How to successfuly destroy invasively sprouting Black Locust tree?
September 20, 2016 11:59 AM   Subscribe

The city electrical utility cut down a Black Locust tree in our back alley that was growing into the power lines. Before you clutch your pearls, this is a fast-growing, invasive tree that is considered a weed in my region (Seattle, King County, Washington), so getting rid of it is a good thing. I have also planted a couple of other, nicer, trees. The problem is that the stump is multiply and rapidly sprouting and it has a violent will to survive. How do I deal with the stump and its sprouts so that I don't end up with 15 additional locust trees?

They are showing up elsewhere in the alley and the yard and even the neighbor's yard. I asked an arborist, who recommended stump grinding, but I am skeptical because that solution doesn't address the fact that the sprouts will just make new trees elsewhere. Online resources recommend treatment with glyphosate herbicide, but I would want to have a professional do that because I'm concerned about chemical hazard. Other resources recommend covering it with a tarp for a couple of years to cut off sunlight, but that's not ideal for a variety of reasons.

If you have successfully dealt with a Black Locust ex-tree that was sprouting, how did you do it? Is the herbicide treatment the best way? What sort of professional would I call to do that? Another arborist?
posted by matildaben to Home & Garden (16 answers total) 2 users marked this as a favorite
Oh, yeah, I have one of these.

I think the tree can sprout from whatever roots are left over in the yard. Ours was cut down THREE years ago and I'm still pulling sprouts. We did grind the stump, fwiw, and I'm still dealing with sprouts. (Stump grinding was not very expensive, as I recall. A couple of hundred dollars? My memory is fuzzy.)

As for the sprouts, I just pull them out (wearing gloves if I'm on top of things; the thorns are no joke!) For sprouts that are, for whatever reason, not pullable (too big, growing out of a wall in a weird way), I cut them to the ground. They can't keep regenerating forever right???

It's not ideal.

Glyphosate is something that I have used in the past, but I don't bother here, because pulling them out or cutting to the ground works just as well. Which is to say it doesn't work that well, because these trees are extremely persistent.

Good luck! and I'm sorry! I feel your pain.
posted by purpleclover at 12:07 PM on September 20, 2016

We have many black locust in Missouri - this article from the Missouri Dept. of Conservation should give you some tips.
posted by jferg at 12:27 PM on September 20, 2016

Wait, let me correct something I said:
Glyphosate/Roundup would work better than cutting down sprouts to the ground. They can resprout if you just cut them down to the ground, whereas Roundup will kill the whole root.

However, if you pull them up root and all, I think that's the best you can do. There's no chemical solution that's more effective.
posted by purpleclover at 12:37 PM on September 20, 2016 [1 favorite]

After reading the link that jferg posted, I feel like you may have a long-term control situation on your hands. You are going to have to weed these sprouts repeatedly for years, and they may never stop popping up. The Missouri page seems to suggest that just mowing them might be enough to stop them from ever getting past the sprout stage, but that they are likely to keep popping up and controlling them is going to be an ongoing process. The good news is that it doesn't sound very hard to control them at a very minor level, as long as you stay on top of it.
posted by Anticipation Of A New Lover's Arrival, The at 12:39 PM on September 20, 2016

When the ailanthus trees in my backyard were cut down by my electric utility, they sprayed something (herbicide) that prevented regrowth. Can you call the city and see if they will do the same thing? It seems that this will prevent them from having to cut the trees down again in 20 years.
posted by H21 at 12:40 PM on September 20, 2016

We had a different species of tree resprouting in the backyard, and herbicide was the best answer. We sprayed sprouts with triclopyr, another common herbicide. You can also cut sprouts and paint the stem, but since it's fall, the tree is translocating nutrients from the leaves, so it will take in more herbicide if you treat the green leaves. Hire a licensed pesticide applicator if you don't want to DIY, but know you may need follow-up treatments. Ask if lawn and garden services are licensed. They should also know the most effective herbicide to use.
posted by momus_window at 12:42 PM on September 20, 2016

Sorry, I guess I should read below the fold fully. :-( Glyphosphate (RoundUp) is actually one of the less hazardous lawn chemicals to work with. You can buy concentrated RoundUp at the store in small containers - that, some nitrile gloves, a disposable paintbrush, and a disposable container are pretty much all you need. Simply cut the tops off the sprouts, and paint the undiluted RoundUp onto the open ends of the sprouts liberally. RoundUp is rain-proof in ~1 hour and the contact toxicity is very low after about 8 hours, and does not have long-lasting toxicity issues. It's used a lot because it can be used to kill the weeds and plants in a given area, and the area can be replanted within a week.

