What? No dyer’s woad?
The most surprising part of polling local experts about Northern Utah’s most noxious weeds is not what’s on the list, but what’s not on it. While plants like yellow starthistle, purple loosestrife and puncturevine easily made the weed police’s most wanted — or unwanted — list, dyer’s woad was nowhere to be found.
Nor was the bane of the homeowner’s existence, the common dandelion.
Joe Hadley, Weber County weed supervisor, says dyer’s woad doesn’t make his list of most notorious weeds because “I almost don’t like to think about it.” He calls Isatis tinctoria the “problem child” of weeds — an infestation so bad it’s like an out-of-control wildfire.
“I think these other weed problems are small enough we can do something about it, but dyer’s woad is out of control,” Hadley said. “We can try to control it, but we can’t get rid of it.”
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As for dandelions? Ron Patterson, agriculture agent for Utah State University’s Extension Service in Weber County, says they can give gardeners fits, but they simply don’t fit the government definition of “noxious.” That is, any plant that the state commissioner of agriculture and food “determines to be especially injurious to public health, crops, livestock, land or other property.”
Currently, there are more than 50 noxious weeds recognized in the state. And here’s the short list of the ones keeping local weed-control experts up nights.
The Utah Division of Wildlife Resources website calls this 15-foot-tall perennial reed “a serious concern in many Utah wetlands,” with dense stands crowding out more desirable plants. Phragmites australis is found along waterways and ditch banks throughout Utah, according to Hadley, and it causes problems plugging up storm drains.
“And it’s a real fire issue for late fall when it starts to die off,” Hadley said.
Patterson said while there are native phragmites in Utah, they don’t grow as densely as the aggressive, non-native version that has colonized North America.
“And here along the Wasatch Front, most of the native phragmites are gone,” Patterson said.
DWR has been implementing a phragmites control plan along the eastern shore of the Great Salt Lake that involves spraying the weeds with herbicides and then burning them.
2. Yellow starthistle
This noxious weed — scientific name Centaurea solstitialis — looks a bit like an angry dandelion. The 2- to 3-foot-tall winter annual, introduced from Europe, has yellow flowers with cream-colored thorns protruding from them. The plant’s seed head uses these spiny thorns to attach to passing animals, clothing or tires, according to information from Utah State University’s invasive weeds page.
The Utah Weed Control Association says yellow starthistle was introduced from Europe and grows well on dry sites in rangeland, roadsides and waste areas.
Hadley says this weed will overrun an area and not allow other plants to grow there.
“In the years I’ve been doing this, I’ve seen it really multiply,” Hadley said. “It grows along trails and takes over. And you can’t walk through it because it’s mean, with very big thorns.”
If you’ve ridden a bicycle in this state, chances are you’ve had a flat tire or two courtesy of Tribulus terrestris. Often called goat’s head, this annual is native to southern Europe.
The Utah Weed Control Association describes puncturevine as having small yellow flowers that bloom in late spring and early summer. These flowers produce hard, spiny fruits that eventually break into seed pods. These pods are like oddly shaped thumbtacks that lie in wait for unsuspecting bare feet and inflatable objects.
“I’m a biker myself, and I also go barefoot,” she said. “If you’ve ever stepped on a Lego, it’s 10 times worse. And, they pop my bike tires.”
“Pets, bikers, hikers — all kinds of things suffer from those thorns,” added Rod Kramer, outreach coordinator for Weber Pathways.
Kramer says the parking area at Port Ramp Marina, at Pineview Reservoir, was carpeted in puncturevine before a concerted effort was made to eradicate the noxious weed there. It’s an example of a successful weed-eradication program; Kramer says the efforts really made a difference.
“And the reason that’s important is they park 400 cars in there, and every one of those tires is covered in goatheads,” he said. “And then those cars drive all over the county, and you’ve got this amazing seeding program.”
Although Patterson says puncturevine isn’t particularly difficult to control, it continues to germinates throughout the entire summer.
“That’s the reason it’s so hard to keep on top of it,” he said.
It’s not so much that puncturevine crowds out native plants as it takes over barren areas, according to Patterson.
“It doesn’t compete really well,” he said. “If you have plants, pasture or lawn, it doesn’t compete well unless you start overgrazing or don’t water properly.
Patterson says puncturevine is particularly troublesome in areas where the soil has been disturbed, such as along trails and roads.
4. Purple loosestrife
Lythrum salicaria is a 6- to 8-foot-tall semi-aquatic perennial. It often grows along ditch banks and waterways, crowding out native plants and taking over habitat for ducks and other waterfowl, according to Hadley.
This interloper was probably first introduced to the United States as an ornamental plant for gardens, according to information from the Utah Weed Control Association. The offending plant blooms in midsummer, with pinkish-purple flowers appearing in columns along the upper end of its stems.
“It is beautiful, but …” Hadley said, trailing off. “It’s overpowering. It’s too much of a good thing.”
According to DWR, in the past purple loosestrife has been destroyed by hand or using chemicals, but recently biologists have had some success controlling it with insects from its native Europe and Asia that feed on the plant.
5. Russian olive
Elaeagnus angustifolia isn’t a big problem in Northern Utah, but it certainly has the potential to be. The perennial shrub or tree — which grows between 12 and 45 feet tall — can add up to 6 feet in height per year, according to the Utah State University Extension Service’s “Range Plants of Utah” webpage.
The USU page says Russian olive can choke irrigation ditches and crowd out native riparian vegetation, adding: “Once established Russian olive is difficult to control and nearly impossible to eradicate.”
Before taking his position with the Weber County Extension Service, Patterson held a similar job in Carbon and Emery counties, where the Russian olive is overrunning the riparian areas there. He’s quite familiar with the noxious plant, and has done quite a bit of research on it.
“The thing is, it’s not a big problem here yet,” Patterson said. “But if we wait, it can be.”
One of the difficulties, according to Patterson, is that when one Russian olive is removed, dozens of others usually spring up in its place.
“When you tear out a Russian olive tree, in essence you’re inviting 100 pissed off Russian olive tree relatives to the funeral,” he said. “In the south (of the state) it’s a problem. Let’s not let it become a serious problem here.”