Monroe County Master Gardener Association

Did My Herbicide Do That?

Would you like your weed killer to last all summer long? Would you like it to start working faster? Are you tired of those Herculean bullies staring you in the face for days as if to say, “Ha, ha! I’m still here!”

STOP!

While attending a class at the Wildflower Association of Michigan Conference, I was amazed to find out what had been going on in the world of herbicides. Dr. David Roberts, MSU professor, was called by a homeowner to visit his woodland yard and find out why certain trees were declining. There was a stone path running through his yard, and the homeowner had always sprayed the path with an herbicide to keep the weeds in check. Why were unsprayed trees dying? After checking the herbicide that was used on the path, Roberts found that “Roundup Extended Control” had been used on the walkway, which included not only glyphosate, but also imazapic and diquat Di Br, dubbed “Roundup on steroids.” Yes, his herbicide did that. The homeowner lost two hickories and one oak which were 20 feet away from the path.

On another occasion, a homeowner called to find out why his wife’s favorite plant – a hydrangea – had several distorted, cupped-shaped leaves on certain branches. The caller was sure that he had not used herbicides. Upon further investigation, a jug of “Roundup Extended Control” was found in the garage and had been used on the adjacent side of the house, leaching through the soil to the hydrangeas. Yes, his herbicide did that.

This news greatly alarmed me because I use Roundup on certain weeds which consistently outperform me! I certainly don’t want to be surveying my dying trees while saying, “Did my herbicide do that?” What to do?

Be aware that herbicides can be “enhanced” with other herbicides (possibly because of expired patents) and make sure you know what you are putting on your property. There are many names of products … too many to list here …which can have unintended consequences. Roberts emphasized two ingredients which homeowners should never have:

IMAZAPIC IMAZAPYR

They are deadly, systemic, long-lasting (a year +), and mobile (they leach through the ground by gravity and rainwater.)

Also, be aware when you buy bulk mulch, soil, or even plants-ask the nursery or greenhouse if they have been sprayed. Remember, these herbicides can last over a year.

Again, what to do? I will continue to use glyphosate (to the horror of some of my family members) because I feel it is the best choice for me … I just won’t use “enhanced” glyphosate. Roberts himself recommended it when one class attendee asked what she should do to control poison ivy. He recommended glyphosate at a higher concentration than normal, with a surfactant.

Thank you, Jennie, for telling us to read the labels on the products we use. We must not be content to read just the front of the package. “Roundup – Max Control 365” contains imazapic, yet advice on the container said “… for use on driveways, patios, sidewalks, and gravel areas.” Well, the pictures I saw at class really brought it home to me. Read the labels… read the labels…read the labels.

Finally, here is my disclaimer: As much as I tried to share this info perfectly, my article may not be perfect. I was writing furiously on the margins of my program and the outside of my manila envelope because there were no handouts! More perfect information may be obtained at: treedoctor.msu.edu

article by Joan Otter