Barring that, a yard service is probably willing to do the dirty work for you.
posted by jferg at 12:43 PM on September 20, 2016 [1 favorite]

Drill a 1/2 inch hole vertically near the living edge top of stump fill hole with round-up concentrate.
posted by hortense at 12:47 PM on September 20, 2016 [1 favorite]

Standard approach to eradicating invasives is diligence (usually over several years). Herbicidal applications will never replace recognizing and pulling seedlings as soon as they're spotted.

I grew up on a farm, and got very used to ~monthly walks through fields with a group of 2-3 people looking for [insert species here] seedlings.
posted by late afternoon dreaming hotel at 12:48 PM on September 20, 2016 [2 favorites]

I'd also encourage you to avoid off-label use of herbicides should that be the route you take. I work in the regulation of chemicals, including herbicides, and off-label use (not using the product in the manner described on the label) is a big problem in terms of ecotoxicology. If a product hasn't been approved for a particular kind of use, as written on the label, then the company hasn't been able to show that use of the product in that way is safe by EPA standards. Just an FYI.
posted by late afternoon dreaming hotel at 12:50 PM on September 20, 2016 [1 favorite]

Regarding offlabel use, I don't know what Roundup is labeled for, but this is exactly what Brush-B-Gone and Sucker-Stopper are designed for. Instruction are to cut off the thing you want dead and smear the freshly bare end with chemical using the convenient paintbrush inside the lid. Sucker Stopper is designed to kill the shoots but not the parent plant, Brush-B-Gone is designed to take out hte parent also. Since your parent tree is already (mostly) dead and you want to kill everything, I'd go with BrushBGone.

Painting it on is very localized, there's no reason people in your house or neighborhood should worry once it's on, and painting it rather than spraying it is even pretty safe to the person applying it, assuming they're wearing gloves. If you're avoiding the chemical for a specific personal reason (eg you're pregnant, you're worried/phobic, you have a personal sensitivity to chemicals, you can't wear gloves, etc) then anybody else can do it. You can hire an arborist, a landscape company, a gardener/handyman, a teenager down the street, etc.
posted by aimedwander at 12:55 PM on September 20, 2016 [1 favorite]

Just to alleviate concerns, this is an on-label use of RoundUp:
Cut stump treatments may be made on any site listed on this label. This product will control many types of woody brush and tree species. Apply this product using suitable equipment to ensure coverage of the entire cambium. Cut trees or resprouts close to the soil surface. Apply a 50 to 100 percent solution of this product to the freshly-cut surface immediately after cutting. Delays in application may result in reduced performance. For best results, applications should be made during periods of active growth and full leaf expansion.
This product may be used in parks, recreational and residential areas. It may be applied with any application equipment described in this label. This product may be used to trim- and-edge around trees, fences, paths, around buildings, sidewalks, and other objects in these areas. This product may be used for spot treatment of unwanted vegetation. This product may be used to eliminate unwanted weeds growing in established shrub beds or ornamental plantings. This product may be used prior to planting an area to ornamentals, flowers, turfgrass (sod or seed), or prior to laying asphalt or beginning construction projects.
posted by jferg at 1:04 PM on September 20, 2016 [4 favorites]

Black Locust is one of the hardest, most durable, and most decay-resistant North American woods and is sought after by craftspeople and woodworkers of many stripes. As the old saying goes: 'how long does a black locust fence post last in the ground? Two years longer than stone' -- and you might be able find someone who would remove those sprouts for you just to have them. Arthur Lee Jacobson has been my most useful resource for all things tree-related in Seattle.

Urban logging is a thing, and the next time you have a tree on your property (as opposed to the parking strip, which belongs to the city) that needs to be removed, you might want to look into selling it. Twenty years ago a Black Walnut with a twelve foot stem was going for ~$5000, and I'd bet it's a multiple of that now -- and I do sometimes wonder whether trees with valuable wood are a little more likely to be found to pose a danger to power lines.
posted by jamjam at 1:17 PM on September 20, 2016 [8 favorites]

I would third the drill-and-fill that Hortense and jferg suggest.. Drill holes in the stump, fill with roundup concentrate. I'd do several holes, and repeat. Then maybe in the spring, squirt stump killer in there.
posted by k5.user at 1:43 PM on September 20, 2016

my trick with Roundup is to apply it with a patch of paper towel that is rubber-banded or tied with a plastic bag or plastic wrap, like a death-to-invasive-tree Band-Aid, and take it off a month later.
posted by childofTethys at 4:25 PM on September 20, 2016

It's just regular sprout patrol for the next several years. I use a shovel and knife them off with that just under the surface. I think it's been 3 years now and they are slowing, but still cut a few every couple months.
posted by Mei's lost sandal at 9:29 PM on September 20, 2016

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