Canada Goldenrod (Solidago canadensis) is a native to Wisconsin but isn’t considered a highly prized prairie plant. Its Coefficient of Conservatism is a 1; making it, essentially a glorified weed. It’s often confused with Missouri Goldenrod (Solidago missouriensis) and sometimes with Showy Goldenrod (Solidago speciosa). Regardless of how careful you are to keep this out of your prairie, it will show up. It loves disturbed ground, which means areas where you heavily herbicide or burn; Canada Goldenrod can often be the first plant colonizing an area after a disturbance. There is some speculation that it is allelopathic and that it does not allow the germination of many seeds. It also is long-lived; a stand in Iowa was thought to be over 100 years old. Its rhizatomous growth and clonal habit makes it difficult to control but its ability to crowd out more desirable plants and create a monoculture make it important to control.
We found a method that works very well. Let me describe our process of arriving at this treatment. We tried cutting it with a handheld pair of hedge trimmers then spraying it with a 20% glyphosate solution but the spray caused too much collateral damage. We thought we could minimize this by surrounding the Canada goldenrod clones with cardboard and just lightly spritzing the tips with a downward angle on the bottle but you can see from the picture how much overspray occurs. I would not recommend this type of treatment.
We did continue with the cut and treat method but found some tools that reduced collateral damage to virtually nil. Working with the 20% glyphosate solution and cutting when Canada goldenrod is in flower, we changed the technique for applying the herbicide. By using a painting trim brush (one that is not a sponge) and a tallish container for the herbicide, we found we could gather enough herbicide in the brush without dripping it. We would tap this on the cut end and get complete coverage without dripping – no dripping down the stem and no dripping from the herbicide container to the cut end! We used a tallish container so the brush would stand upright and the handle would not slip down into the herbicide.
On August 17, 2013, we did a test in a small area to see how this would work. Within a week, we were seeing results. On September 4, 2013, this is how one of those test patches looks! You can see from this picture that we would have had a good deal of collateral damage had we continued with the spritzing method. Other advantages of this method of cutting and treating include being able to cut 1 stem or multiple stems and it uses minimal herbicide. The downside of this method is that it does not translate to operations wanting/needing to automate the process.
Although our method included one person cutting and one person treating, we figured out a method that functions well for a person working alone. Using a fanny pack, I was able to find a tallish screw-lid glass jar that would fit in it. I had to cut the handle of the trim brush slightly to fit inside the jar. When I wasn’t cutting, the herbicide and the trim brush were secure in the fanny pack with the lid on.
It sounds like a tedious process but frankly, it’s more boring than tedious. Jim and I work on Canada goldenrod for a couple hours each day, eventually we’ll be done or the bloom period will be over. It’s also important to note that the plant does not bloom until its second year; if these stems get treated the first year, we have eliminated a good deal of potential seed. Our strategy is that the areas we don’t treat this year will be where we start the following year. Our goal is to minimize the amount of Canada goldenrod we have. We have no illusion that we will ever eradicate it!
The following year, we did a follow up posting about the effectivness of this.