Options to kill/remove invasive buckthorn

Question

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.

Answer 1

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.

Answer 2

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.

Answer 3

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.

Answer 4

I'm going to experiment with dousing cut buckthorn stumps immediately with industrial-strength vinegar. I'm using 45% acetic acid straight. I also use this product 1:2 with water in replacement of glyphosate and it works great, at least at the scale I need it for, for general weed control. You just have to be careful as it is non-selective and will kill anything green. Will it work on buckthorn stumps...tbd.

Answer 5

Sorry to bring back an old thread, I have a question as well as a contribution.

A great method to kill buckthorn is to cut the stump to the ground then apply glyphosate, 18%+ concentration, to the perimeter of the stump using a Buckthorn Blaster. The Blaster really reduces the amount of glyphosate used, there is no overspray, it also is very easy and fast as well as protects the user. I have have a 100% kill rate as fr as I know with this, done in the fall or winter. I have killed hundreds of big BT with one 16oz bottle.

My question is about using salt pellets injected/inserted into the standing tree. I want to try this technique using water softener salt pellets. Cutting can be dangerous, time consuming, disruptive. If I can walk through the woods with a lithium drill and a backpack full of salt pellets, just slaughtering the buckthorn, I'd be a happy man. I'd drill in about 2cm, near ground level, and pound in 1 to 3 pellets depending on the size, each in their own hole. I think a slightly downward facing hole would cause rain water to trickle in, become extremely saline, and then travel through the plant, both up and down, depending on season.

When I hear that spraying a salt solution on some plants will kill them, I feel that injecting a pellet, with long-term salt delivery, would surely be fatal.

-No herbicide -No cutting -If it works, it would probably work year-round.
-Cheap, easy, safe, FAST!

Thanks