Effects of three different soil fumigation on control of soil-borne diseases and agronomic traits of flue-cured tobacco

Yunnan is the main planting area of tobacco in China. With the increase of continuous cropping years, pathogenic organisms accumulate in soil year by year, and soil-borne diseases become more and more serious, which become an important obstacle factor restricting the sustainable development of tobacco planting. Combine the plant species planted in Kunming tobacco field in spring which is harvested before transplanting tobacco seedlings, the effects of chemical, biological and combined chemical and biological fumigation techniques on the prevention and control of soil-borne diseases and yield of flue-cured tobacco were studied for the first time.The killing rates of the four representative pathogens of soil-borne diseases by 375 kg/ hm² dazomet treatment, biological mustard fumigation treatment, 150 kg/ hm² dazomet combined with mustard were, respectively, 97.51%, 45.09%, 80.27% for phytophthora, 97.56%, 48.63%, 72.14% for pythium, 95.51%, 55%, 72.14% for fusarium, 93.99%, 65%, 83.18% for root knot nematode; the prevention and control rates of four soil-borne tobacco diseases were, respectively, 88.10%, 66.93%, 78.44% for black shank, 91.05%、71.90%、85.03% for black root rot, 91.05%、64.78%、74.42% for root knot nematode disease, 61.30%、43%、57.33% for bacterial wilt; the stem diameter, leaf number, leaf length and leaf width of the three fumigation treatments increased positively, and the yield of flue-cured tobacco was 1.79 times, 1.26 times and 1.52 times that of the control , respectively. The results showed that the three fumigation treatments had a certain effect on the prevention and control of soil-borne diseases and yield increase of flue-cured tobacco, and effect of dazomet were the most significant, and the effect of combined was between dazomet treatment and mustard treatment. Dazomet and mustard fumigation is a new and effective pesticide reduction technology. In production, different fumigation and disinfection methods can be adopted according to the number of phytophthora, rot, fusarium and root-knot nematode in different tobacco planting soil.