Books: http://www.sustainablelandscapesandgardens.com 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. When I started feeding thistle to the birds, I heard somewhere that it will not germinate. {{start_at_rate}} {{format_dollars}} {{start_price}} {{format_cents}} {{term}}, {{promotional_format_dollars}}{{promotional_price}}{{promotional_format_cents}} {{term}}, Outgoing AG Barr: 'No reason' for special counsel on election fraud, Biden's son, How to tell the evil weeds from the merely annoying, Sarah Browning: Fall is best time to control tough weeds, Sarah Browning: Choosing a good tree and getting it started, Here's how Lincoln plans to add beauty and butterflies to city parks, WATCH: City news conference on coronavirus restrictions in Lincoln, Mayor Beutler gives parting thoughts to Lincoln community, Council candidate Stock recalls memorable campaign moment, Council candidate Meginnis recalls memorable campaign moment. Canada thistle is a native plant to regions of Europe and Asia but is considered noxious everywhere else. Canada thistle (Cirsium arvense) is a root-creeping perennial. I’ll leave it to others more qualified than I am to further debate the relative merits of why or why not a more cavalier (heh!) It was introduced to North America in the 1600s, probably in agricultural seed shipments and is now widespread throughout the United States and Canada. Sorry, Jeff. As it establishes itself in an area, Canada thistle crowds out and replaces native plants, changes the structure and species composition of natural plant communities and reduces plant and animal diversity. Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). It also increases harvesting problems due to seed and forage contamination. You have permission to edit this article. “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. 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. It is difficult to control because its extensive root system allows it to recover from control attempts. Musk thistle flowers in May and June in the eastern part of the state. Grazing animals will not eat anywhere near where Canada Thistle grows, so if you own horses or cows, a bad infestation of Canada Thistle in your pastures can cause problems. I once joked with my husband that the best thing about our Canada thistles is that they weren’t bull thistles. Generally these good thistles attract butterflies, sometimes bees, and their seeds are eaten by songbirds. Canada thistle produces an abundance of bristly-plumed seeds which are easily dispersed by the wind. 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. Michael Bociurkiw writes that as the US has struggled to flatten the curve on the coronavirus pandemic, its neighbor to the north -- Canada -- has successfully managed to slow the spread of Covid-19. In Canada, the major impact of Cirsium arvense is in agricultural land, and in natural areas that have been disturbed or are undergoing restoration (White et al. Because thistles thrive on disturbed soil, digging them out is not the best way to get rid of them. 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. As an analogy, You can call yourself a race car driver, but that doesn’t make you one, and I wouldn’t believe you are one without some kind of proof — like an article showing how well you’d done in a race last week. “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.] Can we ignore these lists, based on what you say here? Deer tend to avoid it, though. 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. Seed production is usually completed in early July. Canada thistle, flowers in South Dakota - Photo by Chris Evans; University of Illinois. 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. Hand-pulling and cultivation are often ineffective control mechanisms because new plants sprout from root pieces that snap off. 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. Why is Canada thistle so tenacious? Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). 2. They were quiet, pretty, often-mowed places that gave us green and shade in the urban env…. Canada thistle is a cool season perennial which spreads by seed and vegetatively by creeping roots. Tall thistle is generally no taller than musk thistle -- 5 to 7 feet tall. It was a look-alike relative -- the innocuous tall thistle -- which is a friend to bumblebees and long-horned bees and butterflies, said Superintendent Brent Meyer. 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. How Did it Get Here? There are the bad thistles -- the musk thistle, the plumeless thistle and the Canada thistle, all with purplish flowers -- which came from other countries without their natural predators to … The result is a loss of natural diversity. If the political process is not the way that legal definitions are made, what do you propose as an alternative? 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. 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. 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? These have been designated as noxious weeds, which landowners are required to control. It also invades wet areas with fluctuating water levels such as streambanks, sedge meadows, and wet prairies. Please click hereto see a distribution map of Canada thistle in Washington. 