Anchorage Daily News

The threat of invasive plants has made headlines recently, and this article is one in an occasional series on imported plants that have become aggressive in the local environment.

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Bird vetch was brought to Alaska from Europe almost a century ago as a potential forage crop.

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Howdy, weed warriors. This week's spotlight features bird vetch (Vicia cracca), which falls under what a co-worker calls the "rhizomacious" category of invasive plants. More on that hip-hop intellectualizing in a minute.

THE OFFENDER: BIRD VETCH

Though common as a decorative flower in hedgerows throughout Europe, bird vetch sits atop Alaska's least-wanted invasive plants list. This climbing perennial -- introduced to the state nearly a century ago as a potential forage crop -- easily survives winter and thrives in summer with as few as 110 frost-free days.

This weak-stemmed invader sprouts leaves with up to 10 pairs of narrow leaflets and bluish-purple flowers in late spring. The coiling tendrils climb and cling and often form tangled mats on fences, signposts, aspen and spruce stands, pastures, woodlands, roadways, disturbed grassy areas and even undisturbed areas. To make matters worse, the plants thrive under fire and drought conditions.

Bird vetch produces seeds prolifically and also spreads by rhizomes, horizontally creeping stems just beneath the soil. The large seeds can lay dormant in seedbeds for up to five years. Fortunately, they don't disperse easily unless tangled in vegetation clinging to maintenance equipment or introduced with topsoil.

NOXIOUS NOTORIETY: Once rooted, these beauties cling to and wrap around everything in sight, frequently killing native pants and tree limbs. They also develop a mutual dependence on certain soil bacteria and atmospheric nitrogen that can alter soil conditions.

PREVENTING THE SPREAD: Since bird vetch can grow almost anywhere in sun or shade, hand-pulling or cutting at the base of the stem can remove small infestations. But large, tangled mats will require patience and pulling several times a season over several years to stifle reproduction and exhaust the seed bank. When all else fails, break out the lawn or riding mower or tractor, or try a clopyralid herbicide.

As always, practice the EDRR method -- early detection/rapid response -- in early to mid-summer before the flowers turn to seed. This process could take a few seasons, so don't be discouraged.

MORE FLOWER FOR YOUR BOWER: Bird vetch can take a huge chunk out of the garden, so replant the area based on the amount of sunlight with such hardy perennials as lady's mantle, monkshood, columbine, English daisies, larkspur, lilies, lupine, blue poppy or phlox. In native ecosystems, such as a forest understory, encourage the spread of ferns, grasses and other groundcovers.

TRASH AND BURN: Mow them down and grind them up -- especially before the seeds start popping. Or, once they're yanked from the ground, stomp the plants flat and let them dry out. Then torch them or bag them for the trash or landfill. Most of all, avoid the compost heap, where errant seeds could thrive.

J. Mark Dudick is a media specialist in Anchorage for the UAF Cooperative Extension Service.

BIG WILD WORRIES: For more information about bird vetch or other invasive plants, call 786-6300 or log on to the Integrated Pest Management program at

www.uaf.edu/ces/cnipm

www.uaf.edu/ces/ipm/vicr.html

Download a pocket weed guide at

www.alaskainvasives.org

MARK YOUR CALENDAR: The Citizen Weed Warriors program kicks off with a party from 6 to 8 p.m. June 17 at the Lidia Selkregg Chalet in Russian Jack Springs Park, off DeBarr Road. Contact collinswa@ muni.org.

What's blooming at Alaska Botanical Garden

Flowers are popping open daily, so don't delay a visit to see what blooms early.

• Aleutian speedwell (Veronica grandiflora)

• Primula (including Primula elatior, P. veris, P. pubescens, P. allionii, P. halleri

• Leopard's bane (Doronicum officinalis)

• Anemone (including Anemone richardsonii, A. parviflora)

• Pasque flower (Pulsatilla vulgaris)

• Shooting star (Dodecantheon pulchellum)

• Marsh marigold (Caltha leptosepala)

-- information from Barbara Miller, ABG senior horticulturist Garden calendar

• Gardens: Get them in. You still have time. You still have to harden off plants, though.

• Nurseries: Great sales.

• Garden Fair: 11th annual Garden Fair and Garden Art Show is June 21-22. 11 a.m. to 6 p.m. Saturday, 11 a.m. to 5 p.m. Sunday. Admission: $5, 2 and under free. Botanical garden members' preview is 10-11 a.m. Saturday.

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