Daconil/chlorothalonil is also used for spraying peach trees to prevent peach leaf curl. I now date my bottle when I buy it as it seems to last for 7 years but when I tried some that was 8 years old I had very poor results.

I always hate using this stuff as so thick it is hard to even rinse it off my measuring spoons.

Thanks. I figured as much. Shelf lives are arbitrarily set by the producer partly in order to get people to buy more. I have to assume that the conditions in which it is stored affect shelf life. I have a shed outside that gets up to 110F in the summer. Many pesticides can't take that.