How to kill tree roots

melissa_thefarm(NItaly)November 4, 2007

I know there was a post about this, and perhaps one I began myself, but I can't find them with a search. So I'm bringing up the topic again.

My elms have once again nearly killed one of my garden plants, this time the Tea rose 'Isabelle Nabonnand'. We must have prepared the hole too well. I discovered the elm roots when we transplanted our strangely picky Tea rose to see whether it would do well in a different spot. Now I'm out for blood (sap): every time one of our plants is attacked, out comes an elm. That is, if I can find a way to kill the roots, in the least toxic way possible. Anyone know? Digging out the roots is not an option, and I speak as a person who is a willing digger. Cutting down the tree is useless: it would just send up a hundred suckers.



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hoovb zone 9 sunset 23

Here, they cut the tree down and apply tree-killer chemical, e.g., brush-b-gone, right away, immediately after the cut, to the stump. This kills the tree and roots. Then later (months later, or the following year) they come back with the stump grinder and take out the stump.

This is not an "organic" solution, however.

    Bookmark   November 4, 2007 at 3:40PM
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stefanb8(z7 MD)

I can't see how you might kill roots alone without digging them; the least difficult (although by no means easy, nor inexpensive, and probably not the least invasive) roots-only solution would probably involve mechanical trenching and then laying in some kind of physical barrier so the roots couldn't easily re-colonize the area. You'd always live in fear that the roots would figure out a way back in, and no doubt they eventually would.

You could try girdling the trees with an axe or chainsaw to starve the roots to death before finally cutting the whole thing down, if you really don't mind killing the tree. Now is probably a great time to be doing that.

    Bookmark   November 4, 2007 at 4:51PM
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Thanks for the replies.

Stefan, you do sound shocked at the idea of killing trees. Believe me, elms deserve to die. These are scrubby, scruffy Ulmus minor, chronic victims of Dutch Elm Disease, that grow, die, and sucker on. Their roots go very far, looking for good ground, and when they find some (e.g. a planting hole), the questing root emits a dense mass of fine rootlets and completely fills the area of good soil, killing the garden plant in the process. It's an amazing spectacle. And cutting down the tree doesn't do a thing to kill it. I'm afraid girdling the tree would also encourage it to sucker. Any kind of heavy machinery is ruled out by the sheer steepness of the terrain which prevents access.

This rose bed runs parallel to a fringe of wood dominated by elms. We want the wood but not the elms, so are planting and encouraging flowering ashes and oaks in the area, much healthier and better behaved native trees. Gradually removing the elms would also give them more room to grow. We love trees, need and want a lot more of them, and are busy planting and encouraging them. But it is nearly impossibly to garden around elms.

hoovb, exactly what is brush-be-gone? How toxic is it, that is, what effects does it have when used according to directions beyond the tree itself? I'm resigned to having to use non-organic methods in this case.

I've heard something about cutting down the tree, drilling holes in the stump, and filling them with concentrated fertilizer. This is what I had in the back of my mind: does anybody know about it? It's not organic, either, but sounds like it might be the least toxic method, if it works.



    Bookmark   November 5, 2007 at 1:42AM
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rjlinva might be able to cut down the tree, drill holes into the stump and add 2,4 d-amine......I've used this stuff to get rid of some persistent problem plants.


    Bookmark   November 5, 2007 at 5:35AM
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Hoov's advice is good. The easiest and surest way to kill the roots is to give them a fresh cut then paint the cut end with a herbicide -- I use an old paintbrush and highest concentration of Round-up I can get. It works very well, but it works best during a season when things are actively growing. If your plants are slowing down preparing for winter, it would be best to wait till spring.



    Bookmark   November 5, 2007 at 5:39AM
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stefanb8(z7 MD)

Melissa, I wasn't shocked - I just wasn't quite sure you were resolved to see the trees dead. After further reading, trenching is the last thing you should do, because it will cause root sprouting the likes of which you've never seen before in that species. The best solution is definitely going to center around the tree's trunk.

I would probably recommend doing what the others have mentioned, then - even leaving the trees standing while they die from girdling or herbicide will probably only encourage more beetles to attack and spread the disease to more healthy trees. If people there don't worry about the spread of Dutch elm disease, then girdling could be a very useful tactic - just apply herbicide to the freshly cut region at the same time. The tree's top will then parasitize the roots, causing them to die faster, without the tree realizing what's happened.

Be very careful with the cut wood, if you're seeing Dutch elm disease; it should be either buried or stored very carefully to avoid beetles using it as breeding ground. Or maybe Europeans don't care about this problem as much as we do, in which case, I suppose it doesn't matter. Here is a page with more info on "tarping" if you're interested.


    Bookmark   November 5, 2007 at 6:04AM
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hoovb zone 9 sunset 23

Brush-b-gone is a total vegetation killer, probably 2,4 d-amine as Robert suggested. They applied it to the eucalyptus and alders we had taken out. They painted the cut stumps carefully. The surrounding vegetation, right up to the stumps, was not affected at all. Of course, YMMV.

You'll have to see what is used and is legal in Italy--different laws there.

I have read that glyphosate (Roundup) has to be diluted a certain amount so that the plant can absorb it. The concentrate is too thick and is less easily absorbed by the plant. For trees I haven't had good luck with Roundup. It isn't strong enough.

    Bookmark   November 5, 2007 at 11:48AM
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mad_gallica(zone 5 - eastern New York)

For honeysuckle, sumac, poison ivy, and other woody weeds, I've done quite well with Round Up diluted to brush strength. I've never seen this pre-mixed. It's at least twice as strong as the normal weed concentration.

    Bookmark   November 5, 2007 at 12:02PM
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Stefan, hoovb, Connie, Robert, mad gallica,
Thanks for all the useful input. I think I have the information I need.

    Bookmark   November 5, 2007 at 11:54PM
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I agree with Melissa, they need to go. Unfortunately, the main tree at issue here was in a neighbors backyard and was cut down years ago, but apparently not killed. The roots are destroying the floor of my garage and trees have sprung up in the chain fence separating our yard from the one behind; not to mention the seedlings popping up all over the place. Also unfortunately, the owner(s) of the property have been either unwilling or unable to do anything about it. I would like nothing better than to be rid of the tree and its issue once and for all. While I have asked around at home improvement stores and the like, I have been advised that there is nothing there that could be used to kill the tree. Help! I kind of like the cooking oil idea. I usually pour mine outside anyway, but it's always vegetable oil of some sort.

    Bookmark   January 8, 2011 at 12:24AM
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