Looks like you've got SOME RUST

摘要

Grasses are beautiful, low-maintenance landscape plants that have been promoted as pest free. Unfortunately, no plant is completely free from disease or insects. A fungal disease called rust is commonly reported on landscape ornamental grasses. Rust fungi (Puccinia spp. or Uromyces spp.) infect a wide variety of grasses. The ornamental grasses most affected by rust include feather reed grass (Calamagrostis x acutifbra and cvs., USDA Hardiness Zones 4-9), switchgrass [Pancium virgatum cvs., Zones 4-9), big bluestem [Andropogon gerardii and cvs., Zones 2-9), and little bluestem (Schizachyrium scoparium and cvs., Zones 2-9).