Canada thistle (Cirsium arvense) 

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Desription of Plant:
The stems and leaves grow 1.2 to 1.5 m tall and are ridged and branched.  The above ground portion of the shoot dies during the winter, but the under ground part generally survives to produce new shoots the following season.  The flower head is urn-shaped (like a vase) and the bracts are spineless.  The color of the flowers may vary from plant to plant, either purple, pink, or white.  Flowering occurs during July and August.  The seeds of the Canada thistle are 2.5 to 4 mm long and a straw to light brown color.  This weed reproduces by seed, but it mostly spreads by lateral roots sending up new shoots each year.

Useful Herbicides:
2, 4-D (Amine,LV Esters), 2, 4-D (LV ester), Touchdown 600, Tordon 22K/Tordon 101 

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Herbicide Brand	How to Apply	When to Apply
2, 4-D (Amine,LV Esters)	Broadcast	Before Full Flower Or Fall Regrowth
2, 4-D (LV ester)	Broadcast	Before Full Flower Or Fall Regrowth
Touchdown 600	Broadcast	Before Full Flower Or Fall Regrowth
Tordon 22K/Tordon 101	Broadcast	Before Full Flower Or Fall Regrowth

Further Information About These Herbicides:

Herbicide Brand	Active Ingredient	Mode of Action
2, 4-D (Amine, LV Esters)	2, 4-D (Amine, LV Esters)	Growth Regulator Herbicide
2, 4-D (LV ester)	2, 4-D (LV ester)	Growth Regulator Herbicide
Touchdown 600	Chemical fallow: Banvel, (or 2,4-D Amine) + non-ionic surfactant. Non-ionic surfactants: Agral 90, Ag-Surf, Frigate, Companion, Enhance.	Moves from the foliage into the roots and kills the entire plant.
Tordon 22K/Tordon 101	Tordon 101 plus Sodium TCA, Tordon 101 plus Sylgard.	Growth Regulator Herbicide

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By: Ryan Hunt             1/23/03 

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