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).”. They are a noxious weed. 2nd cite Colorado: because of their invasive nature.”. Canada thistle is an aggressively spreading perennial weed that has deep, creeping roots which make it difficult and time-consuming to remove. Canada thistle (Cirsium arvense) is a persistent perennial weed that causes significant crop yield losses. Enter your email address to subscribe to this blog and receive notifications of new posts by email. Perennial, wickedly persistent Canada thistle—Cirsium arvense, which is not native, despite its common name. An Oligarchcal Committee of Horticulturists unswayed and uswayable by political interests? This is an interesting discussion but I’m very confused. Most native thistles are either silver or light greenish-gray in color, or have some silver on parts of the plant, he says. (When we first moved here, the place was overrun with thistles. Troublesome statewide noxious weeds like Canada thistle, leafy spurge, perennial sow thistle, Russian knapweed, and hoary cress can be serious problems in pasture and rangeland.”. “Noxious weeds are difficult to control and injurious to public health, the environment, roads, crops, livestock and property. Plants primarily regrow and spread from rhizomes, but infestations can also start from seed. One morning this month the county’s weed superintendent got a call from a golfer who said he'd spotted musk thistle, the noxious weed with the pinkish purple flower, near the sixth fairway at HiMark Golf Course. About half the calls to Meyer’s office this month are from people reporting stands of musk thistle, a noxious weed. which damages corn (Detmers 1927). As mentioned earlier, they thrive in disturbed soils.) And that means many phone calls and people upset because they believe the county weed authority, the local natural resources district and the parks department aren’t doing their job. It also invades wet areas with fluctuating water levels such as stream banks, sedge meadows and wet prairies. Canada thistle is diecious, which means male and female flowers occur on separate plants. ECOLOGICAL THREAT: Natural communities that are threatened by Canada thistle include non-forested plant communities such as prairies, barrens, savannas, glades, sand dunes, fields and meadows that have been impacted by disturbance. This may be partially due to the extensive taproot in many broadleaf weeds that allow them to remain green longer into the dry season, thereby appearing potentially attractive to horses grazing in poor pastures. Only recently have the harmful impacts of Canada thistle to native species and natural ecosystems received notable attention.”, Idaho: Flowers are pink, bristly, 1/2 inch long and wide. See more. We need a comparison to rate the relative harm of CT. At this time of year perennial weeds begin moving carbohydrates f…, Fall’s cooler temperatures, increased moisture and reduced humidity allow properly planted trees to establish their root systems quickly, givi…, For decades, Lincoln city parks were turf and trees. 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. In non-cropland ecosystems, Canada thistle can crowd out and replace native grasses and forbs limiting land’s recreational use. A Monarch butterfly feeds on a native tall thistle. Of the 11 on the Minnesota list, can you rank them, and tell us why or why not they should be on there? It also increases harvesting problems due to seed and forage contamination. “Some noxious or invasive weeds are highly toxic to equines, however, and can cause tremendous problems if allowed to invade horse pastures. Personally, I say destroy every one of the nasty things you see. This isn’t intended to be a defense of Canadian thistle- only a statement of a desire for a more scientific evaluation. 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. Additionally, plants can spread by growing in circular … In cases of the varieties mentioned above, intoxication can be cumulative and lead to a variety of clinical signs. Canada thistle is native to Europe. Livestock do not eat thistles and will not graze between thistle plants on more desirable forage (Batra 1982).”, Invasive.org (linked from .gov sites): When thistle starts sprouting in their yards, some determine to never use this feed again. 4. From Montana: The thistle gained a bad reputation when people interacted with its prickles and when it made its way onto their properties. The reference from Montana points out that two thistles per square yard can have a significant effect on the growth of crops — I certainly believe that, but then many other weeds will do the same thing so I don’t see why that information should make this weed significantly worse than others. 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. then {{format_dollars}}{{start_price}}{{format_cents}} per month. You can cancel at any time. A combination of mowing and herbicides is best, Eckberg said. 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. