Q.dogwood branches brittle
Two dogwoods have been in full sun over 15 yrs. This year sections of entire branches have become totally brittle, with leaves turning and falling off. What do we need to do to get our trees healthy?
Yellowing leaves generally indicate a watering issue, combined with breaking or brittle branches it does appear you have some die off of the tree.
Has it been dry? I would add some watering if so. You also can add 2 to 3 inches of hardwood mulch to help retain moisture.
Also look for insect or fungus problems. Neem Oil is good treatment as is works as both an insecticide and fungicide.