Detailed Explanation of Autumn and Winter Cultivation of Edible Fungi and Pest Control Methods
Recently there have been many inquiries about pest problems in autumn-cultivated edible fungi. Through on-site investigations, it was found that pest damage to edible fungi has been relatively severe this autumn. Some mushroom sheds have almost become "pest sheds," and the pest damage has triggered a large amount of weed mold contamination and serious diseases, causing heavy losses for mushroom growers. Today, based on the investigation results, an expert has been invited to introduce to mushroom-growing friends the "prevention" and "control" of pests in autumn and winter seasons, in order to reduce losses for mushroom growers.
Types of Pest Occurrence and Identification
1. Mushroom gnats and mushroom flies: Autumn cultivation generally uses fermented substrate, such as oyster mushrooms, shaggy ink cap mushrooms, and button mushrooms. Smaller mushroom gnats, oyster mushroom eye gnats, mushroom eye gnats, spiny eye gnats, heterogeneous eye gnats, dung flies, phorid flies, fruit flies and other adults lay eggs near the substrate. Adults and eggs cannot directly cause harm; when the temperature is between 16°C and 30°C, eggs hatch into larvae in about 4 days. Larvae feed on mycelium or fruiting bodies, causing damage for about 7 to 18 days before pupating. The pupal stage generally lasts about 2 to 8 days, after which they emerge as adults. After emergence, adults can mate again on the same day or the next day, and can lay eggs on the day of mating. Generally, each mushroom gnat lays more than 10 eggs, with the maximum reaching 270 eggs. Mushroom gnat adults are relatively large in body size; general varieties can have a body length of over 3.5 mm, with the largest exceeding 6 mm. Larvae generally have a body length of about 5 mm, with the largest exceeding 16 mm. Mushroom flies are smaller in body size; the largest phorid fly adults have a body length of only about 1.5 mm, while larvae are between 2 mm and 3 mm. However, fruit fly adults and their larvae can reach a body length of about 5 mm, similar to mushroom gnats.
The adults of the above pests are highly phototactic and odor-tropic (mushroom aroma, substrate aroma, decay odor). When mushroom sheds are kept in darkness, the occurrence rate is relatively low, and pest population density is greatly reduced. Their larvae initially move about in the surface layer of the substrate, biting and eating mycelium. After mushrooms emerge, they can bore to the base of the stipe, and even to the cap. After the mushroom body becomes "hollow," they return to the substrate and continue to cause damage deeper, until all mycelium in the substrate is completely consumed.
2. Mites: Mites have many sources. They may reside in cracks in the corners of sheds, survive in gaps between support columns, cracks in bamboo and wood of shelf poles, enter mushroom sheds through various tools, and some can even be transmitted through spawn (mainly third-generation spawn). In short, there are many entry routes. Mites mainly cause damage by biting and eating mycelium, but when population density is high, they can also bite mushroom buds and mature fruiting bodies. The main mite varieties include flour mites, straw itch mites, and ear mites. Mites are extremely small in size, but they have gregarious habits, moving about in groups and clusters on the substrate surface and in shed corners and on the ground. When population density is very high, the substrate surface appears white (dirty white) or flesh-red, or even reddish-brown.
Mites reproduce extremely quickly. At temperatures of 20°C to 30°C, completing one generation requires about 8 days, and some varieties require only 3 days to complete one generation. Depending on the variety, some mites also go through egg, larval mite, nymph mite, and adult mite developmental stages, but some varieties only have eggs and mites, because their eggs can develop directly into adult mites within the mother's body and then emerge by breaking through the body. When living conditions are unsuitable, or when there is no fungus or mushroom available for food, they can attach to tools, human bodies, or even other living insects, and transfer to suitable locations to continue their survival and reproduction.
