In 2016, widespread dieback of Phragmites australis was reported in the Mississippi River Delta (MRD), Louisiana. We conducted two common-garden experiments to investigate several potentially important factors associated with this dieback: scale insects, water depth, fertilization and P. australis genetics (three lineages: Gulf, Delta and invasive EU). Predictions tested were scale abundance is lower in high water, at low fertilization, and for EU; plant biomass is negatively impacted by scales, high water and high fertilization; and EU suffers the least damage from the three potential stressors. Scale abundance was 41% lower in high water and decreased 2.7 fold as fertilization increased. Also, EU had 1.5–2.6 times fewer scales than Gulf, but had similar scale abundance to Delta. Impacts of scales, water depth and fertilizer on plant biomass depended strongly on lineage. Scales reduced biomass of Delta, EU and Gulf by 38%, 32% and 10%, respectively. In comparison, biomass was 30% higher for EU, 46% lower for Gulf and unchanged for Delta in high versus low water. Finally, at high fertilization levels, Gulf produced 57% more biomass than EU. Owing to its greater tolerance to scales and high water, EU may be most suitable for use in restoration of the MRD.

2016年，据报道路易斯安那州密西西比河三角洲（MRD）广泛分布了芦苇。我们进行了两个常见的花园实验，以研究与这种死亡相关的几个潜在重要因素：鳞虫，水深，施肥和南方假单胞菌遗传学（三个血统：海湾，三角洲和入侵性欧盟）。所测试的预测是，高水，低施肥和欧盟的水垢丰度较低。植物生物量受到水垢，高水和高施肥的不利影响；欧盟遭受的三种潜在压力最小。在高水中，水垢丰度降低41％，并随着施肥量的增加而降低2.7倍。同样，欧盟的规模比海湾地区少1.5-2.6倍，但规模丰度与三角洲相似。鳞片，水深和肥料对植物生物量的影响主要取决于谱系。规模使三角洲，欧盟和海湾地区的生物量分别减少了38％，32％和10％。相比之下，高水和低水相比，欧盟的生物量高30％，海湾的生物量低46％，三角洲的生物量却没有变化。最后，在高施肥水平下，海湾地区的生物量比欧盟多57％。