University of Arkansas System Division of Agriculture, Department of Entomology and Plant Pathology, Lonoke Extension Center, Lonoke, AR 72086.
Plant Dis. 2021 Apr;105(4):1108-1114. doi: 10.1094/PDIS-06-20-1247-RE. Epub 2021 Mar 22.
The efficacy and timing of eight foliar fungicides to manage southern rust of corn (caused by Underwood) was investigated over 4 years in three field experiments. Each experiment consisted of one-, two-, or three-fungicide application timings at tassel, milk, or dent growth stages with quinone outside inhibitor (QoI), demethylation inhibitor (DMI), or QoI + DMI fungicides. Each year trace amounts of southern rust were observed in the field at tassel, except in 2018, when rust was not observed until physiological maturity. Southern rust severity on ear leaf and two leaves above the ear leaf was approximately 50, 35, 75, and 0% at dent in 2015, 2016, 2017, and 2018, respectively. Applications that contained a QoI or QoI + DMI fungicide provided greater southern rust control than DMI fungicides, with little variation within fungicide classes. Applications of QoI or QoI + DMI fungicides applied at tassel provided greater disease control (52.5%) than those applied at milk (5.8%) or dent (1.4%), and greater yield protection (40.4%) than those applied at milk (23.7%) or dent (2.6%) when final rust development was severe (>40%). When rust development increased later in the season, after milk growth stage, a trend of better disease control was observed with fungicides applied at milk (57.8%) compared with tassel (35.2%), but grain yield protection was similar, with an average yield protection of 7.4%. There was no yield benefit with fungicides applied in the absence of disease or at the dent growth stage. Southern rust was most effectively managed with QoI or QoI + DMI fungicides applied at tassel when southern rust was present and environmental conditions favored rust development.
在三年的田间试验中，研究了 8 种叶面杀菌剂对玉米南方锈病（由 Underwood 引起）的防治效果和时间。每个试验都包括在穗期、乳熟期或乳熟后期使用一种、两种或三种杀菌剂，杀菌剂分别为醌外抑制剂（QoI）、脱甲基抑制剂（DMI）或 QoI+DMI。除 2018 年外，每年在穗期田间观察到少量南方锈病，但直到生理成熟时才观察到锈病。2015 年、2016 年、2017 年和 2018 年，在乳熟期，耳叶和耳叶上两叶的南方锈病严重度分别约为 50%、35%、75%和 0%。含有 QoI 或 QoI+DMI 杀菌剂的施药处理比 DMI 杀菌剂提供了更好的南方锈病防治效果，而杀菌剂种类之间的差异很小。在穗期施用 QoI 或 QoI+DMI 杀菌剂比在乳熟期（5.8%）或乳熟后期（1.4%）施用的防治效果更好，在终期锈病严重（>40%）时，对产量的保护作用也更大（40.4%），而在乳熟期（23.7%）或乳熟后期（2.6%）施用的保护作用更小。当锈病在季节后期，即乳熟后期之后发展时，与在穗期（35.2%）相比，在乳熟期施用杀菌剂的防治效果更好（57.8%），但籽粒产量保护相似，平均产量保护为 7.4%。在没有病害或在乳熟后期施用杀菌剂时，没有产量收益。在南方锈病存在且环境条件有利于锈病发展的情况下，最好在穗期施用 QoI 或 QoI+DMI 杀菌剂来防治南方锈病。
