Control of vine cutting disease of seed sweet potato

Sweet potato vine cutting disease, also known as sweet potato wilt, wilt disease, vine blight and so on.

(pathogen) Fusarium bulbigenum Cke. Et Mass. Var. Botatas Wollenw.

(host crop) sweet potato and other plants of the family Convolvulaceae.

(disease diagnosis) the roots of the diseased seedlings are blue and swollen, the ducts turn brown, and the upper parts are yellow and thin. The disease occurs in adults, the diseased plant is short, the base of the stem is swollen, and there is a halo on the surface. the vascular bundles turn brown after dissection of the diseased plant, extending up to 20 to 30 centimeters from the base of the stem. Except for a few green leaves at the top of the diseased plant, all the other leaves turned yellow, and gradually withered and fell off from the lower old leaves. In the later stage, the cortex of the diseased part was ruptured, showing a fibrous shape, and the epidermis gave birth to pink mildew. When the potato block occurred, the stalk of the potato was rotten, the discolored part of the upper vascular bundle of the diseased potato was cross-cut, and there were black-brown circular spots in the cross section. The pathogen is Fusarium oxysporum from sweet potato. The macroconidium is falcate, the apical cell is slightly pointed, the tip of the terminal cell is slightly curved, and there are 3-5 septum. Small conidia unicellular, ovoid to ellipsoid. Chlamydospores brown, globose.

The pathogen overwintered with mycelia and chlamydospores in diseased potatoes or attached to diseased remains in the soil. Bacteria can also survive in the soil in a saprophytic state. Most of the germs invaded from the wound and spread along the catheter. The incision of the seedling is the main invasive site, and the root wound and leaf scar can also invade. Germs can also invade poorly growing seedlings. The disease can be transmitted by diseased potatoes and diseased seedlings over a long distance, and mainly by soil, running water and agricultural tools. The soil temperature is 27 ~ 30 ℃, and the high soil humidity is beneficial to the disease. Heavy rainfall and heavy rainfall often lead to serious diseases.

(control measures) (1) selection of disease-resistant varieties, such as Chaoshanbai, Nanjing 92, Jinshan 247, Taicheng potato, Nanruili, Jinqing 9, Xuzhou 18, etc. (2) choose disease-free seed potato and raise seedlings in disease-free soil. (3) before planting, the potato seedlings were disinfected by soaking them with 0.2% "401" antibacterial agent for 10 minutes. (4) fully mature manure should be applied. Appropriate amount of irrigation, timely elimination of stagnant water in the field after rain. (5) the rotation of seriously diseased land with food crops for more than 3 years can be effective with rice for 1 year. (6) the diseased plants were pulled out in time, burned or buried deeply. (7) at the initial stage of the disease, it is possible to spray 1500 times of 30% Luyedan wettable powder, 50% carbendazim wettable powder, 40% Shuangxiaoling water agent, or 50% methyl topiramate wettable powder.