A plan for attack on alien plants

Coming to a yard near you ... plants that can blister your skin with their milky sap, grab onto your car’s undercarriage, and even use human clothing for transportation.

Don’t bother trying to run. Some of these plants can produce more than a million seeds in one summer and they’ll just keep spreading.

Although this might sound like a science-fiction movie plot, this is the all-too-true world of noxious weeds.

These alien plants take over, crowding out native vegetation with their remarkably effective survival methods. With thorns and prickles they thwart picking, with hooks and barbs they hitch rides to new habitat, and with long, stubborn taproots they guzzle water. These invasive weeds have adapted too well to our high-desert climate. Ironically, some were brought here on purpose to provide fast-growing shade, prevent erosion or just look pretty.

Early spring is prime time for developing your plan of attack on weeds. If you’re going to have a chance against their tricks, your first step is to find out as much as you can about your opponents and their weaknesses before they spread.

Melissa Werkmeister, Mesa County’s weed and pest coordinator, said the first step is identifying the weed. If you don’t know what it is, she suggests bringing a sample of the unknown weed to the Colorado State University Extension office. After you know what you’re dealing with, it’s easier to formulate your strategy to control or eradicate the weed.

So, what is a weed, anyway? Some people might just say it’s any unwanted plant growing where you don’t want it to be.

The state of Colorado actually maintains a carefully selected list of noxious weeds, and state law requires plans to eradicate, control or monitor those weeds.

You might be surprised to see which types of weeds made the official state hit list. Some of the most well-known weeds, such as dandelions, don’t make the list, which is separated into a tier of priorities with the A, B and C lists.

A-List weeds are the most-wanted weeds. They’re generally rare in Colorado, and officials have a priority of eradicating them as soon as they’re noticed. They are usually big problems in other states and the idea is to get rid of them completely. The Colorado Department of Agriculture gives grants to counties to help fund eradication projects for those weeds.

B-List weeds are more common, and may require eradication in some counties but not others. Some of these plants are purposely planted as part of landscapes — the most common ones around here being the Russian olive and the tamarisk (salt cedar).

C-List weeds are widespread across Colorado, and are probably the ones most people know, such as bindweed and puncturevine (goats head).

There’s also an official “watch list” weed-management specialists are keeping an eye on to make sure they don’t take over.

I admit, I have one of these in my yard: baby’s breath. Another one on the list common to many landscapes is pampas grass.

One of the A-List weeds that Werkmeister has fought in Mesa County is purple loosestrife. The weed is actually quite pretty, so pretty that people have asked Werkmeister where they could get one for their yards (Her answer: Um, no). It’s so invasive and stubborn that once it gets established, it’s very labor-intensive to eradicate.

Purple loosestrife grows up to 10 feet tall and thrives in wet areas such as drainage ditches and washes. Last summer, Werkmeister and her work crews spent 32 days clearing the persistent weed, slogging through mucky water to cut down the tall tops and bag the seed heads, and spraying the remaining plants.

“We had 80 trash bags of it we had to get rid of last year,” she said. “And that’s just one weed.”

Even B-List weeds can be downright dangerous. For example, Russian knapweed is poisonous to horses and causes a neurological disorder that makes it impossible for the horse to chew and eventually the animal starves.

Russian knapweed also produces alleopathic chemicals, meaning it secretes a substance into the surrounding soil that discourages other plants from growing. This reduces competition for resources and allows the weed to invade undisturbed areas. Even in dry years, Russian knapweed might appear to go away, but it’s always lurking underground.

“They have roots that can go 5 to 10 feet deep,” Werkmeister said. “They’re really naughty, because you spray them and you think they might be dead, and then they just send out a root and come up in another place.”

Another B-Lister, leafy spurge, can rocket its seeds up to 15 feet away from the mother plant and contains noxious sap that causes blisters in the mouths of animals unlucky enough to eat it. This sap can also cause serious skin reactions for people who pull it bare-handed.

Whether you have state-mandated noxious weeds on your property or just weeds on your personal hit list, Werkmeister has suggestions that will save you time, money and effort in winning the war on weeds. One of the most popular misconceptions about killing weeds is that one herbicide will work on everything.

“Some people think glyphosate is a miracle chemical and they can use it for everything,” she said, referring to the active ingredient in Round-Up. “And some people think if you use a little bit of a chemical, then a lot more is better.”

The reality is, “You need to use the right method at the right time, for the right plant,” said Werkmeister. One herbicide may prove more effective than others.

And there might be some tricks about spraying a certain weed after it produces buds but before it blooms. The wrong herbicide might kill the top of the plant, but not the root, so it’s a waste of time trying to kill it repeatedly.

Don’t be drawn in by fancy weed-killer names like “Killz- All, “Mad Dog,” or “Shotgun.” You need to know which active ingredient will kill the weed you are fighting, Werkmeister said.

“People get this gleam in their eye when they tell you what they used, because it sounds like it’s going to do what you want,” she said. “But you want to be using the right herbicide for the job.”

For information, go to http://www.mesacounty.us/pest, or http://www.cwma.org. You also can contact the CSU Extension master gardeners at 244-1836 or bring a sample of your weed to their office, located next to the Mesa County Fairgrounds.

Erin McIntyre is a writer, master gardener and owner of the gourmet pickle company, Yum Pickles. Email her at .(JavaScript must be enabled to view this email address).


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