唐菖蒲伯克霍尔德菌H02与噻呋酰胺联用对花生白绢病的防控效果

Control effect of Burkholderia gladioli H02 combined with thifluzamide on peanut southern blight

摘要:

目的 由齐整小核菌(Sclerotium rolfsii Sacc.)侵染引起的白绢病是制约花生生产的重要土传病害。当前防控主要依赖化学药剂，为提高田间防效、降低农药用量、减少花生农药残留，本研究筛选了齐整小核菌的拮抗微生物，并探索了其与化学药剂协同防控花生白绢病的效果，以期为该病害的绿色防控提供技术支持。方法 通过平板筛选实验获得对齐整小核菌拮抗活性强且与常用真菌杀菌剂相容性好的生防菌株；经药剂筛选实验获得对齐整小核菌抑制效果显著且不影响生防菌株生长的防控药剂；通过室内联合毒力测定实验，在含有不同浓度噻呋酰胺(0.15 μg/mL、0.30 μg/mL)、10% H02无菌发酵液或其复合物的PDA平板上接种病原菌，观察菌丝生长并计算抑制率与抑制比率(inhibition ratio, IR)，评价二者联用的相互作用类型。通过盆栽试验，比较菌液、全剂量药剂(田间推荐用量)及菌液与半剂量药剂联用对花生白绢病的防治效果。结果 筛选获得一株拮抗活性高、与杀菌剂相容性良好的唐菖蒲伯克霍尔德菌(Burkholderia gladioli) H02，其平板抑制率为76.03%。同时，筛选获得对齐整小核菌抑制效果显著(EC₅₀为0.151 3 μg/mL)且不影响H02生长的药剂噻呋酰胺。室内联合毒力测定结果表明，H02无菌发酵液与噻呋酰胺复配处理组的IR均大于1，表现为协同作用类型；且减半浓度噻呋酰胺与发酵液联用对菌丝和菌核的抑制率(分别为74.91%和95.58%)显著高于全浓度噻呋酰胺单剂处理(分别为68.04%和83.67%)。盆栽结果显示，H02菌液与半剂量噻呋酰胺联用的防效(68.94%)与全剂量噻呋酰胺(66.63%)防效相当，分别为68.94%与66.63%，单施H02菌液的防效为61.17%。结论 唐菖蒲伯克霍尔德菌H02与噻呋酰胺联用可发挥协同防治作用，在维持防治效果的同时减少化学药剂用量，展现出良好的应用潜力。

Abstract:

Objective Southern blight, caused by Sclerotium rolfsii Sacc., is a major soil-borne disease that limits peanut production. At present, its management relies mainly on chemical fungicides. To improve the field control efficacy, reduce fungicide application rates, and lower pesticide residues in peanuts, this study screened antagonistic microorganisms against S. rolfsii and evaluated their synergistic effects with chemical fungicides in the control of peanut southern blight. The results are expected to provide technical support for the green and sustainable management of this disease.Methods This study first used a plate-based screening assay to obtain biocontrol strains showing strong antagonistic activity against S. rolfsii and high compatibility with commonly used fungicides. Next, a fungicide screening assay was conducted to identify control agents that effectively inhibited S. rolfsii without adversely affecting the growth of the biocontrol strains. Subsequently, an in vitro combined toxicity assay was performed. The pathogen was inoculated onto PDA plates containing different concentrations of thifluzamide (0.15 and 0.30 μg/mL), sterile 10% fermentation broth of H02, or their mixtures. Fungal growth was observed, and the inhibition rate and inhibition ratio (IR) were calculated to evaluate the interaction type of the combined treatment. Finally, a pot experiment was carried out to compare the control efficacy against peanut southern blight among the fermentation broth, the full-dose fungicide (recommended field rate), and the combination of fermentation broth with a half-dose fungicide.Results A Burkholderia gladioli strain H02 with high antagonistic activity and good fungicide compatibility was screened out, exhibiting an inhibition rate of 76.03%. Concurrently, thifluzamide was identified as a fungicide with strong inhibitory activity against S. rolfsii and no negative impact on the growth of strain H02, exhibiting an EC₅₀ of 0.151 3 μg/mL. Results from the in vitro combined toxicity assay indicated that the combination of the H02 fermentation broth and thifluzamide showed an IR greater than 1, exhibiting a synergistic effect. Moreover, the combination of half the concentration of thifluzamide with the fermentation broth significantly demonstrated higher inhibition rates against pathogen mycelia and sclerotia (74.91% and 95.58%, respectively) than the full concentration of thifluzamide alone (68.04% and 83.67%, respectively). Pot experiment results showed that the combination of H02 fermentation broth and half dosage of thifluzamide had the control efficacy comparable to that of the full dosage of thifluzamide (68.94% vs. 66.63%), whereas the single application of H02 fermentation broth provided the control efficacy of 61.17%.Conclusion The combined application of B. gladioli H02 and thifluzamide can achieve synergistic control of peanut southern blight and reduce chemical fungicide usage while maintaining effective disease control, thus showing promising potential for practical application.