Ascochyta blight of faba bean, caused by Ascochyta fabae (teleomorph: Didymella fabae) is one of the most destructive diseases of faba bean in Tunisia. Temporal and spatial development of ascochyta blight were studied and characterized during 2010–2011 and 2011–2012 in three faba bean fields located in Oued Mliz, Oued Beja and Mornag, using mathematical and geostatistical analyses. Mass Disease Index (MDI) was assessed every two weeks in each quadrat located around the central source of inoculum. Richards’ function well described disease progress in all sites except for Oued Beja in 2011–2012, the shape parameter m is significantly close to 1 placing the model in its particular form of Gompertz and confirming the polycyclic characteristic of the epidemic. Empirical analysis showed that the effect to locations on epidemic dynamics was explained by highly significant environmental effect (temperature, rain events). These differences in epidemic dynamics were confirmed by the analysis of parameters estimated by the Richards’ model (average relative disease progression rate (rw), proportional average relative disease progression rate (rwp), maximum disease progression rate at inflection point (ri), time at inflection point (ti), MDI at the inflection point (yi)). Analyzing the spatial structure dynamics of the disease using Lloyed Index of Patchiness (LIP) and the mapped disease distribution at different dates showed that LIP was estimated by an exponential functionthat decreased over time in all sites and seasons. LIP dropped below 1 (limit value for aggregated distribution) after 12, 25, 30, 36 and 48 daysat Oued Beja and Oued Mliz during both seasons and during the second season in Mornag. After these periods, the disease distribution is randomly distributed. However, according to the mapping, disease distribution was aggregated in terms of severity even at the end of the epidemics, indicating different temporal dynamics such as changes in distance from the inoculum source.

中文翻译：

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由豆荚壳菌引起的子壳菌病的时空动态。在突尼斯的蚕豆田

蚕豆子叶枯病是突尼斯蚕豆病害中最具破坏性的病害之一，由蚕豆子壳菌（端胚型：Didymella fabae）引起。2010-2011 年和 2011-2012 年期间，在位于 Oued Mliz、Oued Beja 和 Mornag 的三个蚕豆田中，使用数学和地质统计分析研究和表征了子囊枯病的时空发展。在位于接种物中心源周围的每个样方中，每两周评估一次大规模疾病指数 (MDI)。Richards 的函数很好地描述了 2011-2012 年除 Oued Beja 之外的所有地点的疾病进展，形状参数 m 显着接近 1，将模型置于其特定形式的 Gompertz 并证实了流行的多环特征。实证分析表明，位置对流行动态的影响可以通过非常显着的环境影响（温度、降雨事件）来解释。这些流行动态的差异通过对理查兹模型估计的参数（平均相对疾病进展率 (rw)、比例平均相对疾病进展率 (rwp)、拐点处的最大疾病进展率 (ri)、时间）的分析得到证实。在拐点 (ti)，MDI 在拐点 (yi))。使用劳埃德斑块指数 (LIP) 和绘制的不同日期的疾病分布分析疾病的空间结构动态表明，LIP 是通过指数函数估计的，该函数在所有地点和季节都随时间下降。LIP 在 12、25、30、Oued Beja 和 Oued Mliz 两个赛季和第二个赛季在 Mornag 的时间为 36 天和 48 天。在这些时期之后，疾病分布是随机分布的。然而，根据绘图，即使在流行结束时，疾病分布也按严重程度汇总，表明不同的时间动态，例如距接种源距离的变化。