Enter your email address to subscribe to this blog and receive notifications of new posts by email. These prickles are an adaptation that protects the plant from being eaten by herbivores. That’s up to you, but if you’re serious about invasive plants then you shouldn’t follow them blindly. Seed production is usually completed in early July. “Canada thistle threatens productivity in both crop and non-croplands. Only recently have the harmful impacts of Canada thistle to native species and natural ecosystems received notable attention.”, Idaho: Because he has a lot of links to research in his response, I thought it should have its own posting. In my opinion Canadian thistle isn’t where it’s at. 4. It helps heal land by keeping people and livestock off it, for one thing! Cirsium arvense presents an economic threat to farmers and ranchers. 1993). In non-cropland ecosystems, Canada thistle can crowd out and replace native grasses and forbs limiting land’s recreational use. The aesthetic value of a pasture is also impacted by weeds. “By 1795, Vermont enacted noxious weed legislation against Canada thistle and, in the early 1900’s, the currently named Noxious Weed Act gave a person the right to eradicate this species wherever they found it without fear of trespassing. This highly invasive thistle prevents the coexistence of other plant species through shading, competition for soil resources and possibly through the release of chemical toxins poisonous to other plants. 3. “Noxious weeds are found in range and pasture as well as noncrop areas and cropland. I have to agree with Jeff’s first comment. Most Canada thistle patches spread at a rate of 3-6 feet/year, crowding out more desirable species and creating thistle monocultures. It also invades wet areas with fluctuating water levels such as streambanks, sedge meadows, and wet prairies. Mowing or pulling this weed is not effective because it grows again from vegetative buds on the roots. "The Garden Professors" Facebook page - www.facebook.com/TheGardenProfessors Most of the seeds germinate within a year, but some may remain viable in the soil for up to … Canada thistle or Canadian thistle, featured here, is native to Eurasia, where it is known as creeping thistle, due to its ability to spread via roots into dense patches. “Thistles are pioneer species and are most often found in sites where the ground cover has been disturbed by grazing, erosion, traffic, or other means. Canada thistle, flowers in South Dakota - Photo by Chris Evans; University of Illinois. ), From the Minnesota pdf referenced above: She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. (Of course, the goldfinches would disagree with me!). Canada thistle invades natural communities primarily through vegetative expansion, and secondarily through seedling establishment. Livestock owners hate it and see it only as an invasive plant, especially since few domestic animals will feed on it. Canada thistle (Cirsium arvense) is a root-creeping perennial. Tall thistle has silver color on the underside of its leaves. It actually came from Europe. Because of its contribution to the persistence of the weed, Canada thistle's extensive root system must be the target of an effective control program. “Noxious weeds are difficult to control and injurious to public health, the environment, roads, crops, livestock and property. The plant is beneficial for pollinators that rely on nectar. While Canada thistle (not surprisingly) grows throughout much of Canada, this weed also thrives in most of the U.S., as well as Europe and Asia. Please click hereto see a distribution map of Canada thistle in Washington. Cirsium arvense is a perennial species of flowering plant in the family Asteraceae, native throughout Europe and western Asia, northern Africa and widely introduced elsewhere. In Canada and the U.S., it is considered one of the most tenacious and economically important agricultural weeds, but only in recent years has it been recognized as a problem in natural areas. When thistle starts sprouting in their yards, some determine to never use this feed again. Ray Eckhart, Master Gardener and loyal blog reader, wrote a long response to Alan’s request for research for the ongoing debate on Canada thistle started a few weeks ago by Jeff. It was introduced to North America in the 1600s, probably in agricultural seed shipments and is now widespread throughout the United States and Canada. Tall thistle is generally no taller than musk thistle -- 5 to 7 feet tall. Add livestock and dairy interests, and I think you’re tilting at windmills with your fellows on the committee. Organic Canada Thistle Control. then {{format_dollars}}{{start_price}}{{format_cents}} per month. Most native thistles are either silver or light greenish-gray in color, or have some silver on parts of the plant, he says. And the difference can be confusing, particularly when they look so much alike. aggressive root spread crowds out In Montana, it is estimated that two shoots per square yard can reduce wheat yield by 15 percent and 25 shoots per square yard can reduce wheat yield by 60 percent. Canada Thistle Where Did it Come From? It is also commonly known as Canada thistle and field thistle.. Perennial, wickedly persistent Canada thistle—Cirsium arvense, which is not native, despite its common name. Infestations of Scotch thistle reduce forage production and virtually prohibit land utilization for livestock Heavy infestations are also commonly found in overgrazed pastures and ranges and may crowd-out and replace native grasses and forbs, decreasing species diversity in an area. Canada thistle is a cool season