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GREATjU RIVERlRIPW GREENING If burdock has already gone to seed, clip and bag the seed heads to prevent seed dispersal. Prescribed fire can kill young burdock and top kill older plants if there is sufficient fuel to carry a burn. Chemical Apply 2,4-D, glyphosate, or triclopyr as a foliar application to the first year rosette. Foliar herbicide treatment may only top -kill the plant, Follow-up treatment may be required. Alternatively, cut the plant below the basal leaves and stump treat the tap root with glyphosate before the bud stage. Long -Term Management In fire adapted plant communities, prescribed burns can alter the conditions of the site to favor the establishment of native species that can compete with burdock. Fire will also accelerate removal of nutrients including nitrogen which favors burdock. Common Burdock April May June July Aug Sept Oct Nov Dec - Mar Burn Foliar Herbicide Cut Stem Herbicide Mow Flowering Canada Thistle (Cirsium arvense) Description This Eurasian member of the Aster Family was introduced to North America in the early 1600s, and is now one of the most tenacious and economically important agricultural weeds. It is listed as a noxious weed in 43 states. This perennial has an extensive root system with horizontal roots extending 15 feet or more and vertical roots which may grow to 15 feet deep. Its extensive rhizomatous growth allows it to form large clones. Canada thistle's ability to rapidly spread both by rhizomes and prolific seed make it particularly difficult to manage. Canada thistle emerges as a small rosette in late -April to early -May, but new shoots can emerge during most of the growing season. Leaves are irregularly lobed with small spines along the margins. The upper surface of mature leaves is dark green, with a paler underside. Mature plants reach two -five feet in height and begin flowering in June. The numerous magenta florets are arranged in W-1" diameter heads. By July the seeds are windborne on their delicate pappus, and can be found throughout the landscape. Canada thistle may produce 1,000 to 1,500 seeds per flowering stalk and seeds can remain viable in the seed bank up to twenty years. Canada thistle grows in meadows, prairies, fields, pastures and waste places with a variety of site conditions including full sun or part -shade exposure, and wet or dry soils. Mechanical Mowing or cutting Canada thistle may be effective if repeated on a regular basis until the plant's root reserves are depleted. The optimal time to mow Canada thistle is when the buds are formed or early flowering stage. Mowing should be avoided after seeds have developed, as it may disperse the seed. Clipping and bagging seed heads can be done in smaller populations.