Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA.
J R Soc Interface. 2020 Jul;17(168):20200337. doi: 10.1098/rsif.2020.0337. Epub 2020 Jul 15.
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.
小麦受到叶锈病等疾病的威胁。疾病传播的一个重要机制是由于雨水飞溅而释放和分散锈孢子。然而，尚不清楚带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片上。在这里，我们表明飞溅液滴要么反弹，要么附着，这取决于叶片的方向以及叶片表面是否经过杀菌剂处理。一个标度模型表明，当液滴的动能超过其对表面的钉扎能时，反弹就会发生。我们的研究结果表明，具有讽刺意味的是，杀菌剂的应用虽然可以保护小麦植株免受病害的侵害，但也可能通过使叶片对带孢子的液滴具有粘性，从而促进病原体的传播和感染。
