Phytopathology. 1999 Oct;89(10):954-61. doi: 10.1094/PHYTO.1999.89.10.954.
ABSTRACT Take-all, caused by Gaeumannomyces graminis var. tritici, is a damaging disease of wheat that remains difficult to control. The efficacy of an experimental fungicide, applied as a seed treatment, was evaluated in five naturally infested field experiments conducted during three cropping seasons. Plants were sampled and assessed for take-all incidence and severity at different growth stages. Nonlinear models expressing disease variables as a function of degree-days were fitted to the observed data. The incidence equation involved two parameters reflecting the importance of primary and secondary infection cycles. The earliness of infection was identified as an important variable to interpret the effects of the fungicide. In an early epidemic, the fungicide significantly reduced take-all incidence during all or most of the cropping season, whereas in late epidemics, it provided only moderate reductions of incidence. The seed treatment reduced incidence by delaying the primary infection cycle. The fungicide significantly reduced severity during the whole epidemic. It appeared more efficient in limiting root-to-root spread than in slowing down the extension of necrosis on diseased roots.
摘要 小麦全蚀病由禾顶囊壳菌小麦变种引起，是一种严重危害小麦的病害，目前仍难以防治。在三个种植季节的五次自然发病田间试验中，评估了一种实验性杀菌剂作为种子处理的效果。在不同的生长阶段，对植株进行采样并评估全蚀病的发病率和严重度。将病害变量表示为度日函数的非线性模型拟合到观测数据中。发病率方程涉及两个参数，反映了原发性和次生性侵染循环的重要性。侵染的早期被认为是解释杀菌剂效果的一个重要变量。在早期流行期，杀菌剂在整个或大部分种植季节显著降低了全蚀病的发病率，而在晚期流行期，仅适度降低了发病率。种子处理通过延迟原发性侵染循环来降低发病率。杀菌剂在整个流行期都显著降低了严重度。它在限制病根间的扩展方面比减缓病根坏死的扩展更为有效。
