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Helping Flooded Trees and Shrubs (H1592, Revised 2016)

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

Availability: Web only


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

 

 

Filed under: horticulture, trees, flood, disasters
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