Canada thistle is a non-native perennial forb that reproduces/spreads from seed and rhizomes. Canada thistle can reproduce by seed and has male and female flowers on separate plants. It is considered “noxious” in 43 states and is found on every continent except Antarctica. Herbaceous perennial, 2-6.5’ tall with upright, grooved stems that branch near the top of the plant. Planting date: Most likely will not affect Canada thistle infestations. A map showing the distribution of Canada thistle in Iowa in 1898 indicated isolated infestations in only 25 counties. Flower Seed Head. Weeds of Canada and the Northern United States. Production Range: Seed production ranges from 1,500 to 5,300 seeds per plant. FGIS 9180.18 - Special Quality Factor Information for Wheat and Malting Barley Shipments to the European Union (pdf) 04/21/2003 FMD-PPMAB Fields with extensive seed germination should be retilled or treated with herbicide within 40 days ater the seeds germinate to prevent deep root development. Canada thistle, a perennial broadleaf plant, is found in most of the western states except for southern Sierra Nevada, the Sonoran and Mojave deserts, and the Channel Islands. Frequently tilling may also reduce populations if continued for a few years. When buried at greater depths (7-inches or more) and left undisturbed seeds have been found to be viable for up to 30 years. Two years before confederation, legislation required farmers to cut the weed 1. Seed production averages 1,500 seeds per plant, but these remain viable for only a few years (Ministry of Agriculture, Food, and Fisheries 2002Footnote 5). Canada thistle can produce up to 1,500 seeds per flowering shoot. Introduced into the United States around 1750. Canada thistle inhabits … The biology of Canadian weeds. a seed-head fly found in Canada and the United States) can be responsible for 20 to 80% seed predation. This information is for educational purposes only. The seeds of this broadleaf perennial can go dormant for up to 20 years 2, but only about 10% of Canada thistle is spread through seed 1. Canada thistle (Cirsium arvense) is a persistent perennial weed that causes signiﬁcant crop yield losses. Canada thistle (Cirsium arvense (L.) Scop.). If you bring hay on-farm, use a reliable source. Mode(s) of Reproduction: Most local reproduction is from creeping roots. Larvae develop in the flower head and consume the seed as it develops. Sequential herbicide applications may be necessary for control. Dormancy: Though most seed is capable of germinating upon dispersal in the fall it enters secondary dormancy during the winter months. Cultivated fields, old fields, gardens, lawns, pastures, fence lines, shores, thickets, open forests, roadsides, railway lines and other disturbed areas (Darbyshire 2003Footnote 3). Other agents have been studied, but eliminated for various reasons. Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Please refer to E-434, "MSU Weed Control Guide for Field Crops," for herbicide recommendations. Seeds mature rapidly and are able to germinate within eight to 10 days after pollination. This could include tillage, patch mowing, in-crop herbicides, and pre-harvest and post- harvest herbicides. Infests crops including wheat, corn, peas, beans, sugar beets and potatoes, as well as pastures and rangelands (Moore 1975Footnote 4). VASCAN, the database vascular plants of Canada, http://data.canadensys.net/vascan/ [2016, May 30]. Canada thistle requires a multi-year, integrated control strategy. Cirsium arvense (L.) Scop. Introduced to North America, Argentina, Chile, Iceland, Greenland, South Africa, Australia and New Zealand (USDA-ARS 2016Footnote 2). Flowering occurs late spring into summer in response to 14-hour days and are pink to purple in color. It also produces deep creeping rhizomes that allow it to survive below normal tillage depths (Royer and Dickinson 1999Footnote 6). 2002. Application timing and effectiveness: Most susceptible to herbicides between the bud and flower stages of Canada thistle. It it also different from other native North American species given its large roots and … Crop rotation: Canada thistle populations have been shown to be reduced by the use of a summer annual cover crop such as sudangrass (See the cover crop chapter in IWM: Fine Tuning the System). Roots are abundant, deep and creeping, forming a dense patch much the same as bindweed. Department of Plant, Soil and Microbial Sciences. 13. The University of Alberta Press/Lone Pine Publishing, Edmonton, Alberta. A dense patch of thistle may need to be grazed more than once during the summer to prevent seed set. 2016Footnote 1). Don't let it get established! Avoid crops with poor competitive ability and no in-crop herbicide options (e.g., lentils, field peas). Seed may be transported by water, animals, farm equipment and other vehicles, and in contaminated crop seed. Some livestock have been known to graze on Canada thistle at different life stages (see Chapter 5). Nodding thistle achenes have a smooth, varnish-like surface with transverse markings, while the achenes of Canada thistle are fibrous and woody with thin furrows and no transverse lines. Canada thistle plants can also produce a lot of seed that can be distributed long distances by wind, water, and animals. Royer, F. and Dickinson, R. 1999. Consequently, individual plants (and in some instances entire patches) may be seedless. Inventory of Canadian Agricultural Weeds. However, seeds have been found to germinate from 3-inch soil depths. Jeffrey W. Dwyer, Director, MSU Extension, East Lansing, MI 48824. C. thistle invading a disturbed area from perennial rootstocks. Moore, R. J. NebGuide: Canada thistle (CIAR4) OK-OSU Extension-Thistles and their Identification (CIAR4) Ohio State University: Identifying noxious weeds (CIAR4) Purdue University: Control practices for Canada thistle (CIAR4) The Nature Conservancy: Wildland Weeds Management & Research Program (CIAR4) UC Davis, IPM: abstract & images (CIAR4) It differs from other species in the same genus given its dioecious flowers. Plants are either male or female (dioecious) so cross pollination is necessary for seed production. Prefers perennial and no-till cropping systems and rangelands. Not Your Average Thistle The key to Canada thistle's weediness is its root system. Canada thistle spreads both by seeds and by budding from underground roots. 2003. 2. Its deep roots are the real issue. 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. So, if you disturb the soil and break the rhizomes into pieces, they simply develop into new plants. Moderate shoot densities have been shown to reduce spring wheat yield and alfalfa seed yield by up to 50%. Agriculture and Agri-Food Canada, Research Branch. Nodding thistle achenes have a similar size, shape and colour as Canada thistle. Control Canada thistle in roadsides, field roads, and fencerows. Seeds are dark brown and only 1/8 inch long. For interest's sake, I found some Canada Thistle seed and placed it alongside Nyjer. Persistence is imperative so the weed is continually stressed, forcing it to exhaust root nutrient stores and eventually die.Canada thistle (Cir… MSU is an affirmative-action, equal-opportunity employer, committed to achieving excellence through a diverse workforce and inclusive culture that encourages all people to reach their full potential. The top peg is thicker and wider in nodding thistle. Physical description Canada thistle is a perennial that spreads by seed and an underground system of vertical and horizontal roots. FGIS 9180.17 - Inspection of Export Wheat Lots for Canadian Thistle Seed (pdf) 01/04/2011 FMD-PPMAB. Specific Controls Plants can spread vegetatively and over long distances by its seed. Primary Noxious, Class 2 in the Canadian Weed Seeds Order, 2016 under the Seeds Act. Canada Thistle produces flowers from about June until August. Repeated tillage at 7 to 28 day intervals for up to 4 years can be effective on infestations of Canada thistle.