Dead branches in healthy (?) Garnet

I have a Garnet that seems to be growing vigorously (doubled or tripled in size in 5 years) but every year has a significant number of branches that die. Most of them are lower branches, and in fact their removal has helped the tree's appearance. The tree is on the north side of the house under the drip line, so it doesn't get much direct sun but gets plenty of moisture. Should I worry about the dieback each year, or is this normal?

 

What is the outward process by which you see the branches die? What color are they during the process. What happens to the foliage. How large in calliper are the branches?

When the lowest small branches on a maple die, my first thougth is verticillium. Although maples do self-prune, this is usually limited to very small twigs. When other branches are lost it is usually the compartmentalization of a disease. A healthy maple can easily deal with many pathogens, including verticillium, by dropping a branch or two every year. If they are small and don't detract from the form of the tree, it is no big deal. What you will have to watch out for is if the tree comes under strees or is weakened by another pathogen, then a disease like verticillium can take over. The branch drop due to VW is most often seen, in my experience, in late spring and late summer.

Post a photo if you can.

MJH

 

Some twig dieback is fairly normal among dissectums.
Since you mentioned this is happening primarily with lower branches, I agree that Verticilium Wilt may be the problem.
Low branch dieback may also indicate that the maple is getting too much water (very common in heavy clay soils).

How often, how long, and by what method do you water?
What type of soil do you have? If it's heavy clay, I'd seriously urge you to invest in a moisture meter (they run about $8-10).

'Garnet' can actually tolerate a fair amount of sun (full sun in the San Francisco Bay Area). To hold it's red coloration in the summer, it needs at least a good dose of morning sun - otherwise you may find it "greens up" as summer progresses, particularly on the lower, inner growth.