Diseased Vine Maple
Hello, Thank you for using Ask an Expert, and for attaching an image with your question.
It appears that the majority of the damage is on the back side of the tree. But I’m unable to determine if the damage is limited to one of the major branches or if it also affects additional smaller branches. The fact that the brown leaves are clinging to the branches indicates that death was sudden.
Several possibilities must be explored: Mechanical damage and a disease. The reason I suggest mechanical damage is that the tree appears to be close to the house. If so, perhaps branches were cracked or broken during repairs, painting the house, and/or children or large pets. To check that, look closely for a wound, crack, or twisted branch at the base of the affected part.
Verticillium wilt, a soil-borne fungal disease, is also possible. If so, the tree will eventually die. To check for the disease, sever one of the recently failed branches that are at least a half inch or so in diameter. Look for a stain just underneath the bark; the stain may be an entire circle or partial. You can see examples at these sites: http://www.fs.fed.us/r8/foresthealth/idotis/diseases/vertwilt.html http://www.forestryimages.org/browse/detail.cfm?imgnum=5037027
If the problem is Verticillium, the only possible treatment is to remove the dead parts as they occur. Eventually the tree will look so bad you’ll want to remove it. When you decide to plant in the same place, please refer to “Plants Resistant or Susceptible to Verticillium Wilt” at http://pnwhandbooks.org/plantdisease/node/1812/print
Or, to obtain a first-hand opinion about your maple, contact one or more Certified Arborists for an onsite evaluation. You can locate Certified Arborists in the Yellow Pages, online or in a phone book. Companies with such a person will include that information in their ads, either as a brief statement or as a small rectangular logo stating “Certified Arborist.” When you contact each company, avoid any unwelcome surprises by asking if they have a fee for the visit and evaluation.