Pathological Analysis and Control Techniques for Diseases of the Tea Tree Mushroom

The tea tree mushroom (Agrocybe aegerita), also known as the tea mushroom, is a fashionable and rare mushroom variety that has become increasingly popular in domestic and international markets in recent years, emerging as a highlight among cultivated varieties. However, because the mycelium and fruiting bodies of this mushroom contain an almond-like aroma, they tend to attract a relatively high number of pests and diseases. Most of these are caused by infection from pathogenic fungi and insect pests, and are known as infectious diseases. Growers often fail to properly identify the disease symptoms and pathogens, leading to blind application of chemical pesticides. As a result, not only is effective control not achieved, but the mushroom bodies are harmed, product pesticide residues exceed standards, and cultivation returns are poor. Here, the characteristics, pathogens, and control measures of common infectious diseases are described below.

1. Brown rot: Affected fruiting bodies stop growing, and the tissues of the cap, stipe, and gills all turn brown, eventually rotting and giving off a foul odor. The pathogen is Mycogone perniciosa, which mostly occurs on mushroom bags with high water content, and incidence increases at a temperature of 20°C. It mainly spreads through contaminated water or through hands and tools that have come into contact with diseased mushrooms, invading the intercellular spaces of fruiting body tissues to reproduce and cause disease.

Control measures: ① Thoroughly disinfect the mushroom shed, and the substrate must be completely sterilized; ② During the fruiting period, the water used for moisture retention and replenishment must be clean, and ventilation should be strengthened to avoid prolonged exposure to high-temperature and high-humidity conditions; ③ Promptly remove and destroy affected mushrooms, then stop spraying water, increase ventilation, and reduce spatial humidity; ④ Spray mushroom bags with a 1:50 streptomycin solution to kill pathogens hidden inside the bags and prevent disease recurrence during the second flush; ⑤ Harvest mature mushrooms promptly, before the caps have fully opened. Freshly harvested mushrooms should be promptly @#@136@#@ or processed, and storage time in summer should not be too long.

2. Soft rot: Affected caps shrivel, the gills and stipe become hollow, bend and collapse softly, and eventually die and become rigid and shrunken. The pathogen is Fusarium solani, which erodes fruiting body tissues and forms a grayish-white moldy layer, which consists of some conidiophores and conidia. This pathogen is normally widely distributed on various organic materials. Airborne conidia cause high incidence under high-temperature and high-humidity conditions, and severe infection results in reduced yields.

Control measures: ① Sun-dry raw materials; when preparing the substrate, the water content should not exceed 60%; after bagging, sterilize thoroughly; ② Inoculate at midnight when temperatures are low, with strict aseptic technique; ③ Before opening the bags to induce primordia, spray with 50% dichlorvos emulsifiable concentrate at 1000x dilution for sterilization; after opening, maintain an optimal temperature of 23-25°C and a relative humidity of 80%; ④ If disease occurs at the young mushroom stage, spray with lime supernatant at pH 8, or use low-toxicity 20% triadimefon emulsifiable concentrate at 1500x dilution for spray control. If this disease occurs at the mature mushroom stage, harvest early and soak in 5% lime water, then wash the product with clean water and dry it.

3. Damping-off: Infected mushroom stipes shrink and dry up, fail to develop, and wilt, but do not rot, reducing yield and lowering quality. The pathogen is Fusarium solani. It is mostly caused by poor-quality substrate materials, such as cottonseed hulls, sawdust, wheat bran, and other raw and auxiliary materials that are caked, moldy, and mixed in; prolonged loading and sterilization time leads to acidification of the base material; incomplete sterilization of substrate bags allows pathogens to hide within the substrate, becoming active when temperatures exceed 28°C.

Control measures: ① Optimize the base material; cottonseed hulls, wheat bran, and other raw and auxiliary materials should be fresh, without caking or mold; ② The time from bagging to sterilization in the cooker should not exceed 6 hours; after reaching 100°C during sterilization, maintain for 16-20 hours; ③ During mycelial culture, prevent high-temperature burning of the mycelium; keep the room dry, moisture-proof, and protected from direct sunlight; ④ Open the bags at the appropriate time to increase oxygen and promote smooth formation of primordia into fruiting bodies. Maintain the fruiting temperature at 23-28°C and relative humidity at 85%-90%; ⑤ If disease occurs during the fruiting body development stage, harvest early, promptly scrape away the affected substrate, and spray with 75% chlorothalonil at 1500x dilution. After resting and culturing the mycelium for 2 days, spray water to increase humidity and promote continued mushroom growth.

4. Black spot: Affected fruiting bodies develop black spots distributed on the cap and stipe, with a marked contrast in the color of the mushroom body. In mild cases, it affects the product's appearance; in severe cases, it leads to mold. The pathogen is Cephalosporium sp., which mainly spreads through air, wind, rain, and mist; it is often transmitted through contact with the hands, body, and tools of workers; when the mushroom house temperature is 25-30°C, ventilation is poor, and excessive water spraying causes liquid water to accumulate heavily on the mushroom bodies, this disease is prone to occur.

