Julianne Mason on “Basal Bark Applications Using an Oil-Water Emulsion”

Editors note:  At our recent GRN Workshop in Kane County I announced I was looking for guests to write posts for this blog.  Juli Mason was in the audience and below she gives us a helpful  report.  If you have an topic  you want to share contact me and I or someone with the GRN will work with you to post it here.    

Also, I am reposting this one because it seemed to not email out the first time.

Juli - head shot

Photo above and text by Juli Mason:

Fall is a lovely time here in northeastern Illinois.  The leaves are turning, mornings are crisp, and invasive shrubs stick out like sore, green thumbs against the senescing native vegetation.  Previously, Bill Kleiman has posted articles extolling the virtues of using basal bark application of herbicide as an efficient and effective method to kill bush honeysuckles. He used 17% Garlon 4 in bark oil.

I have also found that treatment to be effective, but have noticed that the oil kills all plants in the overspray zone.  This usually isn’t too egregious as long as you keep the sprayer pressure low to minimize overspray.  The space fills back in with the surrounding vegetation within a year or so.  However, there have been a couple of cases when it rained within a day after the basal bark application or it was done over snow cover and the oil washed down slope, leaving a zone of death heading down the hillside.  Guess it takes oil a while to “dry”.

Caption:  Basal bark treatments are an effective way to kill invasive shrubs, but all plants (grasses and forbs) are killed in the overspray zone.

In the fall of 2017, my coworker, Nick Budde, and I treated various invasive shrubs with different concentrations of herbicide in oil-water emulsions, to see what lower concentrations might be effective at killing the shrubs while reducing the cost of the treatment.  We were also curious if reducing the amount of oil might reduce the collateral damage caused by the oil overspray.  In addition, we have been wondering if it’s really important to get a full 360 degree application, since it is a lot faster to not walk all the way around each shrub.

For each of the herbicide combinations, we treated half of the shrubs with a 360 degree application, walking around the entire plant and basal treating the whole stem circumference.  For the other half of the shrubs, we treated them by standing in one spot, and reaching our spray wands around to spray all sides as well as possible without moving our feet.  Being a former contractor, I refer to this method as “contractor-style”, but you can also think of it as an efficient application style.  Regardless of application style, we sprayed the base to a height of 3-4 inches for smaller shrubs (<6’ tall or so).  For larger, tree-like shrubs, we were more diligent about spraying the base to a height of 8-12”, like it says to do on the herbicide label.  Most of the shrubs that we treated were non-native honeysuckles and multiflora rose, although there was a smattering of other invasives, including common buckthorn, winged euonymus, autumn olive, and Japanese barberry.  We marked each treated shrub with a ribbon that was color-coded to the treatment type and application style.

Caption:  Area where the invasive shrubs were basal bark treated in the fall of 2017, viewed one year later.  Each treated shrub was marked with a ribbon that was color-coded to the treatment type.

Here were the treatment types.  We used Relegate herbicide, which has the same active ingredient as Garlon 4 (ester formulation of triclopyr).  The label recommends adding an emulsifier for oil-water emulsions, but we didn’t have an emulsifier so we didn’t add one.  We just shook the herbicide mix back and forth in the sprayer tank for 30 seconds.  We didn’t agitate it in particular after that, just walked around and sprayed.  It does separate if it sits in a jug, but re-suspends into an emulsion again when agitated.  There were roughly 60-100 shrubs in each treatment.

20% Relegate + 80% bark oil

20% Relegate + 20% bark oil + 60% water + dye

10% Relegate + 20% bark oil + 70% water + dye

5% Relegate + 20% bark oil + 75% water + dye

When we checked on our plots this past spring (6 MAT), we saw that the treatments had worked for the multiflora roses.  Nearly all of the roses were dead regardless of treatment type or application style.  This included some monster roses (8’ tall and 10’ diameter).  This is great news for anyone who needs to treat multiflora rose, since trying to walk through a rose patch stinks.  Handling rose canes to use a cut stump method stinks.   Foliar treating those rambling canes results in a lot of overspray.  Also, I’ve noticed that roses tend to re-sprout after foliar treatments, so foliar sprays often are not effective.  It is nice to be able to just stick your wand strategically into a thorny mess and spray the canes at the base.  The ones that were not dead were the canes that were missed.  When we checked the plots this fall (1 YAT), all of the treated multiflora roses had completely died for all treatment types and application styles.

Caption:  All of the multiflora roses that were basal bark treated died, even the ones that were treated with only 5% Relegate emulsion and treated while standing in one place without walking around the entire plant.

In contrast to the roses, most of the honeysuckles and other invasive shrubs leafed out in the spring after treatment, although they looked somewhat stressed.  However, when we checked the plots this fall (1 YAT), nearly all of the honeysuckles and others had died in all of the treatments that had at least 10% Relegate, regardless of application style.  The only one that did not die was a 10’ tall honeysuckle that was treated “contractor-style” with the 10% Relegate emulsion.  Less than half of the honeysuckles treated with the 5% Relegate emulsion were still alive.

Caption:  About half of the honeysuckles that had been basal bark treated with herbicide in the fall of 2017 leafed out the following spring.  With a proper application style, all of the ones treated with at least 10% Relegate emulsion eventually died, but it took nearly a full year for some of them.

