On Tuesday, July 28, 2015 at 12:38:55 PM UTC-4, dpb wrote:
On 07/28/2015 10:04 AM, (PeteCresswell) wrote:
It's been about five days since I first sprayed some poison ivy with
Roundup - with a touch up application yesterday.

I'm not seeing any signs of distress in the stuff.
...
Bottom Line: Should Roundup be effective against poison ivy?
...

If you got a 2% solution on the leaves and it was/is actively growing,
glyphosate should work but by itself it isn't as effective as some other
combinatorics...

http://www.clemson.edu/extension/hgic/pests/weeds/hgic2307.html

The guy talking about using concentrate is mostly wrong, btw...the
concentrates are all intended to be diluted before use; the only part he
got right is "read the label".

--

I don't know about 2%, I typically mix it at about 4% and it kills
poison ivy. Since Pete is having a problem, I'd mix it at 4%+.
If you read the directions, to kill tougher weeds, they call for
higher concentrations, up to about 6% I think.

If you're using the stuff, you can get the ~48% concentrate for about
$65 for a 2.5 gallon jug. That's orders of magnitude better than
buying it pre-mixed or even the concentrate at HD, etc. That's for
the generic glyphosate with a sticking additive included.

There are also brush killers that are more effective against that
type of stuff too.