How to control Sclerotinia root rot of walnut seedlings?

Sclerotinia root rot is also called white silk disease, which damages seedlings for one year, rotting the main root and lateral root cortex, dying the ground, or even all of them. 1. Disease symptoms: At high temperature and high humidity, white silk mycelium was produced at the root neck of seedlings and surrounding soil and on the surface of fallen leaves, and then small sclerotia grew. Pathogen overwinters on diseased plant residues and soil, mostly invades from seedling neck, encounters high temperature, high humidity when the disease is serious, generally starts to occur in late May, June to August is the peak period of disease, seedlings are easy to occur on soil sticky, acidic soil or previous vegetables, grain and other plots. 1) Select nursery land, avoid continuous cropping of disease nursery, select nursery land with good drainage and low groundwater level, adopt high seedbed for cultivation in rainy area 2) Air soil or change soil with sand, change soil once a year, usually 1-2 times effective 3) Seed disinfection and soil treatment, dressing seeds with 50% carbendazim powder 0.3% before sowing, adding lime or plant ash to acidic soil appropriately to neutralize acidity, reducing disease incidence, in addition, The root of diseased tree was irrigated with 500-1000 times solution of 1% copper sulfate or thiophanate-methyl, and the base of seedling neck was sprinkled with hydrated lime, or the soil was irrigated with 1000 times solution of thiophanate-methyl.