my sugar maple is having leaves starting to be absent on the tallest limbs at...
my sugar maple is having leaves starting to be absent on the tallest limbs at top of tree...the tree is around 40 feet tall, 25 years old...up til this year, has been very good an healthy, is by itself in corner of my yard, my other large sugar maple is in other side of my large yard an no sign of same thing...
Wapello County Iowa
Thanks for contacting eXtension with this question. There is not an easy answer or easy solution to this situation, unfortunately. Researchers have been studying maple decline for some time, but have not come up with wonderful solutions...
The primary suspect for this maple decline/tip dieback would be the drought that your area of the state has experienced for the past several years. One tree can be showing decline while an adjacent tree is unaffected (see the Utah publication for a picture).
As a reminder, even though your two trees are sugar maples, the genetic composition of the trees could be different enough so that one tree can better handle weather stresses compared to the other.
In addition, there may be site differences - more southerly exposure, shade, water drainage, soil compaction, actual soil make-up - which can affect the trees.
Supplemental watering of the tree (as described in the linked references) may help. The effects won't be seen immediately. Next year's buds are already set, so watering (or rainfall) will help keep the moisture content in the twigs, buds, and other wood in a good state.
I would not fertilize until the spring of 2015, as this chemical 'stimulation' will not help your tree prepare for winter this year.
Here are a few references for you to consider: