马铃薯晚疫病菌对不同药剂敏感性及相应药剂田间防效验证

Sensitivity to Fungicides of Phytophthora infestans and Controlling Efficacy of Corresponding Fungicides against Potato Late Blight

[目的]确定马铃薯晚疫病菌对不同杀菌剂的敏感性并通过田间药效试验加以验证。[方法]采用菌丝生长速率法测定从吉林敦化市和河北围场县采集的马铃薯晚疫病菌对药剂的敏感性,并进行田间药效试验验证。[结果]2地的晚疫病菌对甲霜灵的抗性频率均达100%,菌株均为高抗,抗性水平高达上万倍;对嘧菌酯、霜脲氰、烯酰吗啉抗性频率为0~63.6%,抗性水平为0.33~2.84倍,抗性菌株均为低抗;对氟吡菌胺抗性频率高达84.6%~100%,但抗性菌株均为低抗,抗性水平为3.56~3.90倍;按照推荐剂量4次施药后第7天,58%甲霜·锰锌WP及68%精甲·锰锌WG的防效均显著低于80%代森锰锌WP的防效,而72%霜脲·锰锌WP、50%烯酰吗啉WP、250 g/L嘧菌酯SC和687.5 g/L氟菌·霜霉威SC具有良好防效。[结论]田间抗性发生情况为相应产品的田间药效所验证：马铃薯晚疫病菌对甲霜灵产生严重抗性而导致58%甲霜·锰锌WP及68%精甲·锰锌WG中甲霜灵或精甲霜灵防效丧失及58%甲霜·锰锌WP及68%精甲·锰锌WG防效降低,而晚疫病菌对霜脲氰、烯酰吗啉、嘧菌酯、氟吡菌胺仍保持敏感,72%霜脲·锰锌WP、50%烯酰吗啉WP、250 g/L嘧菌酯SC、687.5 g/L氟菌·霜霉威SC仍可用于马铃薯晚疫病的防治。

[Aims] The paper aims to determine the sensitivity to different fungicides of Phytophthora infestans and validate the efficacies by field trails. [Methods] The sensitivity to different fungicides of P. infestans isolates collected from Dunhua in Jilin province and Weichang Manchu and Mongolian autonomous county in Hebei province in 2014 and 2015 was determined by mycelium growth rate test. The control efficacies of different fungicides against potato late blight were tested in those two areas in 2014-2015. [Results] The frequency of high metalaxyl-resistant isolates of P.infestans in those two areas was up to 100% and the resistance factors of the isolates were more than 10 thousand. The frequencies of resistant isolates to azoxystrobin, cymoxanil and dimethomorph were 0-63.6% and the resistance factors ranged from 0.33 to 2.84, and the isolates were all low resistant. The frequency of resistant isolates to fluopicolide was up to 84.6-100%, but the resistant isolates were low resistant and the resistance factors ranged from 3.56 to 3.90. The7 th day after 4 sprays at the recommended rates, the metalaxyl-mancozeb 58% WP and mefenoxam-mancozeb 68%WP were significantly less effective than mancozeb 80% WP against late blight, cymoxanil-mancozeb 72% WP,dimethomorph 50% WP, azoxystrobin 250 g/L SC, fluopicolide-propamocab hydrochloride 687.5 g/L SC remained good control efficacies against late blight. [Conclusions] Severe resistance occurrence in P. infestans to metalaxyl led to the loss of efficacy of metalaxyl or mefenoxam in metalaxyl-mancozeb 58% WP and mefenoxam-mancozeb 68% WP and decrease of efficacy of the two mixture formulations in the two areas, but no severe resistance occurred to dimethomorph, azoxystrobin, fluopicolide and cymoxanil, therefore, cymoxanil-mancozeb 72% WP, dimethomorph50% WP, azoxystrobin 250 g/L SC, fluopicolide-propamocab hydrochloride 687.5 g/L SC can be used for control of potato late blight instead of fungicides containing metalaxyl or mefenoxam.