RBCA’s weed work summary

RBCA has been working with numerous partner organizations to control Invasive Plant (IP) infestations in the Seward area for five years. Our focus is addressing infestations that would have significant impacts to fish and wildlife habitat if not controlled.

To insure that we are working on the infestations of highest concern, RBCA has teamed with a very effective group called the Kenai Peninsula Cooperative Weed Management Area (add KP-CWMA website link here). For maps and photos of the Seward area IP infestations and RBCA’s projects click
here to view a PowerPoint presentation.

Seward Highway white sweetclover
In August of 2008, RBCA was alerted of a major white sweetclover (WSC) infestation along the Seward Highway. Plants introduced during a highway project two years earlier were approaching maturity and about to release thousands of seeds. RBCA conducted several volunteer weed pulls, filling eight large trailer loads that were hauled to the dump burn pile. Hundreds of plants were harvested and thousands ng the highway. An infestation that could have exploded was fully controlled.
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Sweet clover removed from the edges of the Seward Highway

Resurrection River islet WSC
White sweetclover (WSC), although beneficial elsewhere, is a very aggressive weed in Alaska with one of the highest invasiveness rankings (per the Alaska Natural Heritage Program, http://aknhp.uaa.alaska.edu/). WSC has been documented in taking over extensive open gravel areas in several of Alaska’s braided river systems. We found a small islet in the Resurrection River (adjacent to the Windsong Lodge) that was heavily infested. It had likely been introduced there by asphalt batch plant equipment several years prior. The two-acre islet was 80% covered with thick bushy WSC plants, which were already starting to spread off of the islet. For three seasons RBCA and the Homer Soil and Water Conservation District (HSWCD) Youth Weed Team hand-pulled every WSC plant found. In each of these years, thousands of plants were harvested. On the fourth year, the plant numbers had dropped to about 1,000 plants. In 2012, we harvested several hundred plants. This infestation, in the middle of a pristine salmon river, has been brought under control and another invasive plant explosion was prevented.
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Sweet Clover removed from the middle of the Resurrection River corridor

Middle School bird vetch
While Seward has several small patches of another aggressive species, bird vetch, an infestation at the Middle School is threatening to grow out of control. This infestation covers the entire length of the western and northern edge of the schoolyard, and is spreading onto adjacent properties. Hand-pulling can stop seed production, but does not kill the plant. For five years RBCA, the HSWCD, and the Alaska Association of Conservation Districts harvested all of these plants to slow its spread.

The only way to fully control it is to either spray it with herbicides, dig up all the soil and dispose of it, or cover it with a sun-blocking fabric for at least two years. RBCA is opposed to using toxic chemicals in our environment. Even trace amounts of toxins can cause negative impacts to wildlife and humans. Plus, two of Seward’s domestic water wells are located within a hundred yards of this infestation. Digging up all of the soil within the five- acre infestation would
not be cost efficient. We have learned from other projects that covering the plants with a light-blocking fabric is subject to complaints about the visual impacts.

But we haven’t given up hope! A new Seward Schoolyard Habitat program, initiated by the US Fish & Wildlife Service and RBCA, will look at alternative plans for bird vetch control. One option would be to cover small, rotating sections of the infestation annually. While the whole infestation would not be controlled all at once, we could treat manageable sections without large unsightly tarped areas and still prevent it from exploding.

Exit Glacier Road Hawkbit
RBCA has also spent considerable time on hawkbit (also called fall dandelion) along the first two miles of the Exit Glacier (Herman Leirer) Rd. It can form extremely dense mats that choke out all other plants. We do not want this plant to begin spreading up and down the Resurrection River.

In 2010, we found a dense half-acre patch on private property at mile 1.7. After consulting with specialists it was determined that covering this area to deprive the hawkbit of sunlight would be the best method of control. The property owner did not want to look at black tarps for two years, so we imported weed-free topsoil and replanted the entire half-acre area. After one year only a few hawkbit plants were found at this site.
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Local volunteers tackle and subdue renegade hawkbit on the Exit Glacier road

We also used the assistance of several traveling youth/educational groups to help control some of the other smaller patches. While hand-digging this plant does limit growth, we have found that there are still lots of seeds in the soil and the plants quickly reemerge. It may be more effective to repeat the tarping process at the other infestation patches. This was done with funding from the US Fish & Wildlife Service.

In the past 5 years RBCA has worked to control several other Seward area infestations. Most of these are illustrated in the above-referenced PowerPoint slide show. Unfortunately there are still IP species that are completely out of control in town and along area roads. These include oxeye daisy, butter & eggs, creeping and tall buttercup, and of course dandelion. Please be aware that these are indeed invasive plants, often mistaken for Alaska wildflowers. Although we can’t hope to ever eradicate these plants, we can help our ecosystem by pulling them from our lawns, gardens, and roadsides, and not encourage their spread.

To learn more about Alaska’s invasive plants and to view distribution maps (AK-EPIC) visit the Alaska Natural Heritage Program website at
http://aknhp.uaa.alaska.edu/ .
RBCA’s primary IP partners include the Alaska Association of Conservation District (AACD) and the US Fish & Wildlife Service. Other project partners include the, US Forest Service, Kenai Fjords National Park, Homer SWCD, Kenai SWCD, Kenai Watershed Forum, Alaska Department of Transportation, City of Seward, Alaska SeaLife Center, the UAF Seward Marine Center.