According to Texas A&M AgriLife Extension, too much water is as damaging to plants as too little, especially if the flooding persists for more than 2 or 3 days. Roots require abundant oxygen to live and grow, and waterlogged soils become anaerobic quickly. Waterlogged plants are stunted and often exhibit nutritional deficiencies because of poor root absorption. Waterlogged plants are also predisposed to root diseases.
Although the impact of flooding on homes and other structures is almost immediate, the effect of flooding on trees is not as immediate in most instances. Over the past few days, I received many calls asking about how flooded landscapes will impact the health of trees. There are several factors to take into account when considering the impact of flood stress on a particular tree. These include: 1) duration of flood, 2) species tolerance to flooding, 3) age of tree, 4) tree vigor, 5) season, 6) water temperature and oxygen level, and 7) freshwater vs. brackish water. The longer tree roots are exposed to flooding, the greater the potential for injury.
The good news is that short periods of flooding during the growing season can be tolerated by most trees. In fact, with the exception of pines, most trees can withstand 24-to-36 hours of flooding without any long-term problems. However, if flooding is recurrent and keeps the soil saturated or prevents recovery from previous floodings, injuries will accumulate and serious damage may occur. Even so, it is strongly recommend allowing 6-to-8 weeks time before removing a tree to provide sufficient time to better gauge the damage sustained and the likelihood of recovery. An important exception to this recommendation involves large trees that are not solidly anchored, or otherwise pose a hazard to home, traffic, play grounds, etc. For those with a measure of patience, it is suggested to wait for spring for the tree to show its progress: Does it have a full complement of leaves? Do the leaves have an overall green as opposed to green with brown-tips? As can be seen, determining the flood tolerance of a species of tree and the actual impact of a flood on trees in a given area are influenced by a complicated and diverse set of factors. How well a tree copes with flooding depends upon how vigorous the tree was prior to flooding and how long the flooding occurs. Well-maintained, healthy trees can and usually recover quickly when flooding is relatively short in duration and flood waters. For more information please contact the Hopkins County Extension office at 903-885-3443.
Article by Dr. Mario A. Villarino, County Extension Agent for Agriculture and Natural Resources in Hopkins County, Texas.