Carisse O, Lefebvre A, Van der Heyden H, Roberge Linda, Brodeur Luc
Agriculture and Agri-Food Canada, St.-Jean-sur-Richelieu, QC J3B 3E6, Canada.
Compagnie de recherche Phytodata Inc., Sherrington, QC J01 2N0, Canada.
Plant Dis. 2013 Mar;97(3):354-362. doi: 10.1094/PDIS-05-12-0508-RE.
The relationships between strawberry powdery mildew incidence (I) and severity (S) were investigated for various cultivars, for June-bearing and day-neutral cultivars, and for production systems (open-field and plastic-tunnel) with the objective of deriving a simple relationship for predicting severity (proportion of leaf area diseased [PLAD]) from incidence (proportion of diseased leaves). Data were collected from 2006 to 2011 at 11 commercial and experimental sites, for a total of 2,326 observations (n). For the cultivars grown in open fields, higher severity was observed on 'Seascape', with mean PLAD of 0.299 (n = 427); followed by 'Chambly', with 0.133 (n = 334); 'Cavendish', with 0.115 (n = 250); 'Darselect', with 0.111 (n = 321); and 'Jewel', with 0.105 (n = 276). In general, mean severity was higher when the strawberry plants were grown in plastic tunnels, with PLAD of 0.204, 0.199, and 0.181 for Chambly (n = 204), Darselect (n = 261), and Jewel (n = 253), respectively. A linear model based on complementary log-log transformation of I and S provided a good fit of the data (coefficient of determination [R] adjusted for degrees of freedom from 0.82 to 0.96). A covariance analysis indicated that the sampling year and site of sampling did not significantly influence the estimated slope of the I-S relationship, nor did the specific cultivar among the June-bearing ones, whereas the production system (open-field versus plastic-tunnel) and the cultivar type (June-bearing versus day-neutral) significantly influenced the estimated slope. From this analysis, we were able to develop three specific models for open-field-grown June-bearing cultivars (R = 0.90), for the open-field-grown day-neutral cultivar (Seascape, R= 0.91), and for June-bearing cultivars grown in plastic tunnels (R = 0.92). From these results, it was concluded that strawberry powdery mildew leaf severity can be accurately estimated from incidence of diseased leaves. The I-S relationships developed in the present study may be used in making practical disease management decisions, especially for management programs that use information on disease level in the field to initiate fungicide spraying programs or to time the interval between sprays.
针对不同品种、四季结果型和日中性品种以及不同生产系统（露地和塑料大棚），研究了草莓白粉病发病率（I）与病情严重程度（S）之间的关系，目的是推导出一个简单的关系，以便根据发病率（病叶比例）预测病情严重程度（病叶面积比例[PLAD]）。2006年至2011年期间，在11个商业和试验地点收集了数据，共计2326个观测值（n）。对于露地种植的品种，“海景”的病情严重程度较高，平均PLAD为0.299（n = 427）；其次是“尚布利”，为0.133（n = 334）；“卡文迪什”，为0.115（n = 250）；“达塞尔”，为0.111（n = 321）；“宝石”，为0.105（n = 276）。一般来说，草莓植株在塑料大棚中种植时平均病情严重程度更高，“尚布利”（n = 204）、“达塞尔”（n = 261）和“宝石”（n = 253）的PLAD分别为0.204、0.199和0.181。基于I和S的互补对数-对数变换的线性模型对数据拟合良好（调整后的决定系数[R]从0.82到0.96）。协方差分析表明，采样年份和采样地点对I-S关系的估计斜率没有显著影响，四季结果型品种中的特定品种也没有影响，而生产系统（露地与塑料大棚）和品种类型（四季结果型与日中性）对估计斜率有显著影响。通过该分析，我们能够为露地种植的四季结果型品种（R = 0.90）、露地种植的日中性品种（“海景”，R = 0.91）以及塑料大棚中种植的四季结果型品种（R = 0.92）开发三个特定模型。从这些结果可以得出结论，草莓白粉病的叶部病情严重程度可以根据病叶发病率准确估计。本研究中建立的I-S关系可用于做出实际的病害管理决策，特别是对于那些利用田间病害水平信息启动杀菌剂喷洒计划或确定喷洒间隔时间的管理方案。
