Answer: The herbicide 2,4-D is very effective against dandelions; thistles are a little harder to control. You can spot treat them with a vegetation killer such as Round-Up. First cut the stems down, then spray Round-up directly on the cut stems. The herbicide will be transported down to the roots and kill them. Round-Up is a contact killer so be sure to keep it off your plants or you'll kill them as well.
Best wishes with your weed patrol!
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