DefinitelyDressage.com

My DD has moved into a home where the vegetation had been allowed to grow rampant. We have chopped it down and applied Roundup as well as some other "natural" remedies (I think one had salt included in the recipe) to no avail. The crap keeps coming back! She doesn't even care if the grass gets killed at this point. Any good solutions for killing these weeds which grow into trees?

Treat the trunks as soon as they're cut - two person operation. Wear gloves, goggles and masks and mix the stuff four times as hot as recommended. BTW, if you're buying it "premixed" stop wasting your money.

The trick to getting rid of brush that you don't want is to put a small amount of fertilizer into your weed abatement treatment.
We had 20' tall oleanders on our place when we moved in. On top of being highly toxic, they are very hard to kill.
You have to treat first, before trimming and give the treatment time to move into the roots and then cut it down.
We put about a teaspoon of fertilizer in the brush clearing herbicide and it worked a treat.

Yes, that's another attack if the foliage is smaller than something you'd use a chain saw on. Let the product work for a couple weeks until the foliage is dead and dry.
I've heard about the fertilizer addition and never used it, but it sounds like it has potential. Depending on the time of year and it's vascular system, every plant has a timeframe within which the plant absorbs anything to the root level. In Michigan, there is a great flow up and down in the Spring, then a greater flow down beginning in August, with movement halting by November for most plants (speaking broadly).
If it's Spring, and the plant is a shrub and too tall to safely spray, cut to a couple feet off the ground, wait until new leaves begin to sprout from the remainder, then spray a systemic herbicide.
What is it you're trying to kill?

I was going to ask the same thing... what is the plant(s) you are trying to kill?

Might make a difference in the removal strategy. Some plants are incredibly hard to get rid of.

I'll try and get photos of the weed/tree.

I would contact your county ag extension office. They probably have a helpful weed/plant specialist on staff who can offer good strategies.

Some plants as they mature get a coating that protects them from herbicides, star thistle is one, if it's mature you have to wound it first. Smaller fresh growth is easier to kill. Cut it let it grow a few leaves then spray.

I fight weed trees endlessly ... mulberry, elm (Siberian or slippery/red), boxelder, black walnut, silver maples, sumac, some kind of locust. And the shrubs -- buckthorn and honeysuckle. For separate trees (not colonies like sumac), dig all you can. If they can't be dug, cut to the ground and paint with stump killer. When they re-sprout, cut and paint again. Endlessly. Eventually you wear them out.

There is also the buckthorn baggie trick which I think works on other trees/plants. http://news.wisc.edu/buckthorn-baggie-k ... chemicals/

Boxelder are among the worst!! In addition to your Ag Agent, check with your Conservation District folks if your office isn't far away.

I found that if I just mowed consistently, the weeds would die out and the grass would take over. I did fertilize as well.

I second the motion for contacting your county ag extension agent. There are some herbicides available which are more targeted to certain species, but their use requires having either a commercial or private applicator license (I've had mine for 20 yrs). My understanding is that Roundup, although quite effective, can bioaccumulate in the soil. Use wisely and sparingly because Roundup is non-selective. Also, as mentioned, some pesky plants need to have leaves remaining on which to apply herbicides; some take up herbicides better under certain conditions (soil moisture, new plant growth, etc) all of which your ag extension folks should know about.