Fall panicum Panicum dichotomiflorum Michx.
Life cycle: Annual
Native status: Native to North America
Habitat: Crop fields, waste areas
General description: Erect to decumbent growth habit, reaching heights of 4 ft. Stems often angled at nodes, resulting in ‘zig-zag’ growth habit. Seedhead is a large, spreading panicle.
Key ID traits: Hairy ligule; glabrous leaf sheaths and blades; swollen nodes; prominent light colored leaf midrib.
Similar species: Seedlings of green foxtail are similar to fall panicum in that they both have hairy ligules and lack hairs on leaf sheaths and blades. The margins of green foxtail sheaths have hairs, whereas those of fall panicum don’t.
Miscellaneous: Fall panicum became a significant problem in corn fields in the 1950’s when farmers relied heavily on the triazine herbicides (atrazine, simazine, etc.). The introduction of amide herbicides (alachlor, metolachlor, etc.) greatly reduced its prevalence. Fall panicum emerges later than the foxtails and woolly cupgrass, this provides the crop a headstart and reduces problems with fall panicum. Now fall panicum is more of a problem in corn seed production due to lack of crop canopy.