Certified GKH Gardening Expert
Native mulberries are tough plants and usually survive attacks by disease and insects. Check the existing leaves for signs of disease or insects and consult with your local extension agent if you find cause for concern in the healthy foliage.
You can prune out the dead wood or hire an arborist to do so.
Does your tree get plenty of sun? Mulberries prefer full sun to light shade.
Is anyone walking across the shallow roots? Root damage can cause issues above ground. You can mulch under the tree to the dripline to help protect them.
Is your tree getting adequate water? Once established, mulberries are drought tolerant, but perhaps your area has experienced excessive dryness.
Mulberries don't normally require fertilizer.
Here is more information on general care of mulberries that might help: