Symptoms are also known as wilt disease, culm disease, blight disease, stalk rot and so on. The main damage stems and potatoes. At the seedling stage, the leaves of the main stem of the infected stem turned yellow, and the base of the stem expanded and cracked longitudinally, exposing the medullary part. The vascular bundle became dark brown and the fissured part was fibrous. The potato peduncles in the potato chips were rotten, and the upper part of the diseased potato was cut across. The vascular bundles were brown spots. The diseased plants gradually turned yellow from the bottom and then fell off. Finally, the whole vines dried up and died. Or slightly dark brown spots near the circle, more shallow than the black shank disease, the loss of water around the diseased parts during storage, was dry-like.
The pathogen Fusarium oxysporum f.sp.batatas (Wollenweber) Snyderet Hansen called the special type of sweet potato Fusarium spp. Henan recorded F.bulbigenum Cke.et Mass. var.batatas Wollenw. Also the pathogen of the disease, called Fusarium solani. Large conidia cylindric, slender; small conidiophores, ovoid to elliptic; chlamydospore brown, globose.
Transmission routes and pathogenic conditions The pathogens used mycelia and chlamydospores to infect in diseased potatoes or adhere to soil in the diseased body, becoming the source of infestation at the beginning of the year. The bacteria can survive in the soil for 3 years and invade the wound and spread along the catheter.
Diseased potato and diseased seedlings can be spread over long distances, and close-distance transmission mainly depends on running water and agricultural implements. The soil temperature is 27-30°C, and there are more rainfalls. The rainfall is more conducive to the epidemic. Continuous cropping, sandy land or sandy loam is heavy.
Control methods (1) Selection of disease-resistant varieties such as Nanjing 92, Chaozhoubai, Taicheng, Jinshan 247, Pengwei, Nanshu No. 88, Bengbu and Xuzhou 18 were more resistant to disease. It is forbidden to transfer seeds and seedlings from the ward. (2) In combination with the control of black shank disease, soaking in warm soup, cultivating disease-free seedlings, and soaking with 70% thiophanate-methyl WP by 700 times. (3) Advocate the use of compost or fermented organic fertilizer made from fermented bacteria. (4) Three or more years of rotation for serious wards or fields with rice, soybeans, corn, etc. The diseased plants were found to be removed promptly, buried deep or burned. (5) If necessary, spray 30% Green Leaf Dan WP 800 times or 50% Benomyl WP 1500 times.
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