Orchid nematode control methods and mushroom watering precautions

Nematodes, also called roundworms, are relatively small when parasitizing plants, less than 1mm long. Female nematodes are pear-shaped and males are thread-shaped; they parasitize the roots, leaves, buds and flowers of plants, and often cause damage in low-temperature and dry seasons. The most common nematode diseases in orchids are cymbidium nematode disease in Chinese orchids, root-knot nematode disease in Calanthe, and yellow bud blight in Vanda (which mainly damages inflorescences and commercial flowers). Affected leaves develop yellow or brown patches, causing necrosis, wilting and even leaf drop; affected roots form bead-like nodules or small galls, the small ones like grains of rice and the large ones like pearls, and the white sticky substance inside the galls is the nematode bodies and eggs; affected flower buds dry up and fail to form buds.

The control method is to remove diseased plants or diseased parts, and for the latter they still need to be soaked in hot water at 50-55°C for 5-10 minutes. Because nematodes overwinter in the soil, soil disinfection is also very important; you can drench the soil with a 1000-fold dilution of 40% omethoate or a 100-200-fold dilution of 80% dichloropropane? (emulsifiable concentrate). If the soil is spread out on the ground (8-10cm thick) and exposed to sunlight and dried for 30 days, it can also kill nematodes.