The primary effect of flooding is the reduction of oxygen in the soil. Most of the fine roots of the tree are in the upper six inches of soil; these roots are responsible for the uptake of water and oxygen. As oxygen levels decrease, the fine roots begin to die. As the roots die, the tree’s ability to absorb water decreases and the foliage begins to wilt.
It may take several years for a mature tree to recover from a summer of flooding. The trees will be vulnerable to attack by pests and pathogens. You should inspect your trees on a regular basis to identify and manage any disease outbreak. During this time you should not fertilize the trees or prune any living branches from the crown unless they are broken. Dead branches should be removed.
As the soils dry, you may need to water your tree. Much of the root systems will have been damaged and your tree may not have a sufficient number of roots left to absorb the necessary amounts of water to sustain itself.
The most common symptoms associated with flooding are:
- Leaf discoloration, usually yellowing
- Leaf scorching and wilting
- Premature fall color
- Premature defoliation
- Sprouting along the trunk
- Twig and branch dieback
- With severe or persistent flooding, death
These symptoms may occur during or after flooding: