"Koi-minator" invalid@invalid wrote:

Roundup does work on poison ivy. I have been using it for many years.
You need to use a strong mixture and add a spreader/sticker and may need
to reapply. Roundup works best on mature plants that are sending sap to
the roots, since it works by killing the roots. On very tall vines of
poison ivy, cut the ivy off about chest high and spray the lower part.
Poison ivy spreads by the rhizomatous roots and the seeds which birds
spread in their guano.

## And that's how we believe it keeps showing up on our property. :-( We
used RoundUp at 6 oz. per gallon and had about a 50% killrate for poison ivy
in the past.

I use Roundup at a rate of 4 oz per gallon and get 99% kill rate. I am
spraying new seedlings that have small roots. If you are spraying a
field with established rhizomes, then you will need to keep at it since
the rhizomes can extend many feet under ground. Unless you spray every
green leaf that comes out of the rhizome (which may extend over acres),
you won't effect a kill. If you cut a trench round the kill area about
a food deep, it will sever the rhizome around your kill area so you can
get a complete kill. If you plow a field of rhizomes, every piece will
form a new plant.

In large areas, mowing repeatedly may drain the rhizomes enough so that
spraying will be more effective or not even necessary.
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