All About Weeds

Wherever We Go, Weeds Go With Us

Invasive, noxious weeds are the inevitable result of human travel and trade. Wherever we go, it seems, we take seeds and plants with us--sometimes intentionally, sometimes accidentally. And once they arrive, certain plants take advantage of their new location by spreading seeds widely and growing so rampantly that they overwhelm and displace native plants, and invade farm fields, orchards and rangelands. This is not a new problem. As settlers moved west in the 19th century, they inadvertently brought seeds of Canada thistle--a weed farmers and land managers still fight to control over one hundred years later. Today, new introductions of invasive plants--both aquatic and terrestrial--continue. And as climate change looms, we face the potential for new invasions with unpredictable consequences.

Indigobush invasion along a river

How Noxious Weeds Spread

The more people travel, and the more globally connected our world becomes, the more we spread seeds and plant fragments across countries and continents. Plants and seeds hitchhike on wheels, shoes, and cargo. They cling to boats, and spread along rail and road corridors, irrigation ditches, canals and streams. They hide in the folds of tents and backpacking gear. Noxious weed seeds also enter our state as contaminants in birdseed, crop seeds, and wildflower seed mixes.

Invasive plants also escape from our gardens. In fact, about half of the invasive plant species in Washington were brought here as ornamental plants. As new varieties of garden plants are introduced, it is inevitable that new invasive species will continue to escape from gardens across the state. New invasive species add to an already robust population of invasives that have become well established in our state. Canada thistle, Scotch broom, and many other noxious weeds are already far beyond any possibility of eradication, and the best that can be hoped for is to keep them from spreading further, and to limit the damage they do.