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Over 4,600 acres of Western land are being invaded each day.
Whoa! What invasion? Why haven't we heard about this before?
This silent attack is the aggressive destruction of land by invasive, noxious weeds. Well, maybe we've heard about this but it really doesn't affect us. Or, does It? What is a noxious weed anyway?
A noxious weed is a legal term under State and Federal Law for plants with aggressive growth habits that are not native to the U.S. These plants have no natural enemies or diseases to limit their spread. Noxious plants establish quickly in almost any environment, wet or dry, sun or shade. They out-compete native plants for water, sun and nutrients and are difficult to destroy. Non-natives multiply rapidly, eliminating other vegetation as they grow.
All of us are affected and we should all be concerned. The invasive plants have become established in recreational lands, farm and ranch lands, and our backyards. Our environment is threatened by the disappearance and destruction of native vegetation.
Recreation is impacted by the presence of these noxious plants. Thistles crowd banks of rivers and lakes preventing access by hunters, fishermen and wildlife. Noxious plants can interfere with campgrounds, biking trails and activities such as bird watching and photography.
Wetlands are losing the native cattails and the wildlife that is usually present in these areas. Animals are unable to browse the invading plants as they are often unpalatable and sometimes poisonous. The invasives change the predator / prey ratio.
When the noxious plants invade ranch lands and farm lands, they impact grazing and farming. Stock refuse to graze land that is 10% to 20% infested with leafy spurge (Euphorbia esula). A ranch with 80% infestation of this invader is said to have no grazing capacity at all. In many areas, the value of ranch land has plummeted, when invasives are present. Ranchers have sold out for less than 20% of the normal value or returned the land to the lender.
Invasive plants can out-compete planted crops and reduce crop quality. Much time and money is spent trying to eliminate the invasives. Weed contaminants in harvested crops cause a loss of monetary value to the farmer. Weed seeds in crops may prohibit the sale of some crops. The farmer must spend more time in harvesting and receive less in profit. The invasives reduce the value of the farm land.
If we feel that none of this involves us personally, we are wrong. The cost to the farmers and ranchers and food producers must be made up somehow. There are many costs associated with the maintenance of our parks, recreation areas and roadways. These fall back on us as increased cost for food and goods and increased taxes.
In addition, if our yards or properties have dandelions, bindweed, thistle or one of the ornamentals such as dame's rocket (Hesperis matronalis), ox-eye daisy (Chrysanthemum leucanthemum), common St Johnswort (Hypericum perforatum) or any of the some sixty plants on the noxious weed list, we need to be aware. State and Federal Law holds the landowners responsible for control of the noxious plants on their own land and indicates that fines could result if invasives are not controlled.
There are no "Plant Police" to tell us when we have invasive non-native plants on our property. It is up to each of us to eliminate and prevent them from growing on our land. Don't plant them, don't let them flower, don't let them go to seed. Don't let them in. The failure to stop the noxious plants could mean the loss of our biodiversity, ecosystem stability and the balance of nature on which all species depend.
For further information on noxious weeds call the Larimer County Extension
Office at 498-6000 or the Larimer County Weed Control District at 498-5769.
Colorado's Top Ten Noxious Weeds -- prioritized. The list for individual counties may be slightly different.
Canada thistle (Cirsium arvense)
Diffuse knapweed (Centaurea diffuse)
Field bindweed (Convolvulus arvensis)
Hoary cress, Whitetop (Cardaroa draba)
Jointed goatgrass (Aegilops cylindrica)
Leafy spurge (Euphorbia esula)
Musk thistle (Carduus nutans)
Russian knapweed (Centaurea maculosa)
Spatted knapweed (Centaurea maculosa)
Yellow toadflax (Linaria vulgaris)
Q: My tomato plants look very healthy. They have plenty of blossoms but there are hardly any little tomatoes forming. What am I doing wrong?
A: We can blame it on Mother Nature. When daytime temperatures rise above 90 degrees for extended periods of time and the humidity is low, the blossoms drop off. Hormones that help to set fruit do not seem to help in this case. If our daytime temperatures normalize, the plants will resume production. If the temperatures remain high, the resulting tomato crop will be smaller than usual. Make sure the tomatoes receive enough water. Don’t use fertilizer with large amounts of nitrogen as the condition could worsen.
Q: I have a very large rose garden. This year something is eating circular holes in the edges of the leaves. What is causing this and what do I do about it.
A: It sounds like leafcutter bees. They are native bees that look similar to honeybees. They prefer plants in the rose family and can cut these holes in a matter of seconds. They use the pieces of leaves to construct nesting cells for their young. The pieces are rolled into thimble-shaped cells and packed with pollen for the young to develop. The cells are placed into hiding places. These bees do a great deal of pollinating and control is not recommended. The damage is usually superficial and generally does not hurt the plant. If you live in an area where there are large populations of these bees, the plants can be covered with mesh screening as other types of controls have little effect.
If your garden makes you sneeze every summer consider redesigning with low-allergen plants such as; snapdragon, petunia, mealy-cup sage, pansy, delphinium, daylilies, peony, hollyhock, or crabapple. Plants to avoid include; grasses, birch trees, garden mums (and other members of the daisy family such as cosmos, sunflower, zinnia and marigold), asters, cleome, foxglove and lantana, plus strongly scented flowers such as carnations and lavender.
One way to keep your home and garden mosquito free is to create an environment that discourages mosquitoes from breeding on the premises. Mosquitoes like standing water so look for areas around your home that collect water such as, rain barrels, buckets, old tires, or pools that form under water spigots and drain them as soon as possible.
Summers drought is tough on your hanging planters. Give them a boost by placing planter and all in a bucket of water. Add 1 teaspoon of soluble plant food (9-59-9 is recommended for blooming), to one gallon of water and let it soak for 30 – 60 minutes.
The authors have received training through Colorado State University Cooperative Extension's Master Gardener program and is a Master Gardener volunteer for Larimer County.
Fact Sheets are available at the Larimer County Extension Office, 1525 Blue Spruce Drive, Fort Collins, Colorado, telephone (970) 498-6000, or contact us by e-mail at larimer@coop.ext.colostate.edu
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