perennial which spreads by seed and vegetatively by creeping roots. This list includes tansy ragwort, yellow starthistle, Russian knapweed, Canada thistle (Cirsium arvense), poison hemlocks, field bindweed, houndstongue, Scotchbroom (Cytisus scoparius), horsetails, leafy spurge, black henbane (Hyoscyamus niger), Klamath weed or St. Johnswort, kochia, yellow toadflax or butter-and-eggs (Linaria vulgaris), silverleaf nightshade (Solanum elaeagnifolium), and puncture vine.”, Colorado: “Canada thistle (Cirsium arvense) is an aggressive, creeping perennial weed that infests crops, pastures, rangeland, roadsides and noncrop areas. Other Montana crops seriously threatened by Canada thistle include peas, corn, beans, alfalfa and sugar beets. Virginia is a prime example in that there are only two weeds listed yet neighboring North Carolina, with very similar climate and growing conditions, lists over a hundred. Of the 11 on the Minnesota list, can you rank them, and tell us why or why not they should be on there? Biology. “Canada thistle is declared a “noxious weed” throughout the U.S. and has long been recognized as a major agricultural pest, costing tens of millions of dollars in direct crop losses annually and additional millions costs for control. At the time I didn't even think to … Should you ignore the lists? Personally, I say destroy every one of the nasty things you see. Not Your Average Thistle The key to Canada thistle's weediness is its root system. Find the base of the Canada thistle plant and simply snip it off at the base. Were I in your position, I’d spend my “Political Capital”, on eliminating all the native, beneficial species on the Minnesota secondary noxious weed list bannable at the county level by petition. In 2002, the Colorado Department of Agriculture surveyed counties and while incomplete, the results showed more than 100,000 acres infested with Canada thistle (Figure 1).”. I make a distinction between noxious and invasive, first off. Bob Rodgers at Survivopedia has an article on Why You Need to Use Thistle for Food and Medicine. The … Wildflowers Of WisconsinWild… Scientific Name: Cirsium arvense (L.) Scop (ITIS) Common Name: Canada thistle, Californian thistle, Canadian thistle, creeping thistle, field thistle, corn thistle, perennial thistle, field thistle. The problem is … Species diversity in an “undisturbed” Colorado grassland was inversely proportional to the relative frequency of Canada thistle (Stachion and Zimdahl 1980). We (the people of this country) only have so much in the way of resources to combat invasive plants and noxious weeds, so we need to do our best to focus our efforts where it really matters. Canada thistle definition, an Old World plant, Cirsium arvense, having small purple or white flower heads, now a troublesome weed in North America. Flowers are pink, bristly, 1/2 inch long and wide. While Canada thistle is the main problem species in this section, there are several other weeds we aim to eliminate such as bindweed, creeping purslane, and pigweed, which have been treated and will be observed as well. They were quiet, pretty, often-mowed places that gave us green and shade in the urban env…. It invades natural areas such as prairies and dunes that have disturbance. We had a pretty bad outbreak of Canada Thistle (which is a deemed noxious weed in Washington state) a few years ago in our garden. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Canada Thistle is also a food source for the engrailed moth. “Ecological: Canada thistle spreads rapidly through horizontal roots, which give rise to shoots (Moore 1975). So Meyer is hoping a little education will help people distinguish between good and bad thistles with pinkish-purple flowers. Canada thistle is a native plant to regions of Europe and Asia but is considered noxious everywhere else. I'm sure its tap root is quite good for loosening and building soil. Thistles reduce the use of an area for grazing or recreational purposes because of the prominent spines on leaves, stalks, and blooms. Once established, it spreads quickly replacing native plants. If the political process is not the way that legal definitions are made, what do you propose as an alternative? (* about $6500 of my annual salary and benefits comes from fulfilling Master Gardener responsibilities. “In the Northeast, several weeds including bull and musk thistle, Canada thistle, purple loosestrife (Lythrum salicaria), mile-a-minute (Polygonum perfoliatum), and garlic mustard (Allaria petifolia) are receiving attention [for biological control efforts – ed.] This year, perhaps because of a wet fall a year ago, tall thistle is abundant, said Meyer. The thistle gained a bad reputation when people interacted with its prickles and when it made its way onto their properties. Canada Thistle is not from Canada. It also increases harvesting problems due to seed and forage contamination. In pastures, Canada thistle reduces productivity by crowding out forage species with spiny leaves that deter cattle from grazing. Others will disagree. On what basis should folks like you be more or less cavalier? Even research can be suspect if, as Jeff points out, the thistle isn’t being compared with other weeds as opposed to pristine growing conditions. Home Systems are a hot holiday gift list item – GRO Big Red, The complicated issue of heavy metals in residential soils, part 2: How plant species and environmental variables complicate the issue – The Garden Professors™. A stem and a basal clump are shown here, left of the glove. You have permission to edit this article. Basically the citations above point out that this stuff is a weed — which we already knew — I just don’t see this information raising Canadian thistle to the level of noxious weed. Canada thistle. Once it’s here efforts to stop them aren’t usually that effective (sometimes biological controls will work). The result is a loss of natural diversity. 