Flooding From a Tree’s Perspective

While flood waters are in and surrounding your home, it’s best to focus on the basic needs of life – food, water and shelter.  After initial needs are met, those of us with medium to large trees should consider the influences of an extended period of time with excessive water in contact with the roots, trunk and base.


In short, these tissues are not designed to be submerged for a long period of time.  Other than a few species, most of our tree resources will suffer extensively.  It’s common to observe the following:


*Softening of root, trunk and basal tissues.  These tissues often cease to function normally, causing severe stress on the tree.


*Leaning trees.  Once the roots soften and loose connection with soil particles, trees often follow the path of least resistance in the soil and lean.  If the new direction of orientation is towards a house, shed, car, patio, deck, etc., contact an ISA or NAA Certified Arborist for removal.


-ISA – https://www.isa-arbor.com/For-the-Public

-NAA – http://nearborists.org/


*Aerial rootlets.  Certain species that are adapted to submersion (cottonwood, sycamore, baldcypress, willow, swamp white oak) begin to grow roots on trunk and branch tissues.  This is not a big concern, just an adaptive response to flood.



In response, consider these corrective actions:


*Pull the mulch and any accumulated debris away from the tree trunk and don’t put it back until the soil has changed from muddy to moist.  Use 2 inches of wood chips to keep the soil moist, not soggy or dry.


*Hire an ISA or NAA Certified Arborist to remove broken branches.


*Watch out of secondary pests such as cankers, spider mites and aphids that take advantage of a stressed tree.


*Do not fertilize the tree for at least a year.  Trees under flood stress need 1-3 years to reestablish damaged roots; fertilizer often interferes with root regeneration.


*Be patient; it could take several years for the full effects of the flood to be seen.

John Fech
Horticulture Extension Educator at Nebraska Extension
John Fech is a horticulturist with the University of Nebraska-Lincoln and certified arborist with the International Society of Arboriculture. The author of 2 books and over 200 popular and trade journal articles, he focuses his time on teaching effective landscape maintenance techniques, water conservation, diagnosing turf and ornamental problems and encouraging effective bilingual communication in the green industry. He works extensively with the media to extend the message of landscape sustainability, making over 100 television and radio appearances each year.
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