We repeated the treatment types and application styles in the spring of 2018, to see if treatment timing matters.  When we checked on our plots this fall (6 MAT), nearly all of the roses were dead regardless of treatment type or application style.  Nearly all of the honeysuckles and other shrubs were dead that were treated with a 360 degree application with at least 10% Relegate.  Less than half of the ones that were treated contractor-style with an emulsion with at least 10% Relegate were still alive.   More honeysuckles that were treated with only 5% Relegate were still alive than those treated with a higher concentration of herbicide.  It will be interesting to see how many of those still alive succumb to death in time – we’ll check them in the spring for a final verdict.

Caption:  Some honeysuckles that were basal bark treated in the spring of 2018 are still alive the following fall.  Have they shaken off the herbicide application, or are they on a very slow road to death?  Only time will tell.

As a general observation, there were still dead zones from the overspray of the oil-water emulsions for both the fall and spring treatments, although it seemed to be a little more diffuse than with the straight oil basal bark treatments.  There were scattered sprigs of herbaceous plants that were not killed by the overspray in the emulsion treatments.  I’m interested to reduce the amount of oil in the emulsions even further to 15% or 10% and see if those treatments are still effective.

What I’ve learned:

  1. Using a contractor-style basal bark treatment to kill multiflora rose is wonderful!
  2. Oil-water emulsions work for basal bark treatments, and they are cheaper and put less chemical in the environment than straight bark oil.
  3. Walking all the way around the shrub to get a 360 degree application is important for bigger shrubs (>10’ tall), but does not appear necessary for smaller ones.
  4. It sometimes took a full year for the shrubs to die, so be patient. With a proper application style, all of the ones basal bark treated with at least 10% Relegate succumbed to death.

Note: special thanks to Phil Solatka with Archer Pines Landscaping for giving me the idea to try oil-water emulsions for basal bark treatments.

Julianne Mason is the Restoration Program Coordinator with the Forest Preserve District of Will County

Caption:  Another dead invasive multiflora rose from the basal bark treatment.  

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8 Responses to Julianne Mason on “Basal Bark Applications Using an Oil-Water Emulsion”

  1. Ruml, Cameron says:

    Did you see this? We should try a similar method for buckthorn.

    • Bill Kleiman says:

      Cameron: Did you receive the blogpost by Juli on basal bark via email? Some did not receive an email and I trying to figure out what happened. Yes, these methods should work well on buckthorn and autumn olive too.

  2. James McGee says:

    This method would put less crop oil into the environment while spraying. However, where I have volunteered we are not permitted to spray. If herbicide was being applied by paint roller then I would think having a higher concentration of active ingredient and applying a proportionally reduced amount of mixture would be the best way to also reduce the amount of crop oil needed (although this probably would not be allowed either).

    The invasive woody species control I have help do or observed is mostly done during winter. I would be curious to know the results of using this, or Bill’s, method during winter. Of course, an emulsion probably would not work when the temperature is below freezing. Cut stump application is often what public agencies mandate in Cook County. Being able to apply herbicide below freezing is the main advantage of using an oil based herbicide if what you have been limited to is cut stump application.

    • Bill Kleiman says:

      Bill Kleiman here: Thanks for comments, James. The study I did a few years back was in May and we got 100% kill with 17% basal bark on honeysuckle. Recently, Kaleb Baker of NIU is doing a similar study but in the fall, winter and spring. Before working up all his data, he reports that he got very good control in all seasons.

      • James McGee says:

        Kaleb Baker getting good results applying triclopyr ester on the basal bark of Asian Honeysuckles makes me wonder what people in my area have been doing wrong. People have been applying triclopyr ester to the cut stump and a few inches down the stem. I have not observed any success on Asian honeysuckle although buckthorn is typically killed. I wonder if people are not putting on enough herbicide for Asian honeysuckle control. In contrast, when I have frilled tree like honeysuckles and put 41 % glyphosate in the cut, all the shrubs I have treated have been killed. I have also had success with 41 % glyphosate on cut stumps if enough is applied. I think painting it on once isn’t enough. I plan on trialing painting it on thick twice and giving it time to absorb into the stump in between coats. I am hoping applying the herbicide twice with give a high percentage of control (95 % or more).

  3. Bill Kleiman says:

    In natural areas management we need more controlled studies on these common brush control practices. This is why I like the Grassland Restoration Network because we can share best practices and best science as it comes in. I would have told you that garlon4 oil on cut honeysuckle stumps give 100% control. I have done that treatment, and marked each stump with tree marking paint to verify months later that my treatment worked. We did not publish that data because the sample size was small. We do have a paper coming out on basal bark on honeysuckle, uncut, and we had 100% kill on all size shrubs with a May application. – BK

    • James McGee says:

      People’s attempts to use the minimum necessary amount of herbicide has come with the cost of doing rework when control is poor. I have seen a lot of people apply too little herbicide and get poor (or very poor) control. Often, follow up is not done which leaves the site in a worse situation than before the control effort had occurred. Bill is probably getting good results because he applies the herbicide thickly, whereas other people are not getting decent control because the herbicide is applied thinly. We need to quantify the size of the invasive species, the amount of herbicide being applied to each individual, and the resulting successes and failures. This will give organizations the information they need to train herbicide applicators to accurately estimate the amount of herbicide that needs to be applied to get good control while not unnecessarily using too much.

  4. James McGee says:

    The honeysuckles that appear to have “shaken off” the herbicide application were likely sprayed with mostly just water. Oil floats in water and emulsions can break very quickly. Try making the herbicide emulsion and putting it in a clear container so you can see the speed of separation. Some honeysuckles probably got mostly water and others got mostly oil and herbicide mixture.

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