile 1 m high, hang dry and wet thermometers inside the pile, cover tightly around with plastic film, control the pile temperature between 22 and 28°C, maintain 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 consistent and mycelial whitening is uniform. If the wood ear logs are dry, appropriately spray water to adjust, and after the bark dries slightly, cover again with plastic film. When the temperature is high, uncover the film once every 3 to 5 days at noon for ventilation, and combine this with spraying water to lower the temperature. Generally, after 3 to 4 weeks of stacking, the black wood ear mushroom mycelium has grown into the wood ear logs, and then the pile can be broken up and the logs laid out.

3. Breaking up the pile and laying out the logs

Breaking up the pile and laying out the logs is a continuation of stacking. Its purpose is to allow the mycelium to spread deep into the wood ear logs and to rapidly shift them from the growth stage to the development stage. The site for laying out the logs should be sunny and moist, with appropriate shade. When laying them out, place the wood ear logs flat one by one on ground with short grass. If the ground is bare soil, first lay 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 to promote ear bud growth, but also avoids having all the wood ear logs stuck to the ground, which could cause excessive moisture, smother the spawn, and splash mud onto the wood ear logs. During the laying-out stage, turn the wood ear logs about once every 10 days and spray water to regulate humidity. After more than a month, when a large number of ear buds appear, they can be put on racks.

4. Rack management

Racking should be done in weather that is clear just after rain. Check the laid-out wood ear logs one by one; 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, cross-bind them 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, leaving 4 to 7 cm spacing between each wood ear log. In management, the main focus is coordinating temperature, humidity, light, and ventilation in the ear yard, especially water management. The moisture content of the logs should be maintained at about 70%, and the relative air humidity should be controlled between 85% and 95%. Water management should both promote and control, combining promotion with control. The time, frequency, and amount of spraying should be flexibly controlled according to climate, the wetness of the wood ear logs, and the growth of young ear bodies. Generally, spray more on sunny days, less or not at all on cloudy and rainy days, and spray every morning and evening when the temperature is high. Using alternating dry and wet methods for spraying is beneficial for the formation and growth of fruiting bodies. After each harvest, stop spraying for 2 to 3 days, let the wood ear logs dry in the sun for a period so they become slightly drier, and 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 more common contaminating microorganisms harming black wood ear mushrooms include black spot fungus, corticioid fungi, polypores, Penicillium, and Trichoderma. Common pests include snails, fungus gnats, thrips, slugs, false ground beetles, and four-spotted leaf 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 felling, branch stripping, sectioning, pile turning, and other processes, try not to damage the bark. Cut ends and wounds should be disinfected with limewater to prevent invasion by contaminating microorganisms.

2. Select excellent spawn, appropriately advance the inoculation season, and strictly control inoculation quality so that black wood ear mushroom mycelium first dominates in the wood ear logs and thereby suppresses the harm of contaminating microorganisms.

3. Carefully clean the ear yard, spread lime powder for ground disinfection, and spray 200-fold dichlorvos solution to eliminate overwintering pests, so as to cut off sources of disease and insects.

4. If contaminating microorganisms appear on the wood ear logs, scrape them off promptly to prevent spore spread, wash the wood ear logs with limewater, expose them under 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-fold sodium pentachlorophenate to drive them away, or hand-catch them 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 sprayed with 15000- to 3000-fold dimethoate. False ground beetles can be sprayed with 1000- to 1500-fold dichlorvos or 0.1% to 0.2% trichlorfon. Four-spotted leaf beetles can be sprayed with rotenone, or the ground can be sprayed with 300- to 500-fold dichlorvos to drive away adults.

When mature black wood ear mushrooms change color from dark to light; when the ear pieces spread out and soften, the flesh becomes thick and the ear base shrinks, and white spore powder is produced on the ventral surface of the fruiting body, they can be harvested.