I received an email with this question and my response.  Please add thoughts you might have on a solution...


I am currently under a forestry practice contract through EQUIP.  [a forester] recently toured the site and thought I should ask your help with some questions concerning my invasive species practice (beech brush).  This Spring I cut a stand of beech trees to use as fire wood. I sprayed the stumps with Round up and within weeks  the surrounding beech brush died.  This Fall I cut several beech trees and treated the stumps , which were cut higher than the ones in the Spring, with an herbicide containing 44.9 %  potassium salt of glyphosate ( a concentrated generic Round up). I diluted this to make a 0.9% solution.  It has been about 3 weeks and the surrounding brush is unchanged.Could the cause of this be:

 1-  the glyphosate solution is too weak

 2-  the Fall is the wrong time of year to spray the stumps

 3- the beech stumps were cut too high so there was less herbicide penetration.

 I would appreciate your input .

My Response

First, I assume you treated the stumps right away (within a few minutes) or not more than 72 hours after cutting.  Fall is the best time of year to use the cut-stump method on beech.  Spring is usually poor, so all other things being equal, the fall treatment should have provided a better response...more dead beech suckers.  I would usually see changes in the foliage within 2 weeks and full browning of the foliage within 4 weeks.  Late October might be a difficult time to notice an effect as the leaves are starting to naturally brown.  If the root suckers are brittle or lack green tissue if you scrap the bark away, the stems may be dead but not show a foliar response.

Assuming the treatment didn't work, there are three possible answers.  The most likely, if your email is correct, is the dilution to 0.9% active ingredient.  Is that correct?  I dilution from 44.9% to 0.9% would be about two ounces of concentrate to 4 quarts of water.  That dilution is weaker than any I have ever tried for cut stump, and is weaker than what is typically applied as a foliar treatment.  Foliar treatments usually use the weakest solution.  Most cut-stump treatments would have at least a 25% active ingredient.

High stumps might make a difference, but I haven't test that. I wouldn't expect an effect, but there might be if the stumps were especially tall, say 3 to 4 feet.  Even so, I would expect some control of root suckers.  

The final possible answer, though not likely, is that the area may have a high percentage of seed origin seedlings and saplings.  If the seedlings and saplings are not part of a root system connected to the stump you treat, there will not be an effect.

The next obvious question is what can you do.  If your first and my first explanation is correct, the stumps may be "dead" and thus efforts to resurface or drill won't provide access to the fresh wood needed to connect to the suckers.  You could try to re-cut the stumps as close to the ground as possible.  If the wood looks white and fresh you might be able to retreat.  If there are larger stems, say 3 to 6 inches diameter, you could also cut and treat those.  The effectiveness of cut-stump depends on the amount of fresh wood that is essentially a sponge that feeds the root system.  The more fresh wood you treat the better the effect. If resurfacing results in dull colored wood upon exposure, the wood is not likely to conduct glyphosate.  You could try, but I wouldn't be optimistic.  As such, I would cut-stump as many of the sapling or pole sized trees as you can (more is better) and some translocation to smaller stems will occur.  Allow this treatment to work for a few weeks, and then assess how much more you need to treat.  Subsequently you will need to basal bark, cut-stump or foliar spray all the remaining stems.  For basal bark use Pathfinder II, for cut stump use glyphosate at 25% or higher, and for foliar use glyphosate at about 2% active ingredient.  You could do the cut-stump treatments until the wood freezes and the foliar next year. 

I'm sorry I don't have a better message to share.  Please keep me posted and certainly let me know if you have more questions.  If you provide details as you work through the system I may be able to offer a refined prescriptions.

Good luck,


Basal bark of beech.  Pathfinder II is a premix of Garlon 4 and oil...ready to use.

Cut stump treatments can be very effective at controlling beech root suckers.  Be sure to have a plan for how to revegetate the site after the beech is cut and there is an excess of sunlight.

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I think, Peter, that you covered it all.

I once tried to get away with a lower % active ingredient of Roundup for foliage spraying (1.5%) and was unhappy with the results.  Some yellowing, some dead but the following year it was obvious that it was a wasted effort and, re-treating was needed.  [This was on Beech suckers a year after the larger Beech stems were cut.  I did notice good kill of the herbaceous spp. but they were not the problem.]

Hi Mark:

Thanks, this is helpful to know.  I have sprayed foliar at 6% in very heavy beech and had to retreat because foliar density prevented effective penetration of the mist into the subcanopy.

I've experimented with different concentrations of glyphosate when doing cut stump treatments on Buckthorn. I tried the typical "hardware store" concentrate of about 18% glyphosate, on stumps cut in the late summer and fall, treating the stumps within minutes of cutting the tree. The results were mediocre - I had a fair number of stumps that sprouted (I'm guessing 25% of them??)

As Peter mentioned, using at least a 25% concentration works much better. When I tried 33%, I had essentially 100% mortality. These days, I just wait for Tractor Supply or some other place to put it on sale and buy their 41% generic concentrate. If I get it on sale, it's cheap enough that I just use it at the full 41% concentration rather than messing with diluting it.

BTW... when cutting larger trees, it's not necessary to coat the entire stump. just cover a ring around the outside edge of the cut surface. (I'm guessing the trick is to just cover the cambium layer?)

I have had an inclination that European buckthorn is one of the hardest species to kill. John is adding fuel to that fire.  A flame weeding project (no pun intended) a few years ago resulted in considerable resprouting below the flamed girdle 12 months post-flaming.  The cooperator said that most of the sprouts died later.

Most of the glyphosate labels I've seen indicate the outer 2 inches of cut-stumps should be treated.  I don't know if that is for vascular cambium.  Glyphosate interrupts the development of an enzyme necessary for photosynthesis.  We'll need an eco-toxicology-physiologist to explain how a stump without leaves and no ability to photosynthesize is killed by glyphosate...but it works.

Peter; I believe that glyphosate inhibits growth by interrupting amino acid development and not directly acting to interrupt photosynthesis. Although those amino acids are needed for that too, other growth in general is inhibited at the woody growth sites so... I could be way off but I think this explains the effectiveness on cut vascular tissue. (I see you didn't get a response from an eco-toxicology-physiologist so ...will a Forester do?)

would a small goat heard or hogs be of help here? A solar fencer and and some fence tape to keep them in place.

There was a research project on that. You can see it here:  http://www2.dnr.cornell.edu/ext/goatsinthewoods/About_the_project/w...



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