By Mindy Hittle-McNair
There is a problematic winter annual found on bare-ground, along tree lines and under fences. Urtica chamaedryoides is also called fireweed, heartleaf nettle, weak nettle. It is a native Florida species.
Fireweed's range extends from south Florida to southern Ohio, Kentucky, southern Illinois, to southeastern Kansas, Texas, Louisiana and Mexico. The Florida's Urtica species is troublesome because of the stinging hairs.
Humans and animals will have a wide range of reactions to this plant. The hairs on the plant inject irritants that are very painful. Cattle generally avoid this plant, but horses have been know to accidentally browse or roll in the plant causing minor to extreme irritation.
Controlling this plant is a challenge. Mowing appears to provide no control of this species. The seed is surrounded by a sticky substance that can be transported by mower blades to areas not infested with this weed.
At this time herbicides are the best way to treat pastures and growers have choice. GrazonNext, Remedy or Pasturegard provide the best control of this weed and are safe to use in pastures. Using these specific chemicals on this weed can take up to two weeks for the weeds to turn yellow and die.
Timeliness is critical for managing this pasture weed. Urtica species start to die off and disappear with the onset of warmer temperatures and the summer season, so spray early to prevent further seed production. A quart of Remedy and GrazonNext per acre and 1.5 quarts of Pasturegard are recommended to control this weed.
There are no grazing restrictions for beef cattle with these herbicides, but lactating dairy animals must be removed for 0 and 14 days with GrazonNext and Remedy, respectively, and one season from Pasturegard.
McNair is the University of Florida Extension agent in Walton County.