3. Springtails: These pests mostly cause damage in summer and autumn. They can survive at temperatures above 15°C, gradually become active when the temperature reaches 22°C, and then reproduce and expand. Springtails feed on mycelium and fruiting bodies, and lurk in gill folds and tiny cracks, greatly reducing product value or even making it worthless. There are many springtail varieties, with common ones mainly including horned springtails, black horned springtails, and black flat springtails. Springtails have very long lifespans; most varieties can survive for about half a year, with the longest reaching one year. The main morphological characteristic of springtails is their tiny body size, generally about 1.5 mm, with the largest being under 5 mm. The humid environment, dim light, abundant mycelium and mushroom nutrition in mushroom sheds provide the best conditions for springtails to reproduce and thrive, therefore their harmfulness is relatively great.
4. Nematodes: Nematodes mainly harm edible fungus mycelium. There are also multiple varieties, mainly including mycelial nematodes with stylets and small rod nematodes without stylets. The former insert their stylets into mycelium to suck mycelial fluid, causing mycelial growth to be blocked and then to shrink and die, producing a "mycelium recession" phenomenon; the latter rapidly stir mycelium with their heads, breaking it into extremely fine fragments, then swallow or suck them, with the same result of mycelium disappearing. Nematodes are tiny in body size, generally about 1 mm, but their reproduction speed is very fast. Generally at 20°C to 30°C, eggs can be laid about 30 hours after mating. One female can lay dozens of eggs, with the maximum reaching 140 eggs; eggs develop to adults in only about ten days, and at temperatures above 25°C, only about 8 days are needed. Nematode pests have smooth body surfaces and prefer water-soaked environments or conditions with relatively high moisture. When moving, they appear like a mass of water moving, which is an important method for identifying nematodes.
In autumn production, there are other pests or small animals that can cause a certain degree of damage, such as snails, woodlice, and mole crickets. Preventing pest damage is a proactive attitude in pest control during edible fungus production, and the effect is excellent. The main measures are: During the substrate composting stage: First, using insect-proof nets to prevent insects from laying eggs near the substrate is an economical, effective, and simple top measure, while also effectively solving the problem of pesticide residues. Using ordinary insect-proof nets used in vegetable breeding is sufficient; even tiny mushroom flies cannot get through. Second, frequently spraying high-efficiency, low-residue drugs on the substrate surface to repel insects, but the concentration used should be low and the spray amount should be small, to avoid pesticide residues. Third, when conditions permit, try to use sterilized substrate cultivation methods, which prevent insects while also eliminating weed molds and pathogens, achieving multiple benefits at once. Finally, when cultivating button mushrooms and Himematsutake mushrooms, promote and apply the secondary fermentation technique. Temperatures as high as above 60°C lasting for about 2 days will kill all living insects including eggs, larvae, and adults. Although production costs increase slightly, it brings many effects such as killing insects, killing (inhibiting) bacteria, uniform substrate decomposition, and removing odors, achieving multiple benefits at once.
During the spawning and mycelium-running stage: A considerable number of pest infestations invade at this stage. The mycelium-running stage generally lasts about 3 to 5 weeks. Oyster mushroom, shaggy ink cap mushroom and other fungus bags are all perforated with micropores, which can fully satisfy the entry and exit of mushroom gnats and mites with basically no restriction. First, seal the doors, windows, and ventilation openings of the mycelium-running room with high-density window screens (such as insect-proof nets), and persist in dark cultivation to prevent adults from entering due to phototaxis. Second, frequently check whether there are adults indoors. Once found, immediately spray low-concentration pyrethroid drugs to kill them. Even simply spraying clean water so that mushroom gnat wings get water droplets on them can cause adults to fall to the ground and be unable to fly again, also causing death. Finally, when the surrounding environment of the culture room is poor, for example near garbage, stables and latrines, or manure piles, in addition to cleaning and preventing as much as possible, frequently spraying insecticide in the space and on walls indoors is also a very powerful preventive measure. During the mushroom fruiting management stage: First, seal the doors, windows, and ventilation openings of mushroom sheds with high-density window screens (insect-proof nets are sufficient) to prevent adults from entering. Second, reduce the light inside the shed as much as possible. Third, insist on using well water or tap water for management water, not "dead water" from ditches, bays, or ponds. Fourth, spread a 1 m to 2 m wide lime belt on the ground at entrances and exits to prevent mites, woodlice, and other pests and small animals from entering. Finally, during the interval between fruiting flushes, spray appropriate amounts of pyrethroid drugs, combined with formaldehyde and bleaching powder drugs, which has the dual effect of preventing both insects and bacteria. However, during the growth of fruiting bodies, any drugs should be prohibited to prevent pesticide residues from affecting quality.
