Phytopathology. 1998 Dec;88(12):1338-46. doi: 10.1094/PHYTO.1998.88.12.1338.
ABSTRACT Microplots experiments were carried out at Córdoba, southern Spain, from 1986 to 1989 to determine the effects of sowing date in the management of Fusarium wilt of chickpea as influenced by virulence of the pathogen race and by cultivar susceptibility. A total of 108 epidemics of the disease were described, analyzed, and compared to assess the degree of disease control. The epidemics were characterized by five curve elements: final disease intensity index (DII), standardized area under DII progress curve, time to epidemic onset, time to inflection point (t(ip)), and the DII value at t(ip), the last two parameters being estimates from the Richards function adjusted by nonlinear regression analysis. The structure of Fusarium wilt epidemics was examined by conducting multivariate principal components and cluster analyses. From these analyses, three factors accounting for 98 to 99% of the total variance characterized the DII progress curves and provided plausible epidemiological interpretations. The first factor included the t(ip) and the time to disease onset and can be interpreted as a positional factor over time. This factor accounted for the largest proportion of the total variance and may, therefore, be considered as the main factor for analysis of Fusarium wilt epidemics. The second factor concerns the standardized area under DII progress curves and the final DII of the epidemics. The third factor identified the uniqueness of the estimated value for the point of inflection of the DII progress curve over time. Our results indicate that for each year of experiment epidemic development was related mainly to the date of sowing. Thus, for chickpea crops in southern Spain, advancing the sowing date from early spring to early winter can slow down the development of Fusarium wilt epidemics, delay the epidemic onset, and minimize the final amount of disease. However, the net effect of this disease management practice may also be influenced, though to a lesser extent, by the susceptibility of the chickpea cultivar and the virulence and inoculum density of the Fusarium oxysporum f. sp. ciceris race.
摘要 1986 年至 1989 年，在西班牙南部的科尔多瓦进行了微型小区试验，以确定播种日期对菜豆枯萎病管理的影响，该影响受病原体小种毒力和品种易感性的影响。共描述、分析和比较了 108 次病害流行情况，以评估病害控制程度。这些流行情况的特点是五个曲线要素：最终疾病强度指数（DII）、DII 进展曲线下的标准化面积、流行开始时间、拐点时间（t(ip)）和 t(ip)时的 DII 值，后两个参数是通过非线性回归分析对调整后的 Richards 函数进行估计得到的。通过进行多元主成分和聚类分析来检查枯萎病流行的结构。从这些分析中，有三个因素占总方差的 98%至 99%，可以描述 DII 进展曲线，并提供合理的流行病学解释。第一个因素包括 t(ip)和发病时间，可以解释为随时间的位置因素。这个因素占总方差的最大比例，因此，可以被认为是分析枯萎病流行的主要因素。第二个因素涉及 DII 进展曲线下的标准化面积和流行的最终 DII。第三个因素确定了随时间变化的 DII 进展曲线拐点的估计值的独特性。我们的结果表明，对于每一年的试验，流行的发展主要与播种日期有关。因此，对于西班牙南部的菜豆作物，将播种日期从早春提前到初冬，可以减缓枯萎病流行的发展，推迟流行的开始，并将最终的病害量降到最低。然而，这种病害管理实践的净效应也可能受到菜豆品种的易感性以及尖孢镰刀菌 f. sp. ciceris 小种的毒力和接种体密度的影响，不过影响程度较小。
