Drilling holes in the stump (unless done very close to the bark, so as to reach the phloem) is ineffective. What you need to do is to apply a concentrated herbicide like glyphosate (RoundUp, Gly-4, etc) or triclopyr (brush-b-gon, etc) to the freshly cut phloem. Since you are working with root suckers, a second application (or even possibly more) may be necessary. CrApe myrtles can pretty persistent. Be sure to treat all the suckers at one time (rather than doing a few now and more some other day). If the stump had been treated originally, it would have been very easy to take care of it to start with.

I sure hope you don't plan on growing anything else in the spot for a long time. It sounds like you have a real mess on your hands with the salt and whatever else you've tried.

Hire someone to bring their stump grinder in for 15 minutes, or rent one yourself!

But even with that, you won't be able to plant there for a looooog time, as brandon has mentioned.

Also, the root ends (left from the stump grinder) will almost certainly sprout. I'd try to kill the stump before removing it to avoid this problem. Maybe it won't matter if it's in the middle of the yard where the root sprouts can be mowed down.

We have a few others that are in nice spots, it was just this one that we looked at it and said "what were they thinking???"
Yeah I don't plan on growing anything there anytime soon, but I've been having to spray weed killer to keep the grass and weeds from growing up with the CM. Will get some of the products listed this weekend and start spraying the crap out of it!

One more question tho, after we spray it, should we lay down black plastic or anything to block out the light? Or would that just be a waste of time?

Thanks for all the help so far! I hope it works. Been battling this tree for years.

We had two Crape Myrtles at this house when we moved in. One we decided to keep, the other we wanted to go. We cut it to the ground and ground the stump, then put black plastic over the root ball. We do still get suckers (3 years later), but I just keep pulling them out and hoping it will eventually give up. :)

The second one, the one we kept, is planted like three feet from the corner of the house. :( Obviously not ideal, but it does do a good job of anchoring that corner. We only kept it and two Boxwoods in the foundation planting. I wasn't under the impression that they had really damaging roots - was I wrong about this?

The roots on ours cracked our driveway and the branches damaged the gutters on our house (knocked a section down completely in a storm) We would have trimmed the branches, but we would have ended up with a lopsided half of a tree. It was only a little over a foot away from the driveway and about 4 feet from the corner of the house.
Really you want to avoid planting any big trees right next to a house like that. as they grow they can damage the foundation. (not to mention the branches can cause extensive damage to your roof if you don't/can't trim them) Trees tend to have really big root systems, the CM we have shot roots out underneath the driveway and had new shoots popping up in our flower bed. (Luckily I was able to kill those off.)

1. I, too, moved into a house that had 3 huge crepe myrtles. Since then a 4th one has grown. The original three have probably been here since 1994. Trunks are 8 to 10 inches in diameter (maybe more). I'm having them cut out and the stumps ground up. A root is groing under a sprinkler system pipe. I have to get rid of the root, also; so the roots won't cause any more damage to anything, but especially the sprinkler system. Should I leave the stump, or is it okay to grind it up and still get rid of the roots?

Shibamom, I am a little confused when you say that you are having your crApe myrtle stumps ground up but then also asking if you can leave the stumps. If you have the freshly-cut stumps properly treated with glyphosate (or other appropriate herbicide), there's no reason to remove the stumps unless they are in your way or you don't like the look of them being there. If they are dead, they aren't going to cause a problem with your sprinkler system, etc.

My vote would be alternating between carefully applied round up when the sucker sneak up on you and just mowing regular like when the rest of the year.

These things really that much of trouble down south?

Did you ever get rid of the crape myrtle you were having trouble with near your driveway???

So glad this thread was revived. I just had a large CM removed for all the above mentioned reasons and it was right next to driveway. The tree was removed one week ago and stump was not treated. can I still apply the chemicals so it doesn't keep producing suckers in the springtime or is it too late?

Teeka, how high was the stump cut? If there's enough stump left, cut down two or three inches lower to expose fresh phloem. The current top of the stump (not freshly cut) will not likely absorb any herbicide, as compartmentalization will have begun. Ideally, it should have been treated as soon as the plant was cut down, but if you can reopen the vascular system (phloem), you may be able to take care of things. If not, you can try once enough sprouts have formed, next year.

The best way to get rid of it is to scar or freshly cut the stump, then you can buy a chemical call Tordon RTU which has a spout like dawn dish washing detergent, squirt it on the fresh open bark and it will not come back. The herbicide can be bought in a quart size and its not expensive.

Multiple herbicides could be used, IF application to fresh phloem is still possible. More information is needed from Teeka.

Once again, I'm going to re-revive this thread! I literally just posted asking if I have enough yard to plant a crepe myrtle. Doesn't sound like I do.... 25 ft from house to street, 18' from our driveway to the neighbors..... We currently have a mature carrotwood that I'm hating and want to remove, as I'm concerned about their roots. The neighbors also had a carrotwood, and the roots penetrated their water line and made a big, expensive, watery mess for them to deal with. The plumber thinks it's a matter of time before we have the same problem! I'm in Southern CA Zone 10 FYI.

Not sure how helpful this is. We had to cut down a tree in our yard that was in the way. We don’t like to use any sort of chemicals so we cut it down to ground level and dug out a trench around it as much as possible. Then we raked everything back away about two or three feet. Then we scored the top, stacked a little bit of old firewood around it and doused it well with charcoal lighter. We lit it and stood by for a few hours and watched it with the garden hose close at hand until it burned out then sprayed water on it to assure no fire danger. It’s gone. For good. This method is not for everyone. But it was successful for us.

Omigosh, i wish i had read ahead before cutting down this tree! Scary messy tree ... & now this! Previous owners planted three of them along the fence next to patio pavement (about 8" away!) I've just attempted to remove one of them. Now, i don't dare touch the other two, no matter how unattractive & messy. Pods stain the cement in heavy black streaks every year. And stains the umbrella & patio cushions & furniture. Three seasons of a variety of mess with what must be a twenty-five year old tree. I have heard of drilling many holes in stump, like a honeycomb, then using sugar water.

This might sound weird to you, but let the suckers grow into new trees. Then cut them to stumps and paint Roundup/glyphosate on them. Multiple applications may be necessary. Salt and bleach do NOT kill trees.

if the stump is not sticking up, just mow over the spot. Eventually, the tree will give up. I had a similar issue with a white poplar that I had cut down - sucker city. I just kept mowing. After about 2-3 years, the suckers stopped.