What are the control methods for southern blight in orchids?

Southern blight is caused by the fungus Selerotiumrolfsii, which harms the stem base and roots from seedlings to mature plants, and Cymbidium hybridum is more susceptible to this disease. When the disease occurs, white mycelium can be seen at the stem base, the stem base turns brown, the roots dry up, and a large number of small brown sclerotia form, causing the plant's stem base to soften and die. This pathogen has a very wide host range and causes more serious damage to bulbous flowers and perennial flowers. It also has strong saprophytic ability and can survive for a long time in the substrate or old pots through sclerotia. This fungus can also infect the roots and leaves of Phalaenopsis plants, causing root rot or soft rot of the leaves. In seedlings, the early symptoms are not easily distinguished from soft rot or phytophthora disease in appearance, but soon afterward the unique white mycelium of southern blight grows on the affected parts and substrate, and later turns into brown sclerotial granules. The prevention methods are as follows:

(1) Do not use old seedling trays and substrate that have not been disinfected.

(2) Clear away other hosts and maintain good environmental sanitation in the orchid garden.

(3) Patrol the garden, pick out diseased plants and diseased leaves, remove them and burn them.

(4) When the disease occurs frequently, 50% Fudoning or 75% Miepuning wettable powder can be sprayed.