Phytopathology. 2007 Sep;97(9):1186-94. doi: 10.1094/PHYTO-97-9-1186.
Sclerotinia stem rot (SSR) is an increasing threat to winter oilseed rape (OSR) in Germany and other European countries due to the growing area of OSR cultivation. A forecasting model was developed to provide decision support for the fungicide spray against SSR at flowering. Four weather variables-air temperature, relative humidity, rainfall, and sunshine duration-were used to calculate the microclimate in the plant canopy. From data reinvestigated in a climate chamber study, 7 to 11 degrees C and 80 to 86% relative humidity (RH) were established as minimum conditions for stem infection with ascospores and expressed as an index to discriminate infection hours (Inh). Disease incidence (DI) significantly correlated with Inh occurring post-growth stage (GS) 58 (late bud stage) (r(2) = 0.42, P </= 0.001). Using the sum of Inh from continuous infection periods exceeding 23 h significantly improved correlation with DI (r(2) = 0.82; P </= 0.001). A parallel GS model calculates the developmental stages of OSR based on temperature in the canopy and starts the model calculation at GS 58. The novel forecasting system, SkleroPro, consists of a two-tiered approach, the first providing a regional assessment of the disease risk, which is assumed when 23 Inh have accumulated after the crop has passed GS 58. The second tier provides a field-site-specific, economy-based recommendation. Based on costs of spray, expected yield, and price of rapeseed, the number of Inh corresponding to DI at the economic damage threshold (Inh(i)) is calculated. A decision to spray is proposed when Inh >/= Inh(i). Historical field data (1994 to 2004) were used to assess the impact of agronomic factors on SSR incidence. A 2-year crop rotation enhanced disease risk and, therefore, lowered the infection threshold in the model by a factor of 0.8, whereas in 4-year rotations, the threshold was elevated by a factor 1.3. Number of plants per square meter, nitrogen fertilization, and soil management did not have significant effects on DI. In an evaluation of SkleroPro with 76 historical (1994 to 2004) and 32 actual field experiments conducted in 2005, the percentage of economically correct decisions was 70 and 81%, respectively. Compared with the common practice of routine sprays, this corresponded to savings in fungicides of 39 and 81% and to increases in net return for the grower of 23 and 45 euro/ha, respectively. This study demonstrates that, particularly in areas with abundant inoculum, the level of SSR in OSR can be predicted from conditions of stem infection during late bud or flowering with sufficient accuracy, and does not require simulation of apothecial development and ascospore dispersal. SkleroPro is the first crop-loss-related forecasting model for a Sclerotinia disease, with the potential of being widely used in agricultural practice, accessible through the Internet. Its concept, components, and implementation may be useful in developing forecasting systems for Sclerotinia diseases in other crops or climates.
菌核病茎腐（SSR）由于冬油菜（OSR）种植面积的增加，对德国和其他欧洲国家的冬油菜构成了日益严重的威胁。本文开发了一个预测模型，为开花期 SSR 杀菌剂喷雾提供决策支持。使用四个气象变量——空气温度、相对湿度、降雨量和日照时间——来计算植物冠层中的小气候。从在气候室研究中重新调查的数据中，确定了 7 到 11°C 和 80 到 86%的相对湿度（RH）是菌核感染子囊孢子的最低条件，并表示为区分感染时间（Inh）的指数。病害发生率（DI）与生长阶段（GS）58 后（晚芽期）的 Inh 显著相关（r²=0.42，P≤0.001）。使用连续感染时间超过 23 小时的 Inh 总和显著提高了与 DI 的相关性（r²=0.82；P≤0.001）。一个平行的 GS 模型根据冠层中的温度计算 OSR 的发育阶段，并在 GS 58 后开始模型计算。新型预测系统 SkleroPro 由两层组成，第一层提供疾病风险的区域评估，当作物通过 GS 58 后累计 23 个 Inh 时，就会进行假设。第二层提供基于特定地点和经济的建议。基于喷雾成本、预期产量和油菜籽价格，计算出与经济损害阈值（Inh(i)）对应的 DI 的 Inh 数量。当 Inh≥Inh(i)时，就会提出喷雾的建议。使用 1994 年至 2004 年的历史田间数据评估了农业因素对 SSR 发病率的影响。两年的轮作增加了疾病风险，因此在模型中降低了感染阈值 0.8 倍，而在四年轮作中，阈值提高了 1.3 倍。每平方米的植物数量、氮施肥和土壤管理对 DI 没有显著影响。在对 SkleroPro 的评估中，使用了 76 个历史（1994 年至 2004 年）和 2005 年进行的 32 个实际田间试验，经济上正确决策的百分比分别为 70%和 81%。与常规喷雾的常规做法相比，这分别对应于杀菌剂节省 39%和 81%，以及种植者净收益增加 23%和 45 欧元/公顷。这项研究表明，特别是在菌核丰富的地区，可以从晚芽期或开花期的茎部感染条件中准确预测 OSR 中的 SSR 水平，而无需模拟子囊盘发育和子囊孢子传播。SkleroPro 是第一个与作物损失相关的菌核病预测模型，具有在农业实践中广泛应用的潜力，可通过互联网访问。它的概念、组成部分和实施可能对开发其他作物或气候下菌核病预测系统有用。
