By burn I meant it will kill the top growth to the ground. It will look dead, but the roots are just fine.
Which makes me wonder if it wouldn’t be advantageous to incorporate a soluble nitrogen fertilizer with the glyphosate …
Farmers/co ops almost always add ammonium sulfate when spraying gly
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Yeah, all my best ideas were stolen before I got to them!!
Hmm, glyphosate is a systemic herbicide; it is also absorbed into the roots and kills from there. I have used it successfully on black locust and Japanese knotweed.
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Has anybody tried high concentration vinegar for spot control of weeds such as thistle. In high concentrations its supposed to be like a corossive acid that burns vegatation out. I ask because it’s completely natural, and after a few rains I’m sure it will wash away without harming other plants or contaminating the soil.
Vinegar will kill the top growth of many perennial and annual weeds, but it does nothing to the roots.
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Just to be clear, I’m not talking about household vinegar. Where I live in Canada, we have restrictions on shipping any higher than 75% concentrations, (but I can get 75% vinegar shipped to me). I was hoping the concentrated stuff might actually kill down to the roots.
Not much good for a farmer with acreage, but for small scale home usage it seems a good alternative if it works. Pesticides are very hard to obtain in Canada, (at least in BC). We can’t even buy surround in Canada.
Sounds like your Canada thistle acts a lot like bindweed here. Glyphosate will kill all the top growth over a week or so, but then it comes back up. But with bindweed, when it comes up the second time, it’s very weak. If you can get it sprayed again, before it regains strength, you can generally kill it, or at least significantly thin it out.
Canada thistle is a big yawn’r here. It’s not invasive at all here. I don’t even bother spraying the occasional plant I see the fence rows. Perhaps it doesn’t like our heat? Musk thistle is a big deal. Musk thistle will take over whole pastures in our area.
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I generally ignore most Canada thistle. Where I do fight it is in foodplots and in my wildflower plot.
If a person does a web search for “controlling Canada thistle” you’ll find a great number of state dept. of agriculture results as well as university ag depts results. It’s difficult to control in many areas.
The same can be said for Musk, Plume, and Bull thistle.
All cause me more problems than Canada thistle too. However, all of them are much easier to control with a single shot of herbicide.
I agree that Canada thistle may be controlled with repeated applications of gly to new growth. You need to exhaust the roots/rhizome’s energy source.
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For broadleaf Aim/Antik is another safeish option. It’s just a burn down, but if you hit any big weeds with Glyphosate when the trees are dormant and stay on top of things it will take care of any broadleaf that escape any pre emergent. It’s also labeled for sucker control on most fruit trees, persimmon is on the label, but jujube is not.
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I add a little Miracle Gro to my glyphosate.
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Vinegar might be natural, but at 75%, it’s highly corrosive and can cause permanent blindness if you get it in your eyes. In my opinion, the short-term risk is more than a little excessive for something that still won’t kill weed roots.
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I know it’s corrosive, I wasn’t planning on rinsing my face with it. 
I live on a lake used as the source for most of the residential drinking water in my area. I try to use as as little chemicals/pesticides as possible. I also live in Canada where many of the pesticides commonly available in the US are not permitted to be sold to home growers.
Can you get Capric acid based herbicides? A lot safer and I find it to be more effective.
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Thank you for that info @Evenfall, I’ve never heard of capric acid before. I’ll see if I can locate some.
Well it’s been about a month and a half since I first applied 75% vinegar to some Canada thistle in my yard. No sign of life from the scorched remains. I think I can safely say by now that it killed them down to the roots.
Have you tried hitting those caterpillars with it?
I don’t think I’d want to get any spray drift back onto me from the wind as it would likely peel my skin off. 
Well that’s a valid point. I guess I was thinking spray from upwind and or elevated position. Like across the the fence where they are deploying from.