Objective This paper studies the control effect of Verticillium wilt of smoke tree (Cotinus coggygria) in Badaling Forest Farm of Beijing by studying the effect of different combinations of chemicals and application techniques, explores effective methods for the prevention and control of Verticillium wilt to ensure the health of C. coggygria and the safety of red leaf landscape in Beijing.

Method We selected five fungicides including Bacillus subtilis, 50% azoxystrobin, 156 g/L propiconazole, 50% carbendazim and 45% prochloraz and set up 12 treatments to control Verticillium wilt in Badaling Forest Farm by injecting root and trunk or a combination of both.

Result Analysis of the 2021 control data showed that the combination treatment 12 (root irrigation of propiconazole combined with trunk injection of carbendazim and azoxystrobin) was most effective, with a corrective disease index of only 5, significantly different from control (P < 0.05) and a corrective control effect of 88%. By comparing the disease indices of each treatment for the period of 2021−2022, it was found that the most effective control combination for that year was root injection of propiconazole combined with trunk injection of carbendazim and azoxystrobin, with a corrected disease index of 5 and control effectiveness was 88%. Moreover, 26.67% of trees in this combination treatment remained healthy and had the highest number of healthy trees. The combination with the lowest disease index in May of the following year was a combination of Bacillus subtilis with root irrigation combined with trunk injections of carbendazim and azoxystrobin, which showed a good treatment efficacy with the highest number of healthy trees, and the severely diseased sample trees from previous years all turned to be healthy or lightly diseased. And the combination had a disease index of only 3.33.

Conclusion This study suggests that the combination of propiconazole in root irrigation and trunk injections of carbendazim and azoxystrobin is most effective, and that the combination of Bacillus subtilis in root irrigation and trunk injection of carbendazim and azoxystrobin performs well in terms of disease treatment and control, both of which can be used as control options for Verticillium wilt.