Soybean rust (SBR), caused by the fungus Phakopsora pachyrhizi, is the most damaging disease of soybean in Brazil. Effective management is achieved by means of calendar-timed sprays of fungicide mixtures, which do not explicitly consider weather-associated disease risk. Two rain-based action thresholds of disease severity values (DSV50 and DSV80) were proposed and compared with two leaf wetness duration-temperature thresholds of daily values of infection probability (DVIP6 and DVIP9) and with a calendar program, with regard to performance and profitability. An unsprayed check treatment plot was included for calculating relative control. Disease severity and yield data were obtained from 29 experiments conducted at six sites across four states in Brazil during the 2012–13, 2014–15, and 2015–16 growing seasons, which represented different growing regions and climatic conditions. The less conservative rainfall action threshold (DSV80) resulted in fewer fungicide sprays compared with the other treatments, and the more conservative one (DSV50) resulted in fewer sprays than the DVIP thresholds. Yield was generally higher with the increase in spray number, but the economic analysis showed no significant differences in the risk of not offsetting the costs of fungicide sprays regardless of the system. Therefore, based on the simplicity and the profitability of the rain-based model, the system is a good candidate for incorporating into the management of SBR in soybean production fields in Brazil.

大豆锈菌Phakopsora pachyrhizi引起的大豆锈病（SBR），是巴西大豆中最具破坏性的疾病。通过日历定时喷洒的杀菌剂混合物可实现有效管理，这种喷雾剂并未明确考虑与天气相关的疾病风险。提出了两个基于雨水的疾病严重度阈值（DSV50和DSV80），并将其与两个叶片湿度持续时间-温度阈值相结合的日感染概率每日值（DVIP6和DVIP9）以及日历程序，以评估性能和获利能力。包括未喷涂的检查处理图，用于计算相对对照。疾病严重程度和产量数据来自2012-13、2014-15和2015-16生长季节在巴西四个州的六个地点进行的29个实验，这些实验代表不同的生长地区和气候条件。与其他处理相比，保守性较低的降雨作用阈值（DSV80）导致的杀菌剂喷雾减少，而保守性较差（DSV50）导致的喷雾剂数量小于DVIP阈值。随着喷雾数量的增加，产量通常更高，但是经济分析表明，无论采用哪种系统，在不抵消杀真菌剂喷雾成本的风险上都没有显着差异。因此，基于基于雨水的模型的简单性和获利能力，该系统是将其纳入巴西大豆生产领域SBR管理的良好选择。随着喷雾数量的增加，产量通常更高，但是经济分析表明，无论采用哪种系统，在不抵消杀真菌剂喷雾成本的风险上都没有显着差异。因此，基于基于雨水的模型的简单性和获利能力，该系统是将其纳入巴西大豆生产领域SBR管理的良好选择。随着喷雾数量的增加，产量通常更高，但是经济分析表明，无论采用哪种系统，在不抵消杀真菌剂喷雾成本的风险上都没有显着差异。因此，基于基于雨水的模型的简单性和获利能力，该系统是将其纳入巴西大豆生产领域SBR管理的良好选择。