2nd Cite for Pennsylvania: It is also known as cursed thistle, probably due to the fact that chopping the roots with a plow effectively spreads the thistle across a field. native to Europe and Asia introduced to Canada as a contaminant of a crop seed in the early 1600s has spread throughout most of the continental United States and Alaska Why is it Bad? The wind-dispersed seeds may remain viable for 20 years or more, allowing it to spread quickly and making it difficult to eradicate.”. Stay up-to-date on the latest in local and national government and political topics with our newsletter. Controlling Canada thistle organically is done with a sharp eye and an even sharper pair of scissors. Email notifications are only sent once a day, and only if there are new matching items. Canada thistle is a creeping perennial that reproduces from vegetative buds in its root system and from seed. It also increases harvesting problems due to seed and forage contamination. It produces nitrate, which can be toxic to your horse if ingested in large quantities. Deer tend to avoid it, though. Tall thistle flowers in August and September in eastern Nebraska. If treated properly and in a timely manner using medication and intravenous … In fact, improper cultivation can even worsen Canada thistle problems!”, From Pennsylvania: She is WSU’s Extension Urban Horticulturist and an Associate Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. How can one differentiate between fact and baseless opinion when no actual research is presented as is the case with the danger stated of thistle to pasture. Tall thistle is often found in drainage ditches and wetland areas and not in pastures. I think you’ll find that the answer is emerging weed problems rather than weeds which have been here for almost 400 years. View all posts by Linda Chalker-Scott. Bull thistles (Cirsium vulgare) are exactly that – bullish. It poses an economic threat to the agriculture industry by reducing crop yields.”, Virginia: Click to share on Facebook (Opens in new window), Click to share on Twitter (Opens in new window), Click to share on Pocket (Opens in new window), The complicated issue of heavy metals in residential soils, part 2: How plant species and environmental variables complicate the issue, The worms crawl in and the worms crawl out but these worms kill your plants, Hydroponics for the Holidays? In cases of the varieties mentioned above, intoxication can be cumulative and lead to a variety of clinical signs. Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). From Montana: I’ll leave cannabis out the discussion, for obvious reasons, but I don’t think it should be “up to me” to decide these things. These unwanted plants are often more aggressive than existing or desired forage species and compete for light, water, and nutrients. And although I greatly value your opinion, my skepticism dictates more facts and figures before I’d sign a petition to remove canada thistle from the noxious weed list. It stores food energy in its extensive root system both to survive the winter and to fuel the plant's reproductive drive the following season. Characteristics of Canada thistle are extremely variable when examining populations from different regions. Canada thistle is an aggressively spreading perennial weed that has deep, creeping roots which make it difficult and time-consuming to remove. In some cases it may lead to cuts and sometimes infections — but it’s not toxic. Canada thistle (Cirsium arvense) is a persistent perennial weed that causes significant crop yield losses. In cropland, Canada thistle causes extensive yield losses through competition for light, nutrients, and moisture. But why is it so tough to get rid of Canada thistle and what is the best way to do so? Both natural and human caused disturbances can create the opportunity for Canada thistle to become established in natural communities.”, Ohio: Biennial thistles spread only by seed (achenes) that are produced in great number by all the noxious species, ra… Ask yourself what weeds you can target where it will make the most difference. One reference points out that Canadian thistle is toxic to horses — that’s wrong. Canada thistle is common in pastures and croplands. Additionally, plants can spread by growing in circular … But it is more of a bushy plant. Get up-to-the-minute news sent straight to your device. This time of the year the blooming plant is likely tall thistle, a good thistle, a native thistle. Considered noxious under the BC Weed Control Act, Canada thistle is commonly found on roadsides, cultivated fields, pastures, logged forests, riverbanks, and other disturbed areas. In general, thistle consumption isn’t ideal. Native To: Europe . Spreading both by seed and rhizome, Canada thistle can create monocultures covering large areas. Canada thistle — which is actually not native to North America — is a perennial, so it is harder to control. Books: http://www.sustainablelandscapesandgardens.com Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. An Oligarchcal Committee of Horticulturists unswayed and uswayable by political interests? Note the running roots, which can persist and keep sprouting even through a year or two of frequent pulling or spraying with herbicide. It also invades wet areas with fluctuating water levels such as stream banks, sedge meadows and wet prairies.