Department of Plant Pathology, The University of Georgia, Tifton, 31793-5766.
Department of Crop and Soil Sciences, The University of Georgia, Tifton, 31793-5766.
Plant Dis. 2017 Nov;101(11):1843-1850. doi: 10.1094/PDIS-02-17-0165-RE. Epub 2017 Jul 19.
Peanut (Arachis hypogaea) cultivars with resistance or tolerance to Cercospora arachidicola and/or Cercosporidium personatum, the causes of early and late leaf spot, respectively, are needed for organic production in the southeastern U.S. To determine the potential of new breeding lines for use in such production systems, field experiments were conducted in Tifton, GA, in 2014 and 2015 in which nine breeding lines and two cultivars, Georgia-06G and Georgia-12Y, were grown without foliar fungicide applications. In one set of trials, cultivar Georgia-12Y and most of the breeding lines evaluated had early season vigor ratings, early-season canopy width measurements, final plant populations, and pod yield that were greater than those of standard cultivar Georgia-06G. In those trials, final late leaf spot Florida scale ratings were lower and canopy reflectance measured as the normalized difference vegetation index (NDVI), was higher all the breeding lines than those of Georgia-06G. In another set of trials, two of those same breeding lines had final late leaf spot ratings similar to those of Georgia-12Y in 2014, whereas in 2015, six of those breeding lines had final leaf spot ratings that were lower than those of Georgia-12Y. Yields were similar for Georgia-12Y and all the breeding lines in the Gibbs Farm trials. Across years and breeding lines at the Lang Farm, the relationship between visual estimates of defoliation and NDVI was described by a two sector piecewise regression with NDVI decreasing more rapidly with increasing defoliation above approximately 89%. The utility of NDVI for spot comparisons among breeding lines appears to be limited to situations where there are differences in defoliation. Georgia-12Y and multiple breeding lines evaluated show potential for use in situations such as organic production where acceptable fungicides available for seed treatment and leaf spot control are limited.
需要具有对分别导致早、晚期叶斑病的 Cercospora arachidicola 和/或 Cercosporidium personatum 具有抗性或耐受性的落花生（Arachis hypogaea）品种，用于美国东南部的有机生产。为了确定新的育成系在这种生产系统中的应用潜力，于 2014 年和 2015 年在佐治亚州的蒂夫顿进行了田间试验，其中 9 个育成系和两个品种，即佐治亚州 06G 和佐治亚州 12Y，在没有叶面杀菌剂应用的情况下进行种植。在一组试验中，与标准品种佐治亚州 06G 相比，品种佐治亚州 12Y 和评估的大多数育成系的早期季节活力评分、早期季节冠层宽度测量、最终植物种群和荚果产量更高。在这些试验中，最终的晚期叶斑病佛罗里达州量表评分较低，归一化差异植被指数（NDVI）测量的冠层反射率高于佐治亚州 06G 的所有育成系。在另一组试验中，2014 年，在这两个相同的育成系中，有两个具有与佐治亚州 12Y 相似的晚期叶斑病评分，而在 2015 年，有六个育成系的晚期叶斑病评分低于佐治亚州 12Y。在 Gibbs 农场试验中，佐治亚州 12Y 和所有育成系的产量相似。在 Lang 农场，跨年度和育成系之间，NDVI 与视觉估计的叶片损失之间的关系由两段式分段回归描述，其中 NDVI 随着叶片损失的增加而更快地下降，大约在 89%以上。NDVI 用于比较育成系之间的斑点的效用似乎仅限于叶片损失存在差异的情况。佐治亚州 12Y 和评估的多个育成系具有在有机生产等情况下使用的潜力，因为可用的种子处理和叶斑病防治的可接受杀菌剂有限。
