Cladoptosis is the naturally occurring shedding of branches of a tree. The tree may do this as a reaction to drought, soil compaction or disease. The branch that comes off will have a rounded ball and socket look. Specialized cells form where a break occurs. This is a protective layer that minimizes moisture loss. This will tell you that the tree is self pruning and not a large concern but to reduce the amount of limb drop increase watering and fertilization and reduce soil compaction in root area. Larches, pines, poplars, willows, maples, walnut, ashes, bald cypress, and oaks, shedding of branches is normal, often occurring annually in the fall, similar to the shedding of leaves from deciduous trees.
If the branch does not have this smooth looking break inspect the tree for visible defects and signs of insects. You should seek and arborist as soon as possible as other branches may come down. Different species are susceptible to various diseases and insects so professional advise is key in the correct treatment. Summer branch drop is common in older trees and in species such as oak, elm and ash. Correctly trimming a tree can prevent this hazard. Prune out damaged and low growth branches and those with decay or cavities. On mature trees have the long horizontal branches lightened and shortened and thin out the canopy.
If your tree has invasive rotting at the base of the tree it is called “butt rot”. The trunk of the tree is like the stem on a flower. If the stem gets broken it is not good. This condition may occur without you even noticing. There might be a shelf of fruiting bodies or mushrooms which you didn’t realize can indicate this problem. Unfortunately there is nothing you can once this is discovered as it has probably has been harming the tree for years, wood decay works from the inside out. Cutting the rotten wood out leaves the tree more vulnerable to disease because the tree can’t heal damaged tissue they will try seal them off and continue to grow. Painting the tree with wound dressing does not close wounds. A certified arborist could be called to see how extensive the damage is. If the tree is at risk of falling on a house or on people it may need to be removed.
If the tree is stable it would be good properly fertilize,water and prune the tree. A healthy tree could heal over the wound as it naturally grows new wood.Try to protect the tree from further damage. Lawn mowers or other vehicles may have damaged the tree. You can put mulch and maybe a rock ring in a large area around the tree and keep out other competing plants and grasses that need to be trimmed or weed-whacked. The tree can be wounded with the mower blade or string and this is where pathogen can invade.