Title

Helping Flooded Trees and Shrubs

(H1592, Revised April 2021)
File
Summary

Flooding periodically happens in North Dakota. Post-flooding management decisions can help or harm trees and shrubs on their road to recovery. A list of flood-tolerant trees/shrubs, and a list of flood-sensitive trees/shrubs, are provided.

Lead Author
Lead Author:
Joseph Zeleznik, Ph.D., Extension Forester
Availability
Availability:
Web only
Publication Sections
Flooding scene with trees and shrubs submerged
Photo Credit:
Megan Myrdal, NDSU Photo

Symptoms of flood damage

  • Leaves – discoloration (yellowing), wilting, scorched appearance, early fall color or leaf drop (Flood symptoms are very similar to drought symptoms.)
  • Branches – dieback of existing branches, sprouting of new branches from the trunk

Determining amount of damage 

  • Water – If the entire tree crown is or was covered with water for any amount of time, the tree likely will die. However, a high amount of oxygen in the water can reduce the damage:
    • Fast-moving water contains more oxygen than slow-moving water.
    • Shallow water warms quicker and loses more oxygen.
  • Health of the tree – Very young and very old trees are unlikely to survive; previously healthy trees have a better chance at survival.
  • Inspection – Use your thumbnail to scratch the bark from a young limb; if you find green tissue underneath, the plant is alive though there is no guarantee that it will recover.
  • Season of flooding – Floods that occur in the dormant season will not harm trees.

Recovery of flood-damaged trees – reduce future stress 

  • Remove sediment that has accumulated on the soil surface.
  • Fertilization – Lightly fertilize with up to 1 pound of nitrogen per 1,000 square feet of soil surface.
  • Pests – Scout for insects and diseases and treat as necessary.
  • Damaged bark – Remove loose bark and carefully trace around wounds with a sharp knife to remove loose bark; do not use pruning paints or wound sealers.
  • Remove only dead branches and limbs. Do not top trees.
  • Recovery – Trees or shrubs may take up to five years to recover.
Tree Trimming Line
Photo Credit:
Dave Haasser, NDSU Photo

Tree removal

  • Flood-damaged trees may fall over in high winds because of weakened root systems and/or saturated soils.
  • Hire a professional arborist for removing large branches and trees.

Tolerance to Soil Saturation or Surface Ponding During Growing Season

Trees

Often able to withstand more than three weeks

  • Ash – green, black, Manchurian
  • Boxelder
  • Cottonwood
  • Common hackberry
  • Willows

Able to withstand one to three weeks

  • Silver maple
  • Freeman maples (‘Autumn Blaze,’ ‘Sienna Glen,’ and others)
  • River birch
  • Russian-olive
  • Honeylocust
  • Quaking aspen
  • Bur oak
  • American and hybrid elms
  • Arborvitae

Unable to withstand more than seven days

  • Norway maple
  • Sugar maple
  • Ohio buckeye
  • Paper birch
  • Hawthorns
  • Black walnut
  • Apples and crabapples
  • Mountain-ash
  • American linden (basswood)
  • Siberian elm
  • Siberian larch
  • Junipers (including Eastern redcedar)
  • Pines
  • Spruces

Shrubs

Able to withstand more than three weeks

  • Redosier dogwood
  • Willows
  • Nannyberry
  • American cranberrybush

Able to withstand one to three weeks

  • Black chokeberry
  • Silky dogwood
  • Honeysuckles
  • American black currant
  • Eastern arborvitae

Unable to withstand more than seven days

  • Juneberry
  • Cotoneasters
  • Euonymus
  • Forsythia
  • Cherries, plums, apricots, peaches (genus Prunus)
  • Golden currant
  • Lilacs
  • Yews