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April 21, 2014
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Plants behaving badly; Love that ‘ornamental’ plant? Not so fast, please

Mile-a-minute weed is a prickly, branching, annual vine that germinates in early spring, usually in April or May, in the mid-Atlantic region. Vines grow rapidly, climbing over other plants, and attain lengths of six meters or more. Flowers are inconspicuous, and iridescent blueberry-like achenes are produced, beginning in mid-summer and continuing until the plants are killed by frost in the fall.


Myers stresses that river valleys are potential hotbeds for invasive species because they provide conditions ideal for invasive spread. Water, wind, soil, birds, animals and humans all do their part to disseminate seeds, spores and roots. But, Myers says, humans are by far the worst culprits. Not only are they more numerous than other agents, but they also travel farther and faster and cause more environmental disturbance wherever they go. Disturbed soil is the best medium for invasive plants.

Prevention

Prevention is the first line of defense in any management program. Invasive species should not be planted knowingly. Surprisingly, some invaders are available from nurseries—Japanese barberry, purple loosestrife and Japanese honeysuckle among them. To guard against deliberate planting, consumers should be able to identify invaders by both name and appearance; additionally, Myers urges consumers to obtain their plants from native plant providers, plant swaps and nurseries that grow their plants from seeds or cuttings.

Management/Eradication

Methods for management and eradication of invaders vary in accordance with the individual species’ methods of propagation. Options include manual removal (hand weeding), machine removal (mowing, weed whacking), herbicides, grazing (sheep and goats will eat anything edible down to and including roots), burning, and biological attack by natural enemies of the invader (insects, bacteria and fungi). Each method has both advantages and drawbacks, and no one method is safe and effective against all invaders and under all circumstances. There is one more option, to be used either as a last resort and/or a best defense—harvesting. Each plant species, however antisocial its behavior, has attributes that make it useful. Even Japanese knotweed, one of the most tenacious and pervasive invaders, has its uses. The plant’s stalks are used in papermaking. Honey made from its blossoms is considered a delicacy. The plant’s botanical properties are currently being used in the treatment of Lyme Disease. And bakers may find that the plant’s young stalks make a delicious dessert (see Japanese Knotweed Squares recipe).