Orange hawkweed in a wildflower meadow. 

Noxious & Invasive Plants of Alaska

NOXIOUS OR INVASIVE PLANTS…

…MORE THAN JUST YOUR COMMON

 GARDEN WEEDS! 

These plants can: 

Endanger wildflower meadows

        Degrade stream banks, 

                Replace wildlife habitat, 

Reduce quality of livestock feed, and take over your lawn!

Invasive plants are those species whose growth and reproductive habits combined with lack of their native control agents (diseases, insects, herbivores, etc.) allow them to out-compete and replace native plant species.  All of the species listed here have the potential to impact Kodiak’s natural environment if they are allowed to establish and spread beyond the urban landscape.

Presidential executive order 13112:

Invasive species are “alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.”

Orange hawkweed (Hieracium aurantiacum) – This species was probably brought to Kodiak in the mid 1960s as an ornamental flower. Major infestations now occur throughout Kodiak and two villages of the archipelago.  Other infestations are still being identified and mapped. This species has invaded roadsides, residential lawns, gardens, parks, native wildflower meadows and shrub habitat. The Kodiak National Wildlife Refuge began an eradication effort in Fall 2002 for an infestation of orange hawkweed on Camp Island in Karluk lake.  This project has been used as an example for others in the state of Alaska and was the impetus for other invasive plant activities on the archipelago including surveys and eradication efforts coordinated through the Kodiak Soil and Water Conservation District.

Japanese knotweed (Polygonum cuspidatum) – This species was also brought in as an ornamental.  Initial surveys indicate it is currently confined to residential areas but conversations continue to find new infestations recently transplanted to sites outside the city limits, including a remote lodge and a cabin site on the south end of Kodiak Island. Gardeners are beginning to realize the invasive potential of this species and some are attempting to eradicate their infestations.  Southeast Alaska and Northwest Washington are both examples of areas with major knotweed infestations along rivers with climate, habitat and salmon runs similar to Kodiak.

Oxeye daisy (Leucanthemum vulgare or Chrysanthemum leucanthemum) – Still considered a pretty garden flower by many people, this species has become the dominant flower at Kodiak National Wildlife Refuge headquarters.  It is taking over several of the archipelago’s cemeteries, and is spreading along ditches in at least one village.  Oxeye daisy has been introduced through use of so-called “wildflower” seed mixes and in past years has been sold at local garden club plant sales.  The Refuge has started a control effort at their headquarters on Buskin River road where they hope to re-establish native forbs.

A few other ornamental garden species known to be invasive and present in Kodiak include: Yellow toadflax (Linaria vulgaris), Dame’s rocket (Hesperis matronalis), and Foxglove (Digitalis purpurea).  Escaped infestations of each of these species have been observed in residential areas but comprehensive surveys have not been conducted to document actual occurrence in all areas. Remote villages, lodges and cabin sites around the archipelago leave Kodiak’s wild lands and wildlife habitat vulnerable to infestations if (when) these species do spread. Public education is ongoing and includes messages to “control aggressive plants” and “be a responsible plant owner” but currently there are no Alaska state laws banning the distribution of known invasive plants.

Canada thistle (Cirsium arvense) – Several infestations of this prickly species are present in the Kodiak archipelago.  Canada thistle was probably brought to remote sites by homesteaders as early as the 1940s with livestock and hay. Horse manure is a common method for this species to spread but seeds can also be introduced with potted plants from “Outside” nurseries. A few infestations “have been here for years and haven’t gone anywhere” - this observation (opinion) limits incentive for private landowners to treat their infestations. Public education continues on this subject.  Invasive species have been known to exist for several years until they acclimate to local conditions, conditions change in their favor (warm winter, etc.) or their population reaches a point where the infestations are able to reproduce exponentially.  Roadside and ditch maintenance activities can also help spread invasive species.

Bull thistle (Cirsuim vulgare) – Recently discovered infestations of bull thistle along the Kodiak road system suggest that hay bales brought in for erosion control during road construction activities have apparently spread this species. It has also been accidentally spread with gravel used for maintenance at a Kodiak airport.

Kodiak SWCD would like to express our appreciation to the U.S. Fish & Wildlife Service for their continued generous financial support for our Noxious and Invasive Plants Program.

 Partners for Fish & Wildlife Grant Program.