We just finished a video on how to control Canada thistle using the Green Shoots foam herbicide system (link).  The video shows how our small foam herbicide dispenser creates a thick foam herbicide that sticks well to leaves and green stems.  In the video we use the small foam herbicide dispenser and physically wipe small amounts of foam to the leaves and green stem.

Foam Herbicide Applied to Canada Thistle

We are using glyphosate herbicide with the wiping technique.  The label that accompanies the herbicide you use should explain more about herbicide wiping.  Many labels recommend a

10 Days after Application – Thistle Is Completely Dead

33% to 100% solution for use with wiping.  However, you can use a less concentrated herbicide solution than that.  We are using a 10% concentration in this video.

Background on Canada Thistle – Canada thistle (Cirsium arvense) is an invasive thistle in North America and is identified as a noxious weed in many states. It is an exotic or non-native species brought to North America from Europe (not Canada!) possibly as early as the 1600s. Since that time, Canada thistle has invaded prairies and grasslands, especially in the Midwest, Great Plains, and southern Canada.  It out-competes desirable, native species like grasses and wildflowers. In this way, Canada thistle degrades wildlife habitat and reduces ecological diversity.

Canada thistle has rhizomes (underground stems) that grow laterally and up to a depth of about 3.5 feet.  New shoots develop from the rhizome and thus a stand of Canada thistle might orginate from one rhizome.

Other common names include: Californian thistle, Canadian thistle, creeping thistle, field thistle, corn thistle, perennial thistle, field thistle. For more information on Canada Thistle, visit the United States Department of Agriculture National Agricultural Library (link).