As I clean the house and garage I keep turning up things like Roundup, Weed-B-Gone, Preen, wasp spray, and the like. Some of these might have been sitting there for decades. Is this stuff still good or should I dispose of it?
I have a huge jug of 100% Roundup that has an expiration date of 2000 or so. It still works fine.
Call the manufacturer.
If the stuff is old enough, among other possibilites it may have been pulled off the market for good reason.
And, if you’re going to dispose of such things, bear in mind that most of them aren’t supposed to go in the standard trash. Your area may have an occasional day scheduled for accepting such materials.
It’s going to vary product to product. There are multiple degradation modes.
Any chance the stuff in the garage was frozen. I haven’t had much success with stuff that was.