Roots not taking up enough water.

You get to figure out why. Start by telling us in the pot or ground? how often and how do you water it?

I have two at the end of a walk. 10 feet apart. one has brown/dead tips like your picture shows, the other does not. Bought at different places 20 years ago. One starts in the spring green and turns crimson (this is Alabama!), the other starts out crimson and turns green late in the summer. The tree that has crimson leaves now looks like your pic. Trees never feed, watered when it rained. Jim

The tree is watered by sprinklers for 10 min. 3 times a week. It is planted in the ground. I have never fertilized it. I know these trees are slow growing, but this one seems to be especially so.

Improper watering - it is very common for JM's to develop leaf spotting or brown edges if they are not getting the right irrigation.

FWIW, automatic irrigation systems are seldom designed to provide adequate watering for established inground plantings. 10 minutes a day is not going to deliver enough water to the correct soil depth for these trees. Rather than the frequent light waterings - of the kind being offered now - opt for less frequent but longer and deeper watering. Depending on your location and weather conditions, once a week to 10 days (in my climate, I'd stretch that to every 10-14 days) for at least 30 to 40 minutes would be far more suitable. You want the water to penetrate down to the full depth of the root system - at least 10-12 inches. That is just not achieved in 10 minutes unless you are gardening in sand.