Remove those noxious weeds
By Tim D'Amato
Larimer County Department of Natural Resources
Back to Gardening Articles List
For those who enjoy learning new oxymorons, here's one for you--ornamental
weeds. The term describes noxious weed species that originated as garden
plants, then jumped fences to invade forests, river systems, wetlands,
pastures, rangeland and roadsides.
Many of the weed problems confronting Colorado land managers originated
from backyard flower gardens. How did this come about? Over the course
of decades, the plant nursery industry has selected ornamental plants from
all over the world for various characteristics. A showy, attractive flower
obviously tops the list, but other characteristics desirable in the western
United States are drought tolerance, soil stabilization and food and cover
for wildlife. In most cases this has not been a problem. Landowners are
encouraged to plant xeric species to reduce water needs, and to provide
food and cover for wildlife.
Unfortunately many of the ornamental plants introduced from other parts
of the world have adapted too well. Without environmental checks from native
lands such as predatory insects, soil nematodes, disease and other factors,
some plant species have become invasive and detrimental to our natural
areas. A few examples are:
Yellow toadflax, better known as butter-and-eggs. This perennial of the
snapdragon family has invaded many natural areas near mountain communities.
In the Flat Tops Wilderness near Meeker, yellow toadflax is a major weed
infesting thousands of acres.
Purple loosestrife, a perennial plant that thrives in riparian areas
displacing native plants and wildlife. Purple loosestrife dominates millions
of acres of marshland in Eastern and Midwestern states, but in Colorado,
it is uncommon enough that diligent management efforts could eventually
result in eradication.
Russian olive, a thorny tree that readily spreads by seed. Russian olives
were at one time promoted for windbreaks by government agencies and were
widely planted as ornamental trees. Many river bottoms and other moist
sites are now dominated by dense thickets of Russian olives.
These plants and others determined to be invasive are now on the prohibited
sales list for plant nurseries in Colorado. Many ornamental plants are
on the State Noxious Weed list categorized as List A species that require
eradication: myrtle spurge, cypress spurge, dyer's woad, orange hawkweed
and purple loosestrife. Others categorized as List B species may require
management depending on local weed ordinances: absinth wormwood, bouncingbet,
chamomile, Chinese clematis, dalmatian toadflax, dames rocket, oxeye daisy,
Russian olive, saltcedar and yellow toadflax.
Be a responsible gardener and remove any of these species if you have them
on your property. For further information contact the Larimer County Weed
District office at 498-5768 or Colorado State University Extension office
at 498-6003.
Tim D'Amato is the land stewardship manager for the Larimer County Department
of Natural Resources.
|
