Three Weeds Most Wanted — DEAD!
by Jeanne DeBenedetti Keyes
Every gardener has a hit list for weeds. Since each garden is different, that list may vary but I’ll wager that my three most wanted are at least in the Top Ten for all Pacific Northwest Gardeners, if not also on the invasive species list.
I’ll start with shotweed (Cardamine oligosperma) also known as little western bittercress. Shotweed is a member of the Brassicaceae family. It is generally less than 5 inches tall, with small, round, green leaves and tiny white flowers. The seed pods are thin and one to two inches long. When mature, the pods burst open explosively, thus aptly known as shotweed. Little bittercress is a fall/winter-germinating annual species, native to Europe. Shotweed can be found in recently disturbed areas, roadsides, and cultivated ground. Cardamine hirsuta, hairy bittercress is a close cousin. Both plants are often mistaken for each other.
Your best defense against this insidious weed is to pull early and pull often!
Next on my hit list is English ivy (Hedera helix.) This one is so evil, I am counting it as 2 and 3! English ivy is Public Enemy Number One in Oregon as its sale or import is banned. English ivy is an evergreen climbing plant, growing 50-60 feet in trees, cliffs or walls or as a ground cover where there are no vertical surfaces. Ivy clings to surfaces by aerial rootlets which exude a sticky substance, helping the vines adhere to surfaces.
English ivy leaves are usually a dark green, sporting 3 to 5 lobes. Round, unlobed leaves are found on mature plants in full sun that are ready to flower. The small, pale yellow-green flowers bloom in the fall, with black-purple berries to follow in the winter. Although ivy spreads vegetatively and new plants can root into the ground from the smallest piece of vine, seeds from the berries can also be spread by birds such as the Cedar Waxwing, the Northern Robin, Stellar Jay and others.
English Ivy was first introduced from Europe as an ornamental but it has since become a threat to native plants in the Pacific Northwest. As the ivy climbs up the trees, it encompasses the branches, blocking light from reaching the tree’s leaves. Also, due to the increased weight of the branches, ivy-infested trees are more likely to blow over in heavy wind, rain or snow storms. On the ground, ivy forms dense mats of vegetation, making it difficult for native plants to establish and grow. Although, Ivy prefers woodlands, or other upland areas in slightly acidic moist, soils, the Pacific Northwest summer dry season doesn’t seem to slow it down much.
The best way to rid your garden of this menace is to trim it off of the trees first to kill the upper portions of the vines and then pull all of the rootlets up in the Fall or Winter, when it is using its stored energy to produce berries. You may also need to apply an herbicide to the foliage. Continue to pull up any stray rootlets.
Don’t turn your back on this one – it may eat you or your garden!