The leaf rust pathogen Thekopsora minima of highbush blueberries (Vaccinium corymbosum) was detected for the first time in Germany in 2015, in two nurseries in Lower Saxony. One introduction was related to recent import of plants from the USA, but the source of the other outbreak was unclear. In 2016, intensive surveillance was conducted of garden centres, tree nurseries, blueberry plantings, neglected plantings and volunteer blueberries growing in close proximity to commercial plantings. T. minima infections were found only on wild plants or neglected plants, in three different rural districts of Lower Saxony. In addition, proof was found of T. minima being present in Lower Saxony since at least 2011. Uredinia and urediniospores were the only developmental stages observed, providing strong evidence of subsequent infection cycles of urediniospores of T. minima able to survive German winter conditions without a host change. Experiments revealed urediniospore infections of the outer bud leaves or pherophylls only, with no disease symptoms on the innermost leaves. Removing diseased leaves accompanied by fungicide treatment was an effective measure to eliminate T. minima. Susceptibility of 14 V. corymbosum varieties under natural conditions was assessed during surveillance. ‘Bluecrop’, ‘Blue Bayou’, ‘Goldtraube’, ‘Poppins’ and ‘Reka’ were found to develop severe symptoms, while ‘Cipria’, ‘Denise Blue’, ‘Liberty’ and ‘Pink Icing’ showed intermediate symptoms and ‘Aurora’, ‘Blueberry Glaze’, ‘Duke’, ‘Jelly Bean’ and ‘Peach Sorbet’ remained symptomless. Possible routes of introduction of the pathogen, its survival and the role of volunteer blueberries in prevalence of T. minima are discussed.

中文翻译：

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2015-2016年下萨克森州高灌木蓝莓上Thekopsora minima的发生：流行，品种易感性和感染生物学的某些方面

2015年在德国下萨克森州的两个苗圃中首次发现了高灌木蓝莓（Vaccinium corymbosum）的叶锈病病原菌Thekopsora minima。一个介绍与最近从美国进口的植物有关，但另一个爆发的来源尚不清楚。2016年，对商业中心附近种植的花园中心，苗圃，蓝莓种植，被忽视的种植以及自愿性蓝莓进行了严格的监控。在下萨克森州的三个不同的农村地区，仅在野生植物或被忽视的植物上发现了极小锥虫感染。另外，发现了最小的T.至少自2011年以来一直存在于下萨克森州。观察到的仅有乌迪丁菌和urediosiospores，这有力证明了T. minima的utiiosiospores后续感染周期能够在德国冬季条件下生存而无寄主改变。实验表明，仅外芽叶或叶绿素可感染梭菌，而最内层叶无病征。去除病害的叶片并进行杀菌处理是消除极小T.的有效措施。14 V.Corymbosum的易感性 在监测期间评估了自然条件下的品种。发现“ Bluecrop”，“ Blue Bayou”，“ Goldtraube”，“ Poppins”和“ Reka”会出现严重症状，而“ Cipria”，“ Denise Blue”，“自由”和“ Pink Icing”显示出中等症状，而“ “极光”，“蓝莓釉”，“杜克”，“果冻豆”和“桃冰糕”仍然没有症状。讨论了病原体引入的可能途径，其存活以及自发性蓝莓在最小螺旋杆菌流行中的作用。