四种替代药剂对梨火疫病菌的抑制活性及其田间防效

Antibacterial activity of four alternative bactericides and their field control efficacies against pear fire blight pathogen

为筛选农用链霉素替代药剂,以其为对照药剂,测定春雷霉素、中生菌素、噻霉酮和噻菌铜这4种常用细菌病害防治药剂对梨火疫病菌Erwinia amylovora的抑制活性、对梨火疫病的田间防效及不同药剂处理后梨中的农药残留,并对这4种药剂的作物安全性进行评价。结果表明,中生菌素、噻霉酮和春雷霉素对梨火疫病菌有抑制作用,抑制中浓度EC_(50)分别为1.60、6.64和60.57 mg/L,中生菌素的抑制效果高于链霉素。在连续2年田间试验中,中生菌素1000倍液和春雷霉素400倍液对梨火疫病的保护效果和治疗效果均达90.33%以上,噻霉酮500倍液和噻菌铜200倍液对梨火疫病的保护效果均达100.00%,治疗效果均超过86.97%,与对照药剂农用链霉素2000倍液的效果相当。所有药剂处理后均未检出中生菌素、春雷霉素、高效氯氰菊酯和农用链霉素的农药残留,而噻虫嗪、阿维菌素和矮壮素虽有检出,但其残留量均低于国家限量标准。花期前后、幼果期和果实膨大期施药,中生菌素、春雷霉素、噻霉酮和噻菌铜对梨花、叶片、枝梢及果实生长均无不良影响。综合来看,中生菌素、春雷霉素、噻霉酮和噻菌铜均可作为农用链霉素的替代药剂,用于防治梨火疫病。

To screen alternative bactericides for streptomycin,four commonly used bactericides kasugamycin,mesosporin,benziothiazolinone and thiodiazole-copper were tested for their inhibitory effect against fire blight pathogen Erwinia amylovora in vitro,and their preventive and therapeutic effects to control pear fire blight in the field trials.The growth rate method and conventional spray method were used to determine the bacteriostatic activity,control efficacy,and pesticide residue of four bactericides,and their possible damage to crops were evaluated in field trials.The results showed that mesosporin,kasugamycin and benziothiazolinone all showed inhibitory effects on E.amylovora.The EC_(50) values of mesosporin,kasugamycin and benziothiazolinone were 1.60,6.64 and 60.57 mg/L,respectively,and the first two have more obvious antibacterial effects than streptomycin.In two consecutive years of field trials,the preventive and therapeutic effects of mesosporin with 1000 fold and kasugamycin with 400 fold dilution were more than 90.33%.Both the preventive effects of benziothiazolinone with 500 fold dilution and thiodiazole-copper with 200 fold dilution reached 100.00%,and the therapeutic effects of the two bactericides on pear fire blight were over 86.97%,which was close to that of streptomycin with 2000 fold dilution treatment.The residues of mesosporin and kasugamycin in the tested pear fruits were not detected before harvest.Although thiamethoxam,avermectin,and cycocel were detected,their residual levels were all below the Chinese national limit standards.At the present study,the tested bactericides were applied at the beginning and ending of florescence,the young fruit and the fruit expansion stages.The results showed that the application of mesosporin,kasugamycin,benziothiazolinone and thiodiazole-copper within the concentration range of the experimental design at the tested growing stage,no adverse effects on the growth of pear flowers,leaves,branches and fruits were observed.To conclude,mesosporin,kasugamycin,benziothiazolinone and thiodiazole-copper can be used as alternative bactericides for streptomycin to control pear fire blight.