During this season in Missouri, many pastures grapple with the dominance of annual grass weeds such as crabgrass and yellow foxtail. Recently, another, less common foxtail species has been observed - the knotroot foxtail, scientifically known as Setaria parviflora. It closely resembles yellow foxtail but possesses distinct characteristics, primarily short, knotty rhizomes, making it a perennial weed.
Knotroot foxtail's seedheads are similar to those of yellow foxtail, with straight stems and yellow bristles. What sets it apart is the presence of these short, knotted rhizomes. Though it's been present in Missouri for some time, it hasn't been commonly noticed in pastures until the past few seasons.
This less-known foxtail species has been identified in various Missouri counties, including Bates, Cape Girardeau, and Moniteau. The Flora of Missouri indicates its distribution across approximately two-thirds of the state.
Controlling knotroot foxtail in tall fescue pastures presents challenges due to limited herbicidal options. There's minimal research available on its control, and current herbicides don't selectively target it, often harming desirable grasses and legumes as well. Glyphosate can be spot applied but requires caution to avoid harming other forages.
For growers with sporadic infestations, mechanical removal or glyphosate spot treatments before seed production may be effective. Cultural control methods, such as maintaining competitive forage through proper pH, fertility, and grazing management, are also vital. Vigilance is key, as preventing its establishment is easier than eradication. Inspect fields, fencerows, and roadsides for knotroot foxtail, and check purchased hay for contamination.
If you encounter knotroot foxtail, reporting it can contribute to better understanding its distribution in Missouri.
Photo Credit: MAFRI
Categories: Missouri, Livestock