Seidl Johnson Anna C, Jordan Stephen A, Gevens Amanda J
Department of Plant Pathology, University of Wisconsin-Madison, Madison 53706.
Plant Dis. 2015 May;99(5):641-647. doi: 10.1094/PDIS-04-14-0427-RE. Epub 2015 Apr 30.
Late blight, caused by Phytophthora infestans, is one of the most economically important diseases of potato and tomato worldwide. Repeated preventative application of fungicides is the primary means of control on susceptible solanaceous host crops. For organic production, fungicide choices are limited, and little efficacy data on noncopper options is available on which to base control recommendations. Twelve fungicides, including organic and conventional selections, were evaluated for both preventative and postinfection control of a single infection cycle of late blight caused by isolates representing three recently identified P. infestans clonal lineages (US-22, US-23, and US-24) using a detached tomato leaf assay. A subset of the most effective fungicides was also tested for preventative control of a single infection cycle of late blight caused by an isolate of US-23 on potted whole tomato plants under laboratory conditions. Fungicide applications made 2 days after inoculation failed to significantly control late blight on detached leaves in all treatments, with the exception of Bravo Ultrex (US-23 only) and Phostrol (US-22 only). Preventative fungicide applications of Bravo Ultrex, Ridomil Gold SL, Revus, Zonix, and low and high rates of EF400 significantly controlled late blight caused by US-22, -23, and -24 isolates. Additionally, preventative application of Phostrol significantly controlled late blight caused by the US-22 isolate; and Phostrol, low rate of Mycostat, and high rate of Champ significantly controlled late blight caused by the US-23 isolate. Late blight caused by the US-24 isolate was significantly reduced compared with US-22 and US-23 isolates for all fungicide treatments applied after inoculation, as well as for all preventative fungicide treatments, with the exception of Bravo, Ridomil, and Revus. In whole-potted-plant assays with the US-23 isolate, late blight was significantly controlled by preventative application of Bravo Ultrex, Ridomil Gold SL, and high rate of EF400; disease was not significantly controlled by Zonix, low rate of EF400, Phostrol, or low and high rates of Champ. Based on these results, it is anticipated that currently available fungicides with suitability to conventional and organic systems can effectively control late blight caused by new clonal lineages of P. infestans when applied preventatively and that late blight caused by the US-24 clonal lineage may require less fungicide use than US-22 or US-23 to mitigate disease.
晚疫病由致病疫霉引起，是全球马铃薯和番茄最具经济重要性的病害之一。对易感茄科寄主作物反复进行预防性施药是主要的防治手段。对于有机生产而言，杀菌剂的选择有限，且关于非铜制剂选项的药效数据很少，难以据此提出防治建议。使用离体番茄叶片试验，对包括有机和传统制剂在内的12种杀菌剂进行了评估，以防治由代表最近鉴定出的3个致病疫霉克隆谱系（US-22、US-23和US-24）的分离株引起的晚疫病单个侵染循环的预防和感染后控制。还对一部分最有效的杀菌剂进行了测试，以在实验室条件下对盆栽整株番茄上由US-23分离株引起的晚疫病单个侵染循环进行预防控制。接种后2天施药，除Bravo Ultrex（仅针对US-23）和Phostrol（仅针对US-22）外，所有处理对离体叶片上的晚疫病均未能显著控制。Bravo Ultrex、瑞毒霉·锰锌悬浮剂、甲霜灵、Zonix以及低剂量和高剂量的EF400进行预防性施药，可显著控制由US-22、-23和-24分离株引起的晚疫病。此外，Phostrol进行预防性施药可显著控制由US-22分离株引起的晚疫病；Phostrol、低剂量的制霉菌素和高剂量的克菌丹可显著控制由US-23分离株引起的晚疫病。与US-22和US-23分离株相比，对于接种后施用的所有杀菌剂处理以及除Bravo、瑞毒霉和甲霜灵之外的所有预防性杀菌剂处理，由US-24分离株引起的晚疫病均显著减轻。在对US-23分离株进行的盆栽整株试验中，Bravo Ultrex、瑞毒霉·锰锌悬浮剂和高剂量的EF400进行预防性施药可显著控制晚疫病；Zonix、低剂量的EF400、Phostrol或低剂量和高剂量的克菌丹对病害的控制效果不显著。基于这些结果，可以预期，目前适用于传统和有机系统的杀菌剂在进行预防性施药时能够有效控制由致病疫霉新克隆谱系引起的晚疫病，并且与US-22或US-23相比，由US-24克隆谱系引起的晚疫病可能需要较少的杀菌剂使用量来减轻病害。
