The Strategy - Orange Hawkweed (Hieracium aurantiacum) is a relative of the sunflower plant a native plant to Europe. It appears to have been spread by people who love the beautiful orange flowers. The problem is that the plant spreads not only by seed but also by stolons (above ground) and rhizomes (below ground) which means this plant can spread almost anywhere it wishes. This is the only member of the hawkweed family that has red-orange flowers, all the others are yellow. Plants produce a basal rosette of leaves which produce bristly stems that are mostly leafless. The stems and leaves exude a milky latex when cut or broken. This plant has not been found in our area but is abundant in northern Idaho counties, western Wyoming, and Washington State.
The Attack - This plant generally inhabits riparian areas (streams, ditches, and the like) but mostly it likes moist grasslands or forest edges. As the plant is built to develop anywhere and spreads even worse, it is extremely competitive toward the native species. Livestock will not graze on the plant and like many other weeds they tend to overgraze the desirable plants, which allows the invader to grow stronger.
The Defense - Mechanical control is not much of an option when dealing with established weeds of this type. If there is just one or two plants then by all means please just dig them up. Once the plants become established then one needs to use specialty herbicides such as Milestone or Chaparral, Transline, Curtail, or even Tordon 22K. Apply in the spring when the plants are young, or in the fall when they are preparing for the winter. To find these products or for proper identification call your local county weed superintendent.
PLEASE NOTE -The proper use and application of herbicides can be an effective way to control and eradicate noxious and invasive plants. Before using herbicides, always carefully follow the label and safety instructions on the label. While we recommend the use of herbicides as one of the effective tools for integrated pest management, the Idaho Weed Awareness Campaign assumes no liability for herbicide applications.
For more information, click on the link below to download the Idaho's Noxious Weeds Control Guidelines publication produced by the University of Idaho Extension.
U of I Idaho's Noxious Weeds Control Guidelines (183 KB PDF download)