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. If Dr. Chalker-Scott can use noxious weed lists as a standard against which to judge permaculture practices, on what basis should folks like me be more or less cavalier about them? But why is it so tough to get rid of Canada thistle and what is the best way to do so? Do not pull Canada thistle out, as this can split the root, which causes two Canada thistles to grow back. Canada Thistle Where Did it Come From? 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. In pastures, Canada thistle reduces productivity by crowding out forage species with spiny leaves that deter cattle from grazing. Canada Thistle is also a food source for the engrailed moth. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. 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. There are more, but I stopped on page 3 of the 120 page result of the google .edu search. Biennial thistles, such as musk (Carduus nutans L.), plumeless (Carduus acanthoides L.) and bull thistle [Cirsium vulgare (Savi) Tenore], are not as difficult to control as the perennial thistle species, but spread rapidly and can become severe problems in some areas. Characteristics of Canada thistle are extremely variable when examining populations from different regions. Tall thistle is often found in drainage ditches and wetland areas and not in pastures. “Edibility” thus becomes a non-factor, since it ignores the obvious “You can led a horse to thistle, but you can’t make him eat” factor, and the converse of a fine forage food (and erosion control conservation benefits) in the case of kudzu doesn’t change its undesirability. Hydroponics for the Holidays? “Human: Spiny thickets of Canada thistle can restrict recreational access to infested areas.”, South Dakota: In Minnesota we do have a process by which weeds are listed — and it as objective a process as I’ve seen for these weeds (it is a bit oligarchical at that!). Field bindweed has also been around since colonial times. The wind-dispersed seeds may remain viable for 20 years or more, allowing it to spread quickly and making it difficult to eradicate.”. It grows in circular patches, spreading vegetatively through roots which can spread 10 -12′ in one season. It’s commonly accepted that the time to stop a weed is when it first appears. Livestock owners hate it and see it only as an invasive plant, especially since few domestic animals will feed on it. Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. “THREATS POSED BY THIS SPECIES: Natural areas invaded by Cirsium arvense include prairies and other grasslands in the midwest and Great Plains and riparian areas in the intermountain west. Not Your Average Thistle The key to Canada thistle's weediness is its root system. On what basis should folks like you be more or less cavalier? In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. View all posts by Linda Chalker-Scott. Canada thistle is a perennial plant with an extensive horizontal and vertical rhizome and root system, which can spread 15′ wide and 6-15′ deep. There was a problem saving your notification. In fact, improper cultivation can even worsen Canada thistle problems!”, From Pennsylvania: 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. At the time I didn't even think to … In addition to reducing forage and pasture production, Canada thistle may scratch grazing animals, resulting in small infections (Moore 1975).”, Washington State: In the U.S., it is a host for bean aphid and stalk borer, insects that affect corn and tomatoes (Moore 1975), and for sod-web worm (Crampus sp.) 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™. So Meyer is hoping a little education will help people distinguish between good and bad thistles with pinkish-purple flowers. In my opinion Canadian thistle isn’t where it’s at. These prickles are an adaptation that protects the plant from being eaten by herbivores. The standard English name in its native area is creeping thistle. Canada thistle — which is actually not native to North America — is a perennial, so it is harder to control. In Indiana, Canada thistle normally initiates growth in spring, reaches the flower-bud stage the first week in June, and full flower about the third week of June. The … In some cases it may lead to cuts and sometimes infections — but it’s not toxic. Thistles reduce the use of an area for grazing or recreational purposes because of the prominent spines on leaves, stalks, and blooms. I have to agree with Jeff’s first comment. In cropland, Canada thistle causes extensive yield losses through competition for light, nutrients, and moisture. That said, Canadian thistle is listed because of political pressure (I do sit on the Minnesota Department of Agriculture’s committee which reviews these weeds). By law, these weeds must be controlled on all public and private lands.”. Generally, infestations start on disturbed ground, including ditch banks, overgrazed pastures, tilled fields or abandoned sites. It invades natural areas such as prairies and dunes that have disturbance. Symptoms of toxicity can range from weakness to convulsions and should be considered a serious medical condition. In gardens, flower beds, and lawns, Canada thistle’s extensive root system makes it a hassle to control. 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. 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