In article , Frank J
Warner wrote:

I have about a gallon of premixed Roundup in a two-gallon garden
pressure sprayer that I mixed about six months ago and did not use. It
has been sitting in my garden shed since June.

With the glorious warm weather we're having in SoCal this weekend I
thought I'd hit a few weeds that sprouted during the recent rains, but
I don't know if this six-month-old Roundup is still good. I've read the
package instructions carefully and it says nothing about storing
premixed product. It does say that Roundup becomes inert
("deactivated") when it hits the soil, but nothing about the
effectiveness of leftover mix. I vaguely recall some of the
groundskeepers at work mentioning that mixed Roundup slowly becomes
inert with time, but my memory of those conversations is a bit fuzzy.

It's no biggie to mix up a fresh batch, but as expensive as this stuff
is, I'd like to not waste it if it's still good. I thought I'd ask here
before calling Monsanto.

Frank

Thanks all.

I used the old Roundup. But it ran out fast and I have a large yard, so
I mixed a fresh batch and went over everything with the new mix just to
make sure.

Frank

--
Here's some of my work:
http://www.sharpbywarner.com