Definition of Canada thistle in English:

Canada thistle


North American
  • The European creeping or field thistle, which has become naturalized as a serious weed in North America.

    Cirsium arvense, family Compositae

    • ‘Under growth-chamber conditions, mite populations on a Canada thistle plant can reach very high levels, causing severe damage to the plant.’
    • ‘Fields with quackgrass, Canada thistle, and other cool-season perennial weeds will almost always require the use of glyphosate around the time of planting.’
    • ‘The larvae of the painted lady butterfly - the thistle caterpillar - have been drawing a large amount of attention from anyone who has observed Canada thistle patches this spring.’
    • ‘Tillage with a chisel plow, disk, or field cultivator may actually help spread perennials with creeping root systems, such as Canada thistle and hemp dogbane.’
    • ‘Perennial grasses such as bluegrass and quackgrass and broadleaves such as Canada thistle, bindweed, and curly dock also could be addressed with the weed control program.’
    • ‘In particular, perennial broadleafs and grasses such as dandelion, curly dock, Canada thistle, and quackgrass are much easier to manage prior to planting a forage crop.’
    • ‘Perennials such as Canada thistle, hoary vervain, ironweed, goldenrod, and curly dock generally respond better to fall applications when the plant energy reserves are translocated down to the roots.’
    • ‘Occasionally, broadleaf weeds, such as Canada thistle or ragweed, become established in winter wheat fields and interfere with grain harvest or with the following soybean crop.’
    • ‘As agriculture expanded onto the prairies, wild oats and sow thistle, leafy spurge and Canada thistle migrated westward.’
    • ‘The weeds that appear above the wheat canopy late in the season, such as ragweeds and Canada thistle, can often be easily controlled with a spring herbicide treatment.’
    • ‘A search is under way for viral-infected Canada thistle plants in the areas where they were once reported - Denmark, England, and North Dakota.’
    • ‘Avoid tilling overly aggressive or invasive plants that produce root-buds, such as crabgrass, johnsongrass, bindweed or Canada thistle.’
    • ‘Herbaceous perennials, such as quackgrass, mugwort, and Canada thistle, die back to the ground each year.’
    • ‘Smartweed often grows in potassium-poor soil, while Canada thistle suggests low magnesium levels.’