August is the traditional time to prune apricot trees in the Northern Sacramento Valley, California because this usually gives the tree six weeks of dry weather for the pruning wounds to heal. When open cuts on apricot limbs get wet, the tree is susceptible to Eutypa fungus. Remove about 20% of last year's growth. Remove broken and diseased branches.
It is also a good time to think about trimming those young Cherry trees (first 5 years) too, which too can suffer from bacterial infection.
Here are two excellent papers on pruning fruit trees: