Orange hawkweed, if you have it you’ll know it. This dainty little orange flowered plant is pound for pound one of the most aggressive invasive weeds in Alaska. Lawns, hayfields, pastures, and grassy meadows are are all taken over by orange hawkweed quickly and thoroughly.

Orange hawkweed infestation on Camp Island within the Kodiak National Wildlife Refuge.

How does hawkweed do it? First, hawkweed aggressively spreads with creeping roots, and stolons (above ground stems).  Second, seeds are wind dispersed, and viable even when they are not fertilized because of a characteristic known as apomixis. Finally, orange hawkweed is allelopathic, meaning it produces chemicals that work like herbicides stressing plants to the point that the competition for space is won by orange hawkweed.

Hawkweed has proven time and time again in Alaska, that if it can find a sunny spot it will dominate the vegetation. Reducing forage quantity and quality for farmers, aggressively out competing native vegetation, and forming monocultures in the process, orange hawkweed is a plant you want to get on top of before it is too late.    

Control of orange hawkweed is not simple or straightforward. Those roots that creep through the ground are composed of numerous fibrous segments that if split easily, and when left behind they form a new plant. When pulled or dug up hawkweed often comes back just as numerous as before you did anything. Killing the roots and doing as little soil disturbance as possible is key to managing orange hawkweed, and for all but the smallest of infestations this means using an appropriate herbicide.

Herbicide management of orange hawkweed is ideally done early in the season after it starts to grow, but before it is flowering. Later applications will show results, but are less effective in the long term. A surfactant (additive that breaks water viscosity) should be used with liquid herbicides because hawkweed is covered with small hairs that prevent herbicides from touching the leaf and stem tissue.  For more information on controlling orange hawkweed see our publication “Control of orange hawkweed’.

Cover of the newest orange hawkweed control publication from the University of Alaska Cooperative Extension Service

Orange hawkweed is the only orange to red flowered sunflower family plant that has spread in Alaska. If you see orange hawkweed on public land use our mobile application “Alaska Weeds ID’ to report the location.  If you think you have orange hawkweed on your property you can use the “Alaska Weeds ID’ app to get identification help, and sending a report will get you in touch with an expert with the Cooperative Extension Service or a colleague that can provide you with advice on controlling it. Orange hawkweed has never been seen north of the Alaska Range, so if you spot it up there let us know.