Phytopathology. 1998 Jun;88(6):536-43. doi: 10.1094/PHYTO.1998.88.6.536.
ABSTRACT A rain simulator, with generated rains of 11 and 30 mm/h, was used to determine the effect of a cover crop or intercrop on the splash dispersal of Colletotrichum acutatum conidia. Dispersal through sudangrass, which can be used as a 'living mulch', was tested at two planting densities (140 or 280 kg/ha) and two heights (5 and 20 cm) and compared with a control consisting of a bare soil. Dispersal of C. acutatum conidia was assessed by counting colonies formed from spore-bearing splash droplets deposited in sheltered petri plates containing a selective medium. Both a cover crop and rain intensity significantly affected splash dispersal as measured by the interpolated total number of colonies (denoted by Sigma) from 0 to 72 cm from the inoculum source and in a time span of 61 min of generated rain (P < 0.001). However, there was no significant interaction of cover crop and intensity (P > 0.90). Dispersal with a 30-mm/h rain was higher than dispersal with a 11-mm/h rain, and presence of a cover crop significantly reduced dispersal compared with bare soil (P < 0.001). Of the treatments with sudangrass, cover crop planting density did not affect dispersal overall, but there was greater spore dispersal with the taller sudangrass at the higher planting density, due in part to the higher rate of water splashing with the tall grass compared with the short grass. Spore deposition in the petri plates could be functionally related to distance and time using a diffusion-type model, and parameter estimates could be used to explain the effects of cover crop on Sigma. Although the relationship between cover crop properties and splash dispersal is complex, results show the potential beneficial effects of the cover crop on disease management.
摘要 利用 11 和 30 毫米/小时的降雨模拟器，研究了覆盖作物或间作对炭疽菌分生孢子飞溅扩散的影响。在两种种植密度（140 或 280 公斤/公顷）和两种高度（5 和 20 厘米）下，测试了利用苏丹草作为“活覆盖”的飞溅扩散情况，并与裸露土壤的对照进行了比较。通过计数含有选择性培养基的遮蔽培养皿中沉积的带孢子飞溅液滴中形成的菌落来评估炭疽菌分生孢子的扩散情况。覆盖作物和降雨强度都会显著影响飞溅扩散，这可以通过从接种源 0 到 72 厘米范围内的菌落总数（表示为 Sigma）和 61 分钟生成雨的时间范围内来衡量（P < 0.001）。但是，覆盖作物和强度之间没有显著的交互作用（P > 0.90）。30 毫米/小时的降雨比 11 毫米/小时的降雨具有更高的传播性，与裸露土壤相比，覆盖作物的存在显著降低了传播性（P < 0.001）。在苏丹草处理中，覆盖作物种植密度对总体传播没有影响，但在较高的种植密度下，较高的苏丹草传播的孢子更多，这部分是由于与矮草相比，高草的溅水率更高。培养皿中的孢子沉积可以通过扩散模型与距离和时间相关联，参数估计可以用来解释覆盖作物对 Sigma 的影响。尽管覆盖作物特性和飞溅传播之间的关系很复杂，但结果表明覆盖作物对疾病管理具有潜在的有益影响。
