Verticillium wilt, caused by the soil-borne fungus Verticillium dahliae, is one of the most harmful diseases in Mediterranean olive-growing areas. Although, the effects of both soil temperature and moisture on V. dahliae are well known, there is scant knowledge about what climatic drivers affect the occurrence of the pathogen on a landscape scale. Here, we investigate what climatic drivers determine V. dahliae occurrence in olive-growing areas in southern Spain. In order to bridge this gap in knowledge, a landscape-scale field survey was carried out to collect data on the occurrence of V. dahliae in 779 olive groves in Granada province. Forty models based on competing combinations of climatic variables were fitted and evaluated using information-theoretic methods. A model that included a multiplicative combination of seasonal and extreme climatic variables was found to be the most viable one. Isothermality and the seasonal distribution of precipitation were the most important variables influencing the occurrence of the pathogen. The isothermal effect was in turn modulated by the seasonality of rainfall, and this became less negative as seasonality increases. Thus, V. dahliae occurs more frequently in olive-growing areas where the day-night temperature oscillation is lower than the summer-winter one. We also found that irrigation reduced the influence of isothermality on occurrence. Our results demonstrate that long-term “sophisticated” climatic factors rather than “primary” variables, such as annual trends, can better explain the spatial patterns of V. dahliae occurrence in Mediterranean, southern Spain. One important implication of our study is that appropriate irrigation management, when temperature oscillation approaches optimal conditions for V. dahliae to thrive, may reduce the appearance of symptoms in olive trees.

中文翻译：

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黄萎病的气候驱动因素在西班牙南部的地中海橄榄产区

黄土黄萎病是由土壤传播的真菌黄萎病菌引起的，是地中海橄榄产区最有害的疾病之一。尽管土壤温度和水分对大丽花蛾的影响是众所周知的，但对于哪种气候驱动因素会在景观尺度上影响病原体的发生却知之甚少。在这里，我们调查了哪些气候驱动因素决定了西班牙南部橄榄种植区的大丽花弧菌的发生。为了弥合这一知识鸿沟，进行了景观规模的实地调查，以收集有关大丽花弧菌发生的数据在格拉纳达省的779个橄榄树林中。使用信息理论方法对40个基于竞争性气候变量组合的模型进行拟合和评估。发现包括季节性和极端气候变量的乘法组合的模型是最可行的模型。等温和降水的季节分布是影响病原体发生的最重要变量。反过来，等温效应又受降雨季节的影响，随着季节的增加，这种影响变得越来越小。因此，V。dahliae在橄榄生长的地区，这种现象更常见，白天白天的温度波动低于夏季冬天的温度。我们还发现灌溉减少了等温对发生的影响。我们的结果表明，长期的“复杂”气候因素而非“主要”变量（例如年度趋势）可以更好地解释西班牙南部地中海地区大丽花弧菌的发生空间格局。我们的研究的一个重要意义是，当温度波动接近大丽花to生长的最佳条件时，适当的灌溉管理可能会减少橄榄树中的症状出现。