Wheat is threatened by diseases such as leaf rust. One significant mechanism of disease spread is the liberation and dispersal of rust spores due to rainsplash. However, it is unclear to what extent the spore-laden splashed droplets can transmit the disease to neighbouring leaves. Here, we show that splashed droplets either bounce or stick, depending on the orientation of the leaf and whether the surface of the leaf has been treated with a fungicide. A scaling model revealed that bouncing was enabled when the droplet’s kinetic energy exceeded its pinning energy to the surface. Our findings indicate that, ironically, the application of fungicide to protect a wheat plant may also facilitate pathogen spread and infection by making leaves sticky to spore-laden droplets.

中文翻译：

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飞溅液滴对杀菌剂处理过的小麦叶片的影响

小麦受到叶锈病等疾病的威胁。疾病传播的一种重要机制是由于雨水溅洒而释放和传播锈病孢子。然而，尚不清楚载有孢子的飞溅液滴在多大程度上可以将疾病传播到邻近的叶子。在这里，我们展示了飞溅的水滴要么反弹要么粘住，这取决于叶子的方向以及叶子的表面是否已经用杀真菌剂处理过。缩放模型显示，当液滴的动能超过其对表面的钉扎能时，就会启用弹跳。我们的研究结果表明，具有讽刺意味的是，使用杀菌剂保护小麦植株也可能通过使叶子粘在载有孢子的液滴上来促进病原体的传播和感染。