What are the prevention and control methods of tobacco bacterial wilt?

① Select disease-resistant varieties according to local conditions: the first generation of hybrids such as Oxford 26 Duizi1kloc-0/Nanxiong Gengqingtezi 400 and Huangguang 54 Duizi1kloc-0/have strong disease resistance; ② Rotation: 3-5 years rotation, especially with cereal crops, sweet potatoes, soybeans, cowpeas and mung beans; ③ Improvement of field management: transplanting. Keep the soil not too wet to promote the good growth of tobacco roots. Nitrate nitrogen should be used for the proper application of boron fertilizer and nitrogen fertilizer, so as to avoid the application of ammonium nitrogen to find diseased plants, and it should be pulled out, burned or buried in time to avoid diffusion. ④ Chemical control: 200 units of agricultural streptomycin can be used for root irrigation.