山东省和河北省黄瓜霜霉病菌对烯酰吗啉及双炔酰菌胺的抗性监测

为明确黄瓜霜霉病菌对烯酰吗啉及双炔酰菌胺的抗性时空动态及这两种药剂对黄瓜霜霉病的田间防效,采用叶盘漂浮法检测了2011～2016年采自河北省和山东省黄瓜主产区的霜霉病菌1 821个菌株对烯酰吗啉及双炔酰菌胺的敏感性,并采用茎叶喷雾法对这两种药剂的田间防效进行评估。结果表明:黄瓜霜霉病菌1 821个菌株对烯酰吗啉和双炔酰菌胺抗性频率分别为88.5%和34.3%,供试菌株中对烯酰吗啉的低抗菌株及对双炔酰菌胺的敏感菌株占优势,平均抗性倍数分别为8.92和2.44,抗性指数分别为0.42和0.27。黄瓜霜霉病菌对这两种药剂的抗性频率、抗性倍数及抗性指数随着监测年限及地域的不同而波动。在河北定兴和山东寿光日光温室进行的田间药效试验中,按照药剂田间推荐剂量喷施4次,50%烯酰吗啉可湿性粉剂和250 g·L~(-1)双炔酰菌胺悬浮剂对黄瓜霜霉病表现出良好的防效(85%以上),与两地黄瓜霜霉病菌对烯酰吗啉产生低抗、对双炔酰菌胺敏感的监测结果一致。由此推断,50%烯酰吗啉可湿性粉剂和250 g·L~(-1)双炔酰菌胺悬浮剂可在对甲霜灵(或精甲霜灵)、噁霜灵及嘧菌酯普遍产生抗性的地区,作为58%甲霜灵·代森锰锌WP、68%精甲霜灵·代森锰锌WG、64%噁霜灵·代森锰锌WP和250 g·L~(-1)嘧菌酯SC的替代药剂单独使用或与不同作用机理的杀菌剂混用,防治黄瓜霜霉病。

Resistance monitoring of Pseudoperonospora cubensis to dimethomorph and mandipropamid in Hebei and Shandong provinces of China

The study was conducted to clarify the temporal and spatial dynamics of resistance to dimethomorph, mandipropamid in Pseudoperonospora cubensis in Hebei and Shandong provinces of China and control effects of the corresponding fungicides against cucumber downy mildew in the fields. The sensitivities to dimethomorph and mandipropamid in 1 821 P. cubensis strains collected from main cucumber production areas of Hebei province and Shandong province from 2011 to 2016 were measured with the leaf disc floating method, and the control efficacies of the two fungicides against cucumber downy mildew were assayed in the fields with the method of by spraying stems and leaves. The results showed that the strains lowly resistant to dimethomorph, and sensitive to mandipropamid predominate in all 1 821 P. cubensis strains, resistance frequencies to dimethomorph, mandipropamid were 88.5% and 34.3%, respectively; average resistance factors to the two fungicides were 8.92 and 2.44, respectively; and resistance index to the two fungicides were 0.42 and 0.27, respectively. Resistance frequencies, resistance factors and resisance index of P. cubensis to the two fungicides fluctuated over years of monitoring and locations of sampling. In the field trials of control efficacy performed at the solar greenhouses in Dingxing region of Hebei province and Shouguang region of Shandong province with two fungicides sprayed four times under the recommended doses, the good control efficacies of more than 85.00% were given by dimethomorph 50 WP or mandipropamid 250 g·L^-1 SC, the good performance of the two fungicides in controlling cucumber downy mildew was consistent with the resistance monitoring results that P. cubensis developed low resistance to dimethomorph and remained sensitive to mandipropamid in Hebei province and Shandong province. Thus, dimethomorph 50 WP and mandipropamid 250 g·L^-1 SC could be used singly or in mixtures with the other fungicides with different modes of action for control of cucumber downy mildew in the areas where P. cubensis widely developed high resistance to metalaxyl mefenoxam oxadixyl or azoxystrobin as substitutes for metalaxyl·mancozeb 58 WP, mefenoxam·mancozeb 68 WG, oxadixyl·mancozeb 64 WP and azoxystrobin 250 g·L^-1 SC.