CANADIAN THISTLE
BACKGROUND INFORMATION
Canada Thistle (Circium arvense) is a colony forming perennial weed that reproduces by seeds and root buds on spreading lateral roots. Most plants are woody with grooved stems growing 1 to 4 feet high. Mature plants have a deep and extensive root system growing down to a meter under the soil surface. Canada thistle reproduces asexually from rhizamatous roots (any part of the root system may give rise to new plants) or sexually from wind-blown seed, which germinates in the late spring or early fall. Seeds may retain viability 4+ years in the soil. New seedlings develop into rosettes. Purple flowers are produced in July - August. Canada thistle is a problem in perennial and annual crops, rangeland, and minimum tillage systems, such as peppermint.
HOW TO GET RID OF THE CANADIAN THISTLE
Most of you are probably familiar with this noxious, perennial weed. One
way to control it is by cutting it down to the ground several times a season. This will starve even thistles tough plant roots and kill it. In large, heavily infested areas planting a smother crop of alfalfa or buckwheat after mowing the thistles has proven to be very effective. Alfalfa is so aggressive in its search for moisture and nutrients it can eradicate thistle. The alfalfa can then be tilled under in late summer to enrich the soil. One method used in small areas is to inject apple cider vinegar or plain white vinegar into the center of the thistle. Use a veterinarian type syringe to do this so the solution is in contact only with the target plant. This has worked so well that the thistle shrivels up, dies, root and all! Vinegar does act as a soil sterilant so you must be careful what it contacts.CANADIAN THISTLE ROSETTE
CANADIAN THISTLE FLOWER
MATURE CANADIAN THISTLE