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Helping Flooded Trees and Shrubs (H1592)

In North Dakota, some trees and shrubs have died and others are declining because of flood-related problems. However, you can help trees and shrubs recover. This publication gives you information to help trees and shrubs.

Joseph Zeleznik, Ph.D., Extension Forester


NDSU Photo by Megan Myrdal

 Photo by Megan Myrdal, NDSU Extension Service

Symptoms of flood damage

  • Leaves – discoloration (yellowing), wilting, scorched appearance, early fall color or leaf drop
  • 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.

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.
  • 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.

NDSU Photo by Dave Haasser

Photo by David Haasser, NDSU

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
  • Eastern 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

Revised 2016

 

 

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