Detailed Explanation of Control Methods for Root Rot in Atractylodes macrocephala

Symptoms: The fine roots in the lower part of the diseased plant turn brown and rot, then spread to the upper fleshy rhizome and stem, showing dark brown sunken rotting spots, and the aboveground part begins to wilt. On the cut surface of the rhizome and stem, the vascular bundles show an obvious discoloration ring, and in the later stage the entire rhizome becomes spongy black dry rot, the plant dies, and it is easy to pull out of the soil. It occurs commonly in both new and old production areas, causing dry rot, stem rot and wet rot, seriously affecting yield and quality.

Pathogen and occurrence pattern: The pathogen is mainly Fusarium oxysporum Schl., and it has been reported to be caused by complex infection by multiple Fusarium species. Soil-borne inoculum in diseased residues is the source of infection of the disease; during storage of planting material, heating reduces the disease resistance of seedlings, which is the main cause of disease occurrence. Soil flooding, heavy clay texture or application of undecomposed organic fertilizer causes poor root development, and wounds caused by nematodes and underground pests make the disease more likely to occur. If continuous rainy weather is followed by clearing and rising temperatures in the middle and late growth stages, the disease occurs severely. June to August is the peak period of disease occurrence.

Control methods: 1. Choose sandy loam soil with high, dry terrain and good drainage for planting, and cultivate shallowly to avoid root injury; strengthen the control of underground pests and nematodes. 2. Practice rational crop rotation, and select to plant short-stemmed broad-leaf varieties with relatively strong disease resistance; select robust, disease-free planting material as seed, and keep the planting material fresh and alive during storage to prevent it from losing water and shrinking after heating. 3. Pull out diseased plants early, and drench the diseased holes with 50% carbendazim or 70% thiophanate-methyl 800-fold solution; before planting, soak the planting material in 50% carbendazim 500-fold solution for 6 to 8 minutes, remove it, dry it, and then plant.