Control measures: ① Keep the mushroom house clean and sanitary, with good ventilation, preventing high temperature and high humidity; ② After inoculation, culture the mycelium at the appropriate temperature, strengthen ventilation, and allow the mycelium to fully colonize normally; ③ During the fruiting stage, follow the principle of light, frequent, and fine water spraying, and ventilate promptly after each spraying; ④ If affected at the young mushroom stage, spray once with 20% triadimefon emulsifiable concentrate at 1500x dilution; if disease occurs in mature mushrooms, promptly remove them, dig out the surrounding contaminated areas, and spray with Xinzhi Meidu at 4000x dilution, or spray with 5% iprodione wettable powder at 1000x dilution.

5. Mold rot: Affected fruiting bodies become moldy and black, collapse and rot, and give off an ammonia-like odor. It spreads quickly and, in severe cases, causes an entire batch to rot and result in reduced yields. The pathogen is Trichoderma viride, which erodes the surface layer of fruiting bodies. Initially it is pinkish-white, gradually turning green and then ink-black, until it becomes mushy and moldy-smelling. It is mostly caused by incomplete sterilization of substrate bags, with pathogens lurking within the base material, becoming active during fruiting and transferring from the mycelium to the fruiting bodies. At the same time, relatively high humidity in the mushroom house and poor ventilation favor its spread, and affected mushrooms lose their commercial value.

Control measures: ① Thoroughly clean the environment around the inoculation room, culture room, and fruiting shed. Within a distance of about 30 m around the mushroom shed, spray a mixed solution of 400x carbendazim and 200x phenol. When the pathogen population is relatively high, spray 100x phenol solution inside the mushroom shed, and keep it sealed for 2 days before use. ② The water content of substrate bags should not exceed 60%, and they should be thoroughly disinfected so that pathogens have no place to hide. ③ Strictly follow aseptic technique during inoculation, and spray fungicide in the culture room once every 5 days. Alternately use 150x Junjuesha and 200x phenol. ④ After disease occurs, move diseased bags out for burning or deep burial. Alternatively, use 50x Baibing Quwuzong solution, soak the bags, then crush them, pile them for fermentation, and use them as organic fertilizer.

6. Withering disease: This often occurs shortly after primordia appear, causing them to wither and die without differentiating into fruiting bodies, affecting the harvest of one flush. Its pathogen is damage caused by nematodes, small worm-like organisms. It often occurs during plum rain, muggy conditions, and poor ventilation. Nematodes pierce into the mycelium with their needle-like mouthparts, suck out cell fluid, causing mycelial decline and an inability to supply nutrients and water for primordium growth and differentiation, resulting in death. Sometimes they also directly feed on primordia and young mushrooms, causing the fruiting bodies to lose the ability to grow and develop and wither.

Control measures: ① Disinfect the mushroom house and all tools in advance so that nematodes have no conditions to survive. ② For the substrate, first pile it for fermentation, then bag and sterilize it. ③ During mycelial culture, pay attention to temperature control, preferably not exceeding 28°C. When temperatures are high, promptly spread out bags to dissipate heat; open doors and windows fully at night for all-night ventilation to lower pile and bag temperatures, cultivate a strong mother culture, and increase stress resistance. ④ Open the bags at the appropriate time to increase oxygen, promote normal mycelial metabolism, and ensure the timely transition from vegetative growth to reproductive growth for good fruiting. ⑤ During the young mushroom stage, spray water lightly and frequently, not excessively, to prevent water accumulation. At the same time, pay attention to ventilation and create suitable environmental conditions. Promptly remove affected ones, scrape away the surface layer, stop spraying water for 2 days to let the mycelium recover, then spray an appropriate amount of water to promote renewed mushroom growth.

7. Hollow sore disease: During the fruiting body formation stage, hollow sores from bites or insect damage often appear, causing loss of commercial value. The main pathogenic pests include small mushroom gnats, phorid flies, and purple springtails. These pests are mostly caused by garbage piled randomly around the mushroom shed and overgrown weeds, which provide parasitic breeding conditions for pests; combined with incomplete pest-proof facilities in the mushroom house, pests can fly in unimpeded.

Control measures: ① Maintain good sanitation in and around the mushroom house, and disinfect with lime to cut off pest sources. ② Install 60-mesh screens on doors, windows, and ventilation holes to prevent adult insects from flying in, and regularly spray the screens with plant-based insecticide Chuchongjun or 2000x Yitaibao solution. ③ Install black light lamps indoors for trapping and killing, or place half a basin of 0.1% 7051 insecticidal emulsion under the indoor light. Adhesive can also be applied to wooden boards and hung near the light to trap and kill invading pests. ④ Control pesticide use; when absolutely necessary, spray with low-toxicity, low-residue 3000x fipronil solution or 2000x Nongmengte solution for control.