Glysophate and Crepe Myrtles

From what I've been told, it's almost impossible to kill a Crepe Myrtle.

Glyphosate must be absorbed through the leaves of plants…won’t hurt if you spray it on the roots of your crepe Myrtle

One of the safest things you can do. And it degrades in just a couple days to a week so you can replant quickly. Just make sure it’s actually glyphosate. The new roundup formulas don’t use it anymore.

EDIT: I miss read the OPs post. He is trying to kill Jasmine roots growing adjacent to his Crepe Myrtle. My response below is for killing Crepe Myrtles. One thing I will say about my experience with Triclopyr is that I had regular Nandinas growing into Encore Azalea bushes. Triclopyr will kill both. I had to basically paint the Triclopyr onto some of the Nandina leaves. Any drops that accidentally touched Azalea leaves, I immediately cut those leaves off. Three weeks later the Nandinas were dead and the Azaleas were fine. So whatever poison the OP uses, I would be super careful to not get any poison on Crepe Myrtle leaves or root suckers.


Per an AI response: To effectively kill Crepe Myrtle, consider using a systemic herbicide like triclopyr or a phenoxy herbicide such as 2,4-D or dicamba. These herbicides can target the plant's roots, preventing regrowth. You can also use sucker stoppers which are plant growth regulators.

I've used Fertilome Brush Killer/Stump Killer to kill practically impossible to kill regular Nandinas recently. It contains 8.8% Triclopyr and did the job, but it took several weeks. I had tried Tractor Supply's Glyphosphate product about a month before and it did nothing to kill the regular Nandinas.

Fertilome Brush Killer/Stump Killer has a much higher percentage of Triclopyr compared to Roundup Poison Ivy/Tough Brush Killer which has the following active ingredients:
Triclopyr, triethylamine salt ... 0.122%
Fluazifop-P-butyl ... 0.097%
Diquat dibromide ... 0.073%

I was at a Garden center that had other Triclopyr products in higher percentages than Fertilome. All were pretty expensive.

I'm not saying Triclopyr will work on Crepe Myrtles but an AI response using a Google search said it would, and Triclopyr killed my regular Nandina bushes which are as hard to kill as Bamboo.

Yeah, I misread your post just like everyone else. I put another paragraph at the beginning of my last post. I would try Triclopyr but be super careful not to get any on any crepe myrtle leaves or sucker roots. If you have Jasmine roots and Crepe Myrtle sucker plants growing into each other I would not spray that directly. It is absorbed through the leaves and takes a few weeks to kill brushy plants.

Here is the AI response:

What chemical kills Asian jasmine ground cover?
3. Herbicide Use:
Glyphosate:
Products like Roundup (containing glyphosate) can be used to kill Asian jasmine, but careful application is crucial to avoid harming surrounding plants.
Triclopyr:
A Reddit user says they used Clear Pasture (containing triclopyr) to kill Asian jasmine, with success, while avoiding damage to trees.

Tractor Supply sells Glyphosphate.

Nothing kills crepe myrtles

quote:

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Nandina bushes which are as hard to kill as Bamboo

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I had a nandina thicket that needed to go growing around a crepe myrtle. My yard guy struggled with it. He tried shears on the stalks and an ax on the root mat. Finally, he rented a small walk-behind stump grinder and chewed the roots out down about 6 inches. That worked to remove the nandina, and the crepe myrtle didn't seem to be impacted at all.