Sources of pests: In edible fungus cultivation production, most pests enter the substrate in the form of eggs. A small portion lay eggs in the substrate before spawning, while most lay eggs after spawning. The probability of entering the spawning stage through spawn carrying live larvae (or live insects) is relatively small. Egg hatching proceeds simultaneously with substrate mycelium running. Under normal circumstances, it is impossible to detect or identify with the naked eye; initially, individual larvae and groups are both small, and the amount of mycelium consumed is very small, not easily noticed. When larvae continue to develop and grow, and as the population expands, damage to mycelium becomes more severe, it is already at the first fruiting flush or entering the peak fruiting period. At this stage, it is still difficult to detect, until the second fruiting flush becomes difficult, or even no more mushrooms are produced, and the mycelium on the substrate surface has nearly disappeared and turned brown, only then is it discovered that pests were the culprit. It can be said that quite a number of producers discover pests at this stage. Another characteristic of pests in autumn and winter is that as temperatures gradually decrease, insects are also looking for warm shelters. The inside of the substrate is relatively suitable, and the temperature in culture rooms and cultivation sheds is also relatively suitable. After finding a suitable "residence," they rapidly reproduce, causing the pest population to expand rapidly.
Damage symptoms: Pests occurring on edible fungi all feed on mycelium during the early mycelium-running stage, and during the later fruiting stage they "eat everything" including fruiting bodies. When infestation is severe, the substrate surface changes from white to yellow, to brown, or even becomes black, with pest excrement densely distributed on the surface and even inside. The base of fruiting bodies and even the entire stipe are bitten into a sponge-like state, and even mushroom caps have insect holes. On the other hand, pest damage can lead to the rampant spread of certain diseases or weed molds. For example, when mycelium on the substrate surface disappears and insect excrement is everywhere, causing rot, weed molds such as Trichoderma and Rhizopus take the opportunity to invade, easily causing diseases; insects biting fruiting bodies causes young mushrooms (mushroom buds) to die and rot, and also easily attracts external adults to enter. Insect bodies carry various bacteria or fungi, and while increasing pest (population) density, they also bring in a large amount of pathogens, making the already damaged edible fungus production "even worse."
Methods for killing pests: Timely discovery of pest damage and taking measures to kill them should strictly select drug varieties, paying attention to both pesticide residue issues and preventing phytotoxicity. When initial pest density is extremely small, using high-efficiency low-residue pyrethroid drugs, spraying in the air or on the substrate surface casing soil is sufficient to kill them.
When occurrence is moderate, some eggs will be laid inside the substrate. Fruiting bodies can be harvested all at once. For mushroom gnats and springtails, use 800-fold DDV to spray the substrate surface and casing layer, and cover with plastic film for 3 to 5 hours; for mite pests, spray 1000-fold acaricide drugs, such as saomante and shamandol, also covering with plastic film for several hours; for nematodes, use 0.5% formaldehyde solution for heavy spraying, also covering with plastic film for 2 to 4 hours.
When brown patches appear on the substrate surface and insect bore holes appear on stipes, it is already a severe occurrence. At this time, larvae are mostly inside the substrate, and spraying drugs is generally ineffective. Aluminum phosphide "total kill" measures can be used to kill all at once. The method is: harvest all fruiting bodies. For mushroom wall cultivation, use plastic film to cover the mushroom wall, place one piece of aluminum phosphide at 1 m intervals on both sides, quickly compact the surrounding edges of the plastic film with soil, and about 8 to 10 hours is sufficient. For pest killing in mushroom bed cultivation methods, refer to the above. Key points to note: Operations must be fast; the film covering must be compacted; when removing the film, first open the mushroom shed doors, windows, and ventilation openings. Then lift the plastic film, and after 1 to 2 hours, move the plastic film outside the shed, carefully pick out the aluminum phosphide waste material, and bury it deeply. It must not be discarded carelessly.