Fall Panicum has shown some resistance to Atrazine® and related herbicides, and is one of the most competitive grass weeds in North America. It is most often a problem in reduced or non-tilled fields whose undisturbed soils are favorable for germination. The species P. dichotomiflorum is a summer annual with large, round, smooth sheaths that are commonly bent at the nodes. This grassy weed can reach up to 210 cm at maturity and forms a zigzagged pattern in its stem, which aids in the identification of this species.
The seedling of fall Panicum is distinctly hairy on the lower surface of the leaf blades and the seedling has no auricles.
The mature plant of fall Panicum has leaves that are smooth with a conspicuous middle vein. The stems are also smooth, round and slightly glossy. The nodes are swollen and bend in varying directions causing the plants distinct zigzag growth pattern. The flowers are in the form of a wide seed head that has a purplish tint. It is easy to mistake fall Panicum for barnyard grass; however, the key distinguishing feature between the two species, is the production of a seed head by the species P. dichotomiflorum.
Optimal growth conditions
The species P. dichotomiflorum is capable of growing in a wide variety of soils, from clay to silty loamy soils.