Faces Of Weed Death

Yes, I know weeds do not actually have faces. But these pests are the single biggest reason lawn care companies lose customers and need to be killed. They are also the reason why a lot of us have jobs (Thanks, Mr. Dandelion).

You spoke with your ATS rep, purchased a high quality weed killer, read the label, and applied per the label (hint, hint, hint, hint). Now, what can you expect? Well, the death of the weeds, of course. So, here is the part where I try not to get too technical. Please keep in mind I am painting with a wide brush and only wish to share basics. This should not be too hard; it’s only been 20 years since my college days.

Death will/should come in various ways depending on the weed in question. In most cases, we must have “actively growing” weeds for herbicides to have the proper effect. This basically means weeds are not stressed due to drought or other extreme weather conditions. A lot of our herbicides depend on water movement within the target plant.

Most of the time, selective broadleaf herbicides will cause “epinasty” (a downward twisting of the stem and leaf petioles) within a few hours of treatment. This twisting is a good sign the weeds will eventually check out via growing themselves to death. Dandelions will become necrotic (brown & crispy) and then turn to dust.

Epinasty is pictured above.

What about crabgrass and sedges? With these weeds, do not expect to witness changes for days. With proper application, weed growth generally stops fairly quickly. Though that can be the case, crabgrass and sedges frequently continue to look perfectly healthy. For these critters, you need to examine the growing point, which is around the upper most leaf. Pull that leaf straight up out of the plant and, hopefully, you’ll see the face of death. You want to see a brownish mushy base to that leaf, which indicates the growing point is feeling the pain of the herbicide. In contrast, if the base of said leaf is bright white and firm with moisture, there’s a good chance these weeds are feeling fine. I suspect they got missed or somebody forgot to add the surfactant.

What about weeds treated with a non-selective like Roundup or Glyphosate? Depending on the version chosen, this too can be a slow and tedious death. Early indications of a successful kill are stunted & chlorotic (yellowing) looks to the newer leaf tissues. Sometimes older parts of the weeds turn purple to reddish before they turn necrotic and are eventually desiccated. I personally have seen this take as long as a month in some conditions, especially for something like the dreaded Canada thistle. 

In the future, I hope to come up with a death ray that will selectively vaporize weed pests. Until then, the aforementioned indicators should give you some comfort that your applications are working. If you encounter any questions, contact your local ATS rep. They can help you quickly.

Tim Yingling  
ATS Representative