On Tue, 28 Jul 2015 11:04:58 -0400, "(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.

OTOH, 3 days on crab grass and the stuff is clearly dead or on the way.

Bottom Line: Should Roundup be effective against poison ivy?

If so, what timeframe?
Roundup alone is not terribly effective on poison ivy because of the
oiliness of the leaves. You need a good surfactant mixed with the
roundup. Some people use a bit of dish soap in the mix - some a few
tablespoons of diesel fuel. I know the diesel fuel works. Generally
knocks it back pretty good in about 3 or 4 days.