Thistle weeds #344308 - Ask Extension

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Thistle weeds #344308

Asked July 18, 2016, 5:31 PM EDT

Hi, My question is with regard to spraying the thistle weed that has invaded my garden. It was suggested to me to use Roundup, but I want to know if there is a chemical less harmful to adults and pets that I could use. I don't use weed killers of any kind presently. I do have a dog. I just don't want any harsh chemicals around.

Baltimore County Maryland

Expert Response

With Canada Thistle the key to control is vigilance and persistence. Do not let the plant flower and go to seed. Mowing/clipping the tops whenever they appear will also help starve the roots. Other organic approaches include vinegar and soap sprays but are not effective as they burn the top growth only.
If you decide to use a glyphosate product as in Roundup, use a small paint brush to apply a non-selective herbicide to the cut ends of the top growth.  Follow label directions for timing of the herbicide. Please see the attached publication from the Plant Conservation Alliance for management optionshttp://www.nps.gov/plants/alien/fact/ciar1.htm
Contact the National Pesticide Information Line for toxicity issues http://npic.orst.edu/
mh

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