烟草青枯病菌对4种杀菌剂的敏感性及复配药剂联合毒力评价

为筛选出对烟草青枯病菌具有抑制作用的高效药剂，以链霉素为对照，采用生长曲线测定仪检测了烟草青枯病菌对氟啶胺、双苯菌胺、噻霉酮和春雷霉素的敏感性，并利用Wadley方法对氟啶胺与纳米硫、纳米铜、纳米银的9种复配比例进行联合毒力评价。结果表明，双苯菌胺和氟啶胺对烟草青枯病菌的平均EC₅₀分别为0.037 8 μg/mL和0.305 0 μg/mL，EC₅₀分布范围分别为0.018 7~0.053 4 μg/mL和0.147 1~0.890 4 μg/mL，链霉素、噻霉酮和春雷霉素对烟草青枯病菌的平均EC₅₀分别为0.546 3 μg/mL、2.429 9 μg/mL和9.927 3 μg/mL，说明杀真菌药剂氟啶胺、双苯菌胺可有效抑制青枯病菌生长，且抑菌效果优于链霉素等药剂。5种药剂对烟草青枯病菌的敏感基线均呈正态分布，为连续的单峰曲线，可用于田间烟草青枯病菌抗性菌株监测。氟啶胺与纳米农药按不同比例复配后的EC₅₀均小于纳米农药单剂的EC₅₀。当氟啶胺与纳米硫按体积比1 ∶ 40复配时具有增效作用，增效系数为1.60；氟啶胺与纳米铜按体积比80 ∶ 1复配时，相加作用最为明显（EC₅₀=0.142 2 μg/mL）；氟啶胺与纳米银的复配比例（体积比）为1 ∶ 20时，增效系数最高达1.41，具有相加作用。 

Sensitivity of Ralstonia solanacearum to four fungicides and synergistic toxicity of combinatory fungicides

To screen the effective fungicides inhibiting tobacco bacterial wilt, streptomycin was used as the control agent, and the sensitivities of Ralstonia solanacearum to fungicides fluazinam, SYP-14288, benziothiazolinone and kasugamycin were determined by Bioscreen C growth curve tester. The synergistic interactions between fluazinam and nano sulfur, nano copper, nano silver at nine combination ratios were tested respectively by the Wadley method. The results showed that the average EC₅₀ values of SYP-14288 and fluazinam against R. solanacearum were 0.037 8 and 0.305 0 μg/mL, the distribution ranges of EC₅₀ were 0.018 7-0.053 4 μg/mL and 0.147 1-0.890 4 μg/mL respectively. The average EC₅₀ values of streptomycin, benziothiazolinone and kasugamycin against R. solanacearum were 0.546 3, 2.429 9 and 9.927 3 μg/mL, indicating that fluazinam and SYP-14288 could effectively inhibit the growth of R. solanacearum, and their control effects were better than that of streptomycin. The sensitivity baselines of R. solanacearum to the five fungicides all obeyed normal distribution with continuous single peak curves, which could be used for monitoring the strains resistant to R. solanacearum in tobacco fields. The EC₅₀ of the combined fluazinam and nano fungicides at different ratios were all lower than that of single nano fungicide. The combination of fluazinam and nano sulfur at a volume ratio of 1 ∶ 40 had a synergistic coefficient of 1.60. The additive effect was the most obvious when fluazinam and nano copper were mixed at the ratio of 80 ∶ 1 (EC₅₀=0.142 2 μg/mL). There was an additive effect by mixing fluazinam and nano silver at 1∶20, and the synergistic coefficient was 1.41.