Dan_Musicant wrote:
I have a dwarf peach tree that's had perrenial peach leaf curl. More
than 20 years ago I bought a plastic 1 pint bottle of Chacon Bordoil
Copper-Oil-Fungicide, but have never even opened the bottle. Under
Active Ingredients it says:

Copper Sulfate (anhydrous) 6.4%
Petroleum Oil 30%
Inert Ingredients 63.6%

There are warnings about poisoning the water supply and appropriate
precautions. This dwarf tree, which was severely ravaged by peach leaf
curl this last spring/summer is right next to my compost pile, which I
use exclusively to fertilize my vegetable crops - tomatoes and squash.

The unused and unopened bottle is plastic, and for some reason it's
become deformed. It looks as though the volume has shrunk as the walls
of the bottle are pulled in on 3 sides (i.e. the cross section is rather
triangular. I have no idea why.

Should I be concerned about contamination of my home grown produce by
virtue of using this (or another) means of stopping the peach leaf curl?

You can look up toxicity of copper sulfate, but, I don't think it is
something to worry about. Pure material may be toxic but by time it
gets diluted in run-off, it should not be a problem.
Plastic is not impermiable and some of contents have probably
evaporated through the plastic and there may be some oxidation of the
oil or intert contents as well as moisture intrusion. If not
separated, this should not be a problem. For long term storage, glass
or metal containers are far superior to plastic.

In my limited experience with peach trees, their lifetime is short and
it may be better to replace the tree.

Frank