Two very old pecan trees have a large hole indented in the trunk base. There ae several dead branches at the top. We've had severely cold winters and with extended freezes and extremely hot summers in north Florida in the past 2-3 years. We water the yard, but have drought conditions during the summer months and have a deficit in the normal rain levels and have for numerous years. At times high winds, lightning and thunderstorms cause the loss of large limbs. These trees are unevenly weighted with limbs around the trees. Both are in places that if they fell would damage either our house, the neighbors garage or other landscaping trees or shrubs and fencing. Is it possible to repair the holes and strengthen the trees or should they be removed professionally?