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I have a large number of mature buckthorn shrubs in my yard that were there when I purchased the property. This is classified as an invasive in North America. Not only is it problematic in terms of spreading in my yard, it produces copious amounts of berries which birds then carry to other areas. When I go hiking in the area, I see these plants taking over and I really want to eliminate them completely.

This summer I started by removing branches from half a dozen or so and cut them down to low stumps. I then dug out the stump of one. It turns out that cutting them low was a bad idea because these are really tough plants and there were multiple thick roots extending straight down into the heavy clay soil. I really could have used the leverage to get at them. I spent probably 4 hours on the one plant and was exhausted. I have maybe 5, 6, 10 dozen more to go. Meanwhile they continue to drop berries like crazy and all the stumps that were no removed are resprouting. I tried driving some bits of copper wire into one on the off-chance that might kill it but that didn't seem to do anything.

I'm resigned to the belief that I will not able to remove them fast enough. I need to somehow kill these plants to stop the spread. The best resource I've found for advice on managing them is here. It mentions putting a can over them to prevent re-sprouting but I'm hesitant to cut them low and lose the leverage I will want later.

That leaves chemicals. The options listed on that site are:

  • Triclopyramine
  • Triclopyrester
  • Glyphosate (Roundup)

I would really prefer not to use conventional herbicides for various reasons. I'm looking for other options that would be more along the lines of organic methods. If that's not an option, are there any of the above that are considered more safe. I say that knowing that often all that means is that we know less about newer chemicals. I'm just looking for information at this point.

I found a page saying that epsom salts can be used to kill trees. Anyone with experience using this approach? Any risks to this for the soil? There are some other plants in the beds that we would like to keep hoping they will fill in once the buckthorn is defeated.

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In addition to the document you reference note that Ontario has done quite a bit of work on this subject too. See this publication for example. Heavy pruning followed by dedicated consistent shoot removal is one option, but a time consuming one.

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You missed your best chance to kill them, which would have been to paint the stumps with brushwood killer - but you need to do that immediately after cutting, so plant will carry the chemical down into its roots before it "realizes" it doesn't have leaves any more.

The next best option is probably to spray ALL new leafy growth as soon as the leaves start to appear, and cut off the sprayed growth about a week after spraying, whether or not it appears to have died. Repeat for as long as it takes to stop them re-sprouting. That may take several months. You need to keep right on top of this. If you let them regrow for a month rather than a week before zapping them again, a lot of your previous work will have been undone.

Personally I wouldn't bother about trying to choose a herbicide that won't damage other nearby plants, or grass. There will be plenty of time to fix that once you have got rid of the buckthorn - and that might take more than one year's growing season.

If you want to get rid of the roots as well, leave them for one or two years after the plants are dead, so they start to decay naturally. They will be easier to dig out that way - once the roots start to rot, a sharp spade should chop through them so you don't need to dig out the entire root system in one piece.

As a chemical-free alternative, hire a stump grinder and shred all the roots. Warning - using a stump grinder is physically hard work, so you might prefer getting a professional to do the job for you, even if it costs more than hiring the tool to do it yourself. Grinding out "10 dozen" small stumps (say less than 6 inches diameter) in a day is quite possible, unless there are access problems (steep slopes, rocky soil, working close to buildings, etc) that slow the job down.

  • Not much opportunity missed. I've only touched the tip of this particular iceberg. I've managed other weeds by going after the leaves but this stuff is really nasty. They resprout very quickly and there are too many to keep up with. I'm really looking for non-conventional herbicides here but thanks for the answer. – JimmyJames Sep 19 '18 at 18:02
  • You can use triclopyr ester as a basal spray - it needs to be diluted in oil, but can be applied now and into the early winter. You can kill ALL of your buckthorn yet this year, then cut the trunks down as you have time. See here: aces.edu/timelyinfo/Ag%20Soil/2010/December/Dec_2010.pdf – Jurp Sep 20 '18 at 0:56
  • @Jurp I have kids so using poison with potential carcinogenic and reproductive risk factors in broad areas of the yard isn't really something I am considering. – JimmyJames Sep 20 '18 at 14:00
  • Then you're stuck doing it manually. I've removed dozens (hundreds?) of buckthorn in the past, and found that they were very shallow-rooted. If they were 3-4" in diameter, I could usually cut all of the roots within about 6" of the trunk, then push the small tree over. Quite satisfying, actually, I would then bag the berries for the garbage and burn the wood after it dried. For me, maybe one in 15 had deeper roots. If you decide to try this, you won't need to treat the shallow roots.; if you get a deeper-rooted one you could use triclopyr amine on the roots, let it dry, and then bury the roots – Jurp Sep 20 '18 at 22:59
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Glyphosate is relatively safe to use. While there currently is some data about health effects, they are long term with chronic exposure. It breaks down in the soil. Of the various herbicides I've read about it is the least bad.

Buckthorn is fairly salt tolerant. I would be surprised if epsom salts worked.

If you are totally anti-chemical, try this routine:

stage 1 preliminary cut.

Remove the shrubs at roughly knee height. This is fairly fast, as you are hauling most of the shrub in 1 or 2 chunks.

stage 2 exposing root collar

With a heavy hoe, grubhoe, or pulaski expose about an inch or more of root. You are just clearing the way to use tools to cut it off lower without wrecking the tools with dirt on sharp edges.

stage 3 secondary cut.

Using lopping pruners or chainsaw, cut the stem a bit below the previous ground level. If using a chainsaw, take care to keep the tip out of the dirt, and watch for kickback. If using lopping shears you can get more leverage by kneeling at right angles to the trunk, bracing one arm of the loppers against your knees, and using both hands on the other handle.

stage 4 fill in the holes

Fill in the holes by the stumps as best you can. A rake used tines up works well for this.

stage 5 mow.

The shrubs will sprout like crazy. Mow. A mower will handle new growth up to about 1/4" diameter without a problem.

By cutting them off below ground and filling in the holes, you enable fairly easy mowing. You will have to mow for probably a full growing season, possibly two.

Buckthorn is a desert plant. Seeds will stay viable for a long time. You will have volunteers for several years. I suggest that you leave it in either lawn, or some form of annual bed that you can rototill on a yearly basis.

  • Thanks for the information. I tried the epsom salt thing on a few of the smaller stumps that I haven't pulled. I'll update on whether there seems to be any progress on that. It did seem to drink the brine quite readily. I had to fill and refill several times. – JimmyJames Sep 24 '18 at 13:46
  • I have a weed torch which I have used to know back the sprouts. I've become a little wary of using it since the vapor/smoke of some plants can cause allergic reactions but I don't think that's a major issue with this. I've been mowing these horrible things for a while since they want to invade the lawn. Mowing in the beds is problematic since we want to leave the desirable plants and the ground is not level and rocky. I can use a line trimmer if nothing else. – JimmyJames Sep 24 '18 at 13:48
  • Weed torch will work better (less fumes) if the foliage is wet. Don't burn it, just cook it lightly. May be worth while to either remove larger rocks, or bury them enough that your mower can work on it – Sherwood Botsford Sep 25 '18 at 0:14
  • Yeah, I've used the torch extensively and know burning is just a waste of fuel. Some plants will give off vapors that are irritating to lungs and eyes even when not burned. Creeping charlie is one that I don't torch anymore and instead use food strength vinegar to good effect. – JimmyJames Sep 25 '18 at 13:26

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