Mueller T A, Miles M R, Morel W, Marois J J, Wright D L, Kemerait R C, Levy C, Hartman G L
Department of Crop Sciences, University of Illinois, Urbana, IL 61801.
USDA-ARS, National Soybean Research Center, Urbana, IL 61801.
Plant Dis. 2009 Mar;93(3):243-248. doi: 10.1094/PDIS-93-3-0243.
Soybean rust, caused by Phakopsora pachyrhizi, is a devastating foliar disease of soybean that may cause significant yield losses if not managed by well-timed fungicide applications. To determine the effect of fungicide timing on soybean rust severity and soybean yield, field trials were completed in Paraguay (four locations), the United States (two locations), and Zimbabwe (one location) from 2005 to 2006. Treatments at each location included applications of tebuconazole, pyraclostrobin, or a combination of azoxystrobin + propiconazole, and in some locations pyraclostrobin + tebuconazole at the following soybean growth stages (GS): (i) GS R1 (beginning flowering), (ii) GS R3 (beginning pod), (iii) GS R5 (beginning seed), (iv) GS R1 + R3, (v) GS R3 + R5, and (vi) GS R1 + R3 + R5. Soybean yields from plots treated with fungicides were 16 to 114% greater than yields from no fungicide control plots in four locations in Paraguay, 12 to 55% greater in two locations in the United States, and 31% greater in Zimbabwe. In all locations, rust severity measured over time as area under the disease progress curve (AUDPC) was negatively correlated (r = -0.3, P < 0.0001) to yield. The effectiveness of any given treatment (timing of application and product applied) was often dependent on when rust was first detected and the intensity of its development. For example, when soybean rust was first observed before GS R3 (two locations in Paraguay), the plants in plots treated with a fungicide at GS R1 had the lowest AUPDC values and highest yields. When soybean rust was first observed after GS R3, plants treated with a fungicide at GS R3 and/or GS R5 had the lowest AUDPC values and highest yields with a few exceptions.
由大豆锈菌（Phakopsora pachyrhizi）引起的大豆锈病是一种极具破坏性的大豆叶部病害，如果不及时施用杀菌剂进行防治，可能会导致严重的产量损失。为了确定杀菌剂施用时间对大豆锈病严重程度和大豆产量的影响，2005年至2006年在巴拉圭（4个地点）、美国（2个地点）和津巴布韦（1个地点）开展了田间试验。每个地点的处理包括在以下大豆生长阶段（GS）施用戊唑醇、吡唑醚菌酯或嘧菌酯+丙环唑的组合，在一些地点还施用了吡唑醚菌酯+戊唑醇：（i）GS R1（始花），（ii）GS R3（始荚），（iii）GS R5（始粒），（iv）GS R1 + R3，（v）GS R3 + R5，以及（vi）GS R1 + R3 + R5。在巴拉圭的4个地点，施用杀菌剂处理的小区大豆产量比未施用杀菌剂的对照小区高16%至114%；在美国的2个地点，高12%至55%；在津巴布韦，高31%。在所有地点，随时间测量的以病情进展曲线下面积（AUDPC）表示的锈病严重程度与产量呈负相关（r = -0.3，P < 0.0001）。任何给定处理（施用时间和施用产品）的效果通常取决于首次发现锈病的时间及其发展强度。例如，当在GS R3之前首次观察到大豆锈病时（巴拉圭的2个地点），在GS R1施用杀菌剂处理的小区植株AUPDC值最低且产量最高。当在GS R3之后首次观察到大豆锈病时，在GS R3和/或GS R5施用杀菌剂处理的植株AUDPC值最低且产量最高，但有少数例外情况。
