Fireweed: a Pasture Weed that will Light You Up!
Fireweed is growing well in the Panhandle and I have had a couple of calls this week regarding this plant. This winter annual stinging nettle will definitely light you up! I remember the first time I ever encountered Fireweed (Urtica chamaedryoides) while working on fence adjacent to my dad’s cow pens! It was not a pleasant experience! Contact with this nettle results in burning, agonizing pain. Red, raised welts persist for several hours – the severity of which depends on the body part affected, the length of contact, the size of the plants, and individual response.
Typically found in pastures and bare ground areas such as holding pens under trees and along fence rows, this weed can be a real nuisance. Fireweed is particularly troublesome because it possesses stinging hairs that easily embed in skin. Once exposed to the toxin, severe irritation can occur for several hours. Though generally avoided by cattle, horses are more likely to browse fireweed and develop stress symptoms. These symptoms commonly manifest themselves as weight loss, or difficulty in swallowing and breathing for many days after consumption. In extreme cases, young horses have died after rolling in fireweed and becoming over-exposed to the toxins in the leaf hairs.
Now is the time to be scouting for this weed. Research done by University of Florida Weed Management Specialists, Dr. Jay Ferrell and Dr. Brent Sellers, found GrazonNext HL, Remedy Ultra, and Pasturegard HL to be highly effective for control. Within 2 weeks of application, over 90% of the fireweed plants were dead, and the remaining individuals were yellow and dying. By 6 weeks after treatment, no fireweed could be found. Recommended rates for these herbicides are Remedy Ultra at 1qt./acre, Paturegard HL at 24 oz., and GrazonNext at 24.oz/ acre.
For more information see Fireweed (Heartleaf Nettle) Control in Pastures from our UF/IFAS Extension Weed Specialists.