河北省甘薯根腐病菌种类鉴定及高效化学药剂筛选OA

To clarify the pathogenic species causing sweet potato root rot in Hebei province and to screen highly ef-fective control agents,typical diseased sweet potato samples were collected from five cities:Shijiazhuang,Baoding,Hengshui,Langfang,and Qinhuangdao.After isolation and purification of pathogens,identification was carried out by combining morphological characterization,phylogenetic analysis based on ITS-TEF-1α multigene sequences,and pathogenicity tests.Toxic effects of eight commonly used fungicides against the dominant pathogen were determined us-ing the mycelial growth rate method,aiming to select highly effective and low-toxic chemical agents.Field efficacy tri-als were further conducted in fields with five years of continuous sweet potato cropping.The results showed that a to-tal of 123 strains of Fusarium were isolated and purified,identified as five species:Fusarium oxysporum,F.prolifera-tum,F.denticulatum,F.solani,and F.subglutinans.Among these,F.oxysporum was the dominant pathogen,with an isolation frequency of 54.47%.In vitro toxicity assays indicated that triazole fungicides exhibited significant inhibitory activity,with 250 g/L propiconazole EC showing the strongest inhibition against Fusarium oxysporum(EC50=0.0859 μg/mL).In field trials,three drip irrigations of propiconazole provided a control efficacy of 63.36%and increased yield by 18.45%.A single application of 450 g/L fluopyram achieved a control efficacy of 52.67%and increased yield by 11.52%,demonstrating potential for"reduced application with maintained efficacy".This study confirms F.oxysporum as the dominant pathogen causing sweet potato root rot in Hebei province,and suggests that propiconazole and fluopy-ram can serve as preferred chemical options for field control of this disease.