ESALQ, University of Sao Paulo, Brazil.
Iowa State University, Ames, IA, U.S.A.
Plant Dis. 2020 Apr;104(4):1013-1018. doi: 10.1094/PDIS-01-19-0207-SR. Epub 2020 Feb 17.
The El Niño Southern Oscillation (ENSO) is an oceanic-atmospheric phenomenon influencing worldwide weather and climate. Its occurrence is determined by the sea surface temperature (SST) anomaly of the 3.4 Niño region in the Pacific Ocean (5°N-5°S, 120°-170°W). El Niño (EN), Neutral (NT), and La Niña (LN) are the three possible phases of ENSO, respectively, for warm, normal, and cold SST anomaly. As in other regions around the world, weather in Brazil is influenced by ENSO phases. The country is the major coffee producer in the world, and production is strongly influenced by weather conditions, which affect plant yield, harvest quality, and interactions with pests and diseases. Coffee leaf rust (CLR), caused by the fungus , is a major cause of coffee yield and quality losses in Brazil, and requires fungicide spray applications every season. Because CLR is highly influenced by weather conditions, it is possible to use weather variables to simulate its progress during the cropping cycle. Therefore, the aims of this study were to estimate CLR infection rate based on a validated empirical model, which has daily minimum air temperature and relative humidity as inputs, and to assess the extent of ENSO influence on the annual risk of this disease at 45 sites in Brazil. Cumulative infection rates (CIR) were estimated daily from October to June of each growing season and location, based on the prevailing ENSO phase. Differences between the extreme phases (EN-LN) were assessed by the Two-One-Sided-Tests (TOST) method. Analysis of data from eight sites, located mainly in Paraná State, provided evidence of CIR differences between EN and LN phases (G1). Evidence of no difference of CIR between EN and LN was found in 18 sites (G2), whereas 19 sites showed no evidence of differences (G3) due to relatively large variation of CIR within the same ENSO phase. The G1 sites are located mostly in Southern Brazil, where ENSO exerts a well-defined influence on rainfall regime. In contrast, the G2 sites are mainly in Minas Gerais State, which is characterized as a transition region for ENSO influence on rainfall. The G3 sites are located between the northern region of Minas Gerais State and southern region of Bahia State, which is characterized by a subhumid climate that is usually very dry during winter, and where rainfall can vary up to 300% from one year to another, influencing relative humidity and resulting in a high CIR variability. Therefore, ENSO had a well-defined influence on CIR only in Paraná State, a region with minor importance for coffee production in Brazil. No ENSO influence was found in more northerly zones where the majority of Brazilian coffee is produced. This is the first evidence of ENSO-linked regional impact on the risk of coffee rust.
厄尔尼诺南方涛动（ENSO）是一种影响全球天气和气候的海洋大气现象。其发生由太平洋 3.4 尼诺区域的海面温度（SST）异常决定（5°N-5°S，120°-170°W）。厄尔尼诺（EN）、中性（NT）和拉尼娜（LN）分别是 ENSO 的三个可能阶段，代表暖、正常和冷 SST 异常。与世界其他地区一样，巴西的天气受 ENSO 阶段的影响。该国是世界上最大的咖啡生产国，生产受到天气条件的强烈影响，这些条件影响植物产量、收获质量以及与病虫害的相互作用。咖啡叶锈病（CLR）由真菌引起，是巴西咖啡产量和质量损失的主要原因，每个季节都需要喷洒杀菌剂。由于 CLR 受天气条件的高度影响，因此可以使用天气变量来模拟其在作物周期中的进展。因此，本研究的目的是基于验证的经验模型估计 CLR 感染率，该模型的输入为每日最低空气温度和相对湿度，并评估 ENSO 对巴西 45 个地点该病年度风险的影响程度。根据流行的 ENSO 阶段，在每个生长季节和地点的 10 月至 6 月期间，基于每日最低空气温度和相对湿度，估算累积感染率（CIR）。通过双单边检验（TOST）方法评估 EN 和 LN 极端阶段之间的差异。对主要位于巴拉那州的 8 个地点的数据进行分析，结果表明，EN 和 LN 阶段的 CIR 存在差异（G1）。在 18 个地点（G2）发现 CIR 在 EN 和 LN 之间没有差异的证据，而 19 个地点（G3）由于同一 ENSO 阶段内 CIR 的变化较大，没有差异的证据。G1 地点主要位于巴西南部，那里 ENSO 对降雨模式有明确的影响。相比之下，G2 地点主要位于米纳斯吉拉斯州，那里 ENSO 对降雨的影响是过渡区。G3 地点位于米纳斯吉拉斯州北部和巴伊亚州南部之间，那里气候为亚热带湿润气候，冬季通常非常干燥，年降雨量可相差 300%，这影响了相对湿度，并导致 CIR 高度变化。因此，ENSO 仅在巴拉那州对 CIR 有明确的影响，而巴拉那州对巴西咖啡生产的重要性较小。在巴西大部分咖啡生产的更北地区没有发现 ENSO 影响。这是首次发现 ENSO 与咖啡锈病风险的区域性关联。
