Control of Cymbidium mosaic virus disease and edible mushroom cultivation techniques

Cymbidium mosaic virus disease, also known as necrotic mosaic disease, black streak necrosis disease, etc., is caused by infection with Cymbidium mosaic virus (CyMV) and Tobacco mosaic virus (TMV), and is the most common of the viral diseases affecting Cymbidium. Both Cymbidium mosaic virus and Tobacco mosaic virus have extremely wide host ranges, including plants of more than 70 genera such as Cymbidium, Calanthe, Dendrobium, Paphiopedilum, and Vanda, and they are stable in nature, usually surviving for a long time in the sap of diseased plants.

Therefore, when orchids are repotted and transplanted or propagated by division, once a plant is diseased, the virus is transmitted to other plants through contaminated sap on tools and substrate, and enters healthy orchid cells through wounds to cause infection; household orchid growing is often limited by space, with plants placed too densely and leaves frequently overlapping and pressing against each other, so that when affected by external forces (such as wind, watering, sprinkler irrigation, or handling), the leaves rub against one another, increasing the chance of injury, and the virus can also invade and infect through the wounds thus created; some growers also use vertical shelving arrangements to save space, and the excess water seeping from the upper tier when watering naturally splashes onto the plants on the lower tier, causing the virus to spread everywhere and then invade through wounds.

Affected orchid plants often show varying symptoms depending on the growing environment, usually with long strip-like necrotic tissue appearing on the lower surface of the leaves, causing leaf death, but the flowers may show no symptoms. About 3 weeks after infection, irregular yellow spots appear on new shoots, becoming increasingly obvious and numerous as the leaves grow, then turning into brown or grayish-brown necrotic spots. Some cultivars after infection show rectangular, yellowed broken lines that then turn black and necrotic, and the black necrotic areas may also spread across the entire leaf.

Cymbidium mosaic virus disease, like other plant viral diseases, has no effective control method at the current level of technology, so in ordinary times one should pay attention to observation, and once a suspicious plant is found, it should be immediately isolated or burned. Improve environmental sanitation, disinfect tools, and regularly spray insecticides (for aphids) to prevent its spread. Currently commonly used disinfectant solutions include 2% formalin and 2% sodium hydroxide aqueous solution, both of which have good effects. For tool and environmental disinfection, a disinfectant solution prepared by adding 164 g of anhydrous or 337 g of crystalline sodium phosphate to 1000 mL of water can be used. Ordinarily, do not buy virus-carrying seedlings or suspicious virus-carrying seedlings, and even more do not obtain explants from diseased plants or suspicious virus-carrying plants for tissue culture. If conditions permit, it is best to also carry out virus testing on the mother plants from which material is taken, and use them only after confirming there is no viral infection.