Species in the Panicum genus are often hairy and have diffuse seed heads. There are three problem Panicum species in our area, two summer annuals (fall panicum and witchgrass) and a perennial species (switchgrass).
Fall panicum (Panicum dichtomiflorum)
Switchgrass (Panicum virgatum)
Witchgrass (Panicum capillare)
Similar species
Table 8: Compares the Panicums: fall panicum (Panicum dichtomiflorum), switchgrass (Panicum virgatum), and witchgrass (Panicum capillare) illustrating their similarities and differences.
| Species | Fall panicum (Panicum dichtomiflorum) | Switchgrass (Panicum virgatum) | Witchgrass (Panicum capillare) |
|---|---|---|---|
| Similarities | Summer annual; leaf bud rolled; no auricle; ligule fringe of hairs; fibrous root system | Leaf bud rolled; no auricle; ligule fringe of hairs | Summer annual; leaf bud rolled; no auricle; ligule fringe of hairs; fibrous root system |
| Differences | Seedling leaf sheaths are densely hairy, blades are hairy on lower surface; mature blades and sheaths are smooth on both surfaces. | Perennial; leaf blade is hairy on upper side; sheath is hairy at margins; it produces rhizomes | Seedling sheath, blade, and collar are densely hairy; on mature plant, leaf blades on both surfaces and leaf sheaths are densely hairy |
Herbicide resistance in panicum species
Reported as of 2021:
See fall panicum, switchgrass, and witchgrass pages in their respective reference sections for more details on resistance or visit the International Herbicide-Resistant Weed Database homepage for more information on resistance.