I was raised in the Lower Rio Grande Valley, Texas where pomegranates go native and produce great fruit, and I now live in Dallas where they are doing quite well and very attractive, though their fruit here is not as robust as in the Valley. Three years ago while potting some agave I tossed pomegranate seed in two agave pots and have a number of strong pomegranates that need their own pots. I do not recall seeing a health or disease problem on any pomegranate plant, but the fruit occasionally shows signs of attack. Check out Texas A&M,
www.tamu.org, for excellent resources.