Jul 15, 2019 - 04:00 AM
Opened bottles may only last 1-2 years. The rule of thumb on any pesticide - since they don't contain expiration dates - is to use them according to label directions regardless of the age. If at that time, they do not work, then use new pesticide.
Pesticides are like pharmaceuticals, some may last a very long time. We just don't know exactly how long.