If the tree is dormant, you should be able to spray copper and dormant oil together. Check with the manufacturer of your copper spray concentrate.

Here, where peach leaf curl is a bigger risk than in Phoenix, the recommended schedule for copper/dormant oil spraying is:

Thanksgiving week
Christmas week
Superbowl week

I've been in Phoenix at Thanksgiving, and you typically have nicer weather than we usually have here at that time. Your spray schedule may be different from that above.

If you think that the problem is heat stress, consider painting or re-painting the trunk and big branches with cheap white interior latex paint, diluted by half with water, next spring.

Hope this helps.

Carol are you talking 3 seperate sprays or choosing one of those dates? Seems awful close together for three seperate sprays, but then I'm a few hundred miles north of Phoenix.
dan

I doubt that three sprays would be necessary in the deserts of Arizona. I am in the foggy-winter Central Valley of California. As I understand it, the first copper spray is especially important for peach leaf curl. The other sprays control brown rot and other diseases. For some stone fruits an additional spray of copper or another fungicide is recommended nearer to blossom time, especially in humid weather.

I would recommend checking with your extension agent or another knowledgeable person in your area for spray schedules for disease and insects.