Some tips to apply basal bark herbicide:
Be careful applying these mixes in quality vegetation areas. It is not only a brush herbicide, but a broadleaf plant herbicide. It kills forbs!
In nice areas tighten up your application method. You can leave the pressure very low on the pack, and just gently press the trigger to get a minimum of herbicide on the stems. Or use a paint brush or paint sponge and carefully wipe the stems with the mix. You can also cut the shrub and dab on some mix this way, but the cutting is not necessary. You can wire a sponge to the tip of your backpack sprayer wand and then dab or wipe the mix with little dripping and no overspray. Don’t drip herbicide on good plants.
I generally don’t apply basal bark mix on hot days because it volatizes and perhaps harms nearby good plants. In good areas don’t apply unless it is sweater weather or cooler.
Mark some plants with tree marking paint so you can do your own testing. It is fun.
Expect to return to the area several years in a row to treat the ones you missed.
Expect to get some off target kill within 2 to 8 inches of the stems you sprayed, depending on how carefully you sprayed.
While treating honeysuckle also treat the autumn olive, buckthorn, and mesophytic trees like box elder.
Typically, I apply the mix to all the stems and all sides of the stems. When there is thorny brush in the way I don’t worry about getting all the stems treated.
Go after the scattering of shrubs in a field before worrying about the huge thickets.
Wear safety glasses. Folks who wear prescription glass might get side shields for the frames or wear goggles over your glasses.
Bring some paper towels to clean up. Some rubber gloves for when you are filling your pack or fiddling with the pack. Once you have got the pack working good you can go back to your thicker and warmer gloves.
Don’t fill the pack all the way. Halfway is plenty and will last a long time.
Take your time. You are going way faster than those folks cutting the shrubs. You can whistle while you work while they are still back at the shop preparing their chainsaw.
Elsewhere, I describe how to take care of your Birchmeier pack.
This year, we ramped up our basal bark solution on the advice of Rick Schulte of Crop Production Services. We increased the Garlon4 from 17% to 20%. And we add one quart of Vanquish herbicide to each 12.5 Gallons of mix. Others have adopted this mix so I am trying it out.
Future research question. If I basal bark honeysuckle in winter, say January, does an April fire that top kills the stems still kill the root of the shrub? My current sense is yes, but I don’t have the data.
grassland restoration network 
The following scientific paper seems to come to different conclusions. I wonder if this is because the shrubs you are treating have been weakened by mowing or fire.
Click to access gtr_srs101-24.pdf
James, I emailed Ron Rathfon and asked him why he got poor results with this study but great results basal barking on another study he did. He commented back that the snow on the ground and January low temps might have something to do with it. Or some plants might have been missed during the application. I like to use tree mark paint to mark each shrub I treat. Then I know for sure it was treated. I found 100% kill in all size classes.
The plants we treated in our experiment were in a burn unit, but the fire has not been getting through them so fire was not an issue. One plot had mowed honeysuckle from several years back and so had the multiple stems. They also died with treatment.
Herbicide applications of invasive brush characteristically fail in the Chicago Region and require follow up. After reading through the label on Garlon 4 I think one of the reasons for failure is the herbicide is being applied when snow is present. The second reason is people are not applying enough herbicide to stumps. A third factor could be cold. Removal of invasive brush is usually done in winter for various reasons. The ambient temperature is typically much below freezing and snow is frequently present. It would be useful to know if herbicide application effectiveness was impacted by low temperatures.
James: Thanks for commenting. We need more studies on Garlon 4 treatments under various conditions of temperature, ground freeze, and snow. My observation is that cold does not inhibit the chemical from absorbing into the bark. It may be the chemical does not translocate much until certain warm days arrive. Snow should not affect basal bark application unless the snow or ice is on the stem where you are applying. If I find citations I will share them later. I find Garlon 4 on cut stumps always works.
I think what we call failure is often that many plants are not treated and we return to an area and see mixed results and blame the herbicide or technique, when the issue is that we simply missed a bunch of plants that were small and then they grew area are now big. I have shown people areas we basal bark treated honeysuckle and it looks like we got mixed results because there are living HS, but every plant I treated died. I painted each w blue tree marking paint so I know this worked. Get your self some tree paint and do some experimenting.
Could you tell me more about your Garlon4/Vanquish mix? We started using Garlo4/Banvel (salt of dicamba) mix this winter and are having some pretty big issues with separation. I’m assuming it’s the Banvel that is not mixing with the Basal Bark oil and will be doing a jar test using diesel tomorrow, but I would be interested in hearing your thoughts.
Joni, Sorry for my tardy reply. I am new to using Vanquish in our Garlon4 mix, but I can see it mixes in well, keeps the same clarity of solution, and does not separate. Likely, your Banvel does not like your mineral oil carrier. You may want to contact the maker of Banvel and see if they confirm this. You may need an additive to make it go into solution. Some herbicide makers have regional scientists that tend to be helpful. I have added 1% Milestone to Garlon4 in mineral oil and that seemed to mix well with our mineral oil mix. Our current mineral oil carrier is Bark oil red LT by Loveland.
I’m loving this series of blog posts. so useful and practical!
Thanks for commenting as it motivates me to know someone is reading it.
Is garlon 4 mixed with diesel also effective? I have been using it with success on cut stumps. Is this also effective on autumn and multiflora rose? I am in the process of restoring our farm natives.
Thank!
Some might use garlon 4 in diesel, but the recommended product is a basal bark oil. As I understand it, basal bark oil is mineral oil with perhaps a few additives. I used diesel a long time ago and found that it was hard to get the odor out of my clothing. Yes, it works on olive, rose and other broadleaf and woody plants.
Bill,
I think research shows that if one uses diesel fuel then they don’t really need the herbicide. But unfortunately diesel fuels will leave a much longer brown out of surrounding vegetation than does the Garlon 4 and mineral oil
Thank you for the information! My wife and I bought 79 acres in central Illinois and are trying to restore it. I have a Chapin sprayer with viton seals. Will it work for spraying the basal oil with Garlon 4? What would you recommend to clean it with, after use? Is there a temperature range or time of year when basal spraying is not effective? Thanks again!!!