oak death from drought

Oak trees dying due to drought

Updated: June 14, 2021

Factors that contribute to the decline of trees and shrubs

  • Tree and shrub problems, to a large degree, are not due to diseases or insects. Professionally, the causes are often referred to as abiotic (Latin word meaning “without life”) causes. Simply, we can refer to them as stress factors.
  • It may take a long time for symptoms to appear or it can appear very suddenly. But, by the time it becomes obvious that a tree or shrub is dying, it is often too late to correct the problem.
  • Diagnosing abiotic plant problems can be difficult. Multiple factors may be involved, including evidence of insects or disease. 
  • Stressed plants are more susceptible to disease and insect problems. 
  • Determining the difference between the “symptom” and the “sign” of a problem is the first step in making a diagnosis.
  • Careful site selection, proper planting, protecting trunks and roots from mechanical damage, watering during plant establishment, and during dry weather are some ways to protect plants from stress factors.
  • It is important to recognize stress symptoms early to prevent further decline.
  • Trees planted in natural areas and native soil have a much longer lifespan than trees planted in a typical home or commercial landscape.

Symptoms and signs

Symptoms

curled leaves from drought stress
Symptoms of drought-stress leaves, leaf curl and leaf scorch

A “symptom” is an unnatural change in a plant’s appearance or growth caused by one or more factors. Example: wilting of leaves or early fall color.

  • Small leaf size
  • Wilted leaves
  • Early fall color
  • Early leaf drop
  • Very slow growth
  • Poor foliage color
  • Scorched or leaves that appear burnt
  • Sparse growth
  • Branch die-back
  • Large crops of fruit or nuts
  • Development of suckers or water sprouts
  • Combination of any of the above
  • Death of the plant

Signs

cottony camellia scale
Cottony camellia scale, Brian Kunkel, University of Delaware, Bugwood.org

A “sign” is the actual presence of organisms such as insects, mites, or mushrooms. Examples: Insect droppings on leaves; the white coating on crepe myrtle leaves caused by the powdery mildew fungus.

  • Active insect infestation
  • Insect feeding damage
  • Evidence of insect's presence, like the remains of eggs or pupal cases
  • Mushrooms
  • White coating on leaves caused by powdery mildew fungus

Adapted from publication HG 201 Homeowner Landscape Series: Common Cultural and Environmental Problems in Landscapes, Authors: Dave Clement, Ph.D., Principal Agent, University of Maryland Extension and Mary Kay Malinoski, Principal Agent (retired), University of Maryland Extension. And publication HG 86 Common Abiotic Plant Problems, Author: Raymond Bