Carnation white silk disease

Shanghai, Hangzhou.

[symptoms] the disease occurs at the base of the stem near the soil surface and turns brown and rotten; the diseased stem tissue is cut and tea-brown or dark-brown rot develops to the center from the outside; the xylem also changes color upward, and the pinnately radiating white hyphae can spread to the surrounding soil surface; then sclerotia the size of initially white and later yellowish-brown rapeseed is formed on the diseased part and surrounding soil surface mycelia. After the plant is susceptible to disease, the whole plant usually loses and dies. On the cutting bed, wet rot occurs from the healing and forming area of the cuttings, which can also cause serious root neck rot.

[pathogen] the pathogen is a fungus, Sclerotiumrolfsii, sclerotia epiphyte, 0.5 ml 1.0 mm in diameter, smooth and shiny, shaped like rapeseed.

[incidence regularity] the pathogen has a wide host range, which can harm dozens of plants, such as cactus, orchid, squirrel tail, melon leaf chrysanthemum, chrysanthemum, goldfish grass, Persian chrysanthemum, marble chrysanthemum, iris, tulip, hyacinth, lily, Hosta and so on. The pathogen exists as mycelia or sclerotia residues in diseased bodies, diseased plants, wild plants and soil. Shade nuclei can survive in soil for 3-4 years, but the survival time in water and wet soil is very short. High humidity is beneficial to the spread of bacteria, and the disease occurs in summer.

[prevention and control methods]

(1) Horticultural control: avoid continuous cropping with susceptible plants; the base fertilizer should be fully mature to avoid carrying bacteria; proper ventilation to avoid planting too dense.

(2) Pesticide control: disinfect the soil before planting (see Orchid White Silk Disease), or use 50% bacillus, 5 grams per square meter. When the disease occurs during the growing period, the diseased plants should be dug out in time, and the diseased points should be disinfected with lime, or irrigated with 65% Dysen zinc 600% 800 times, or other fungicides. It can also be sprayed or irrigated with 1000 times of 20% EC to control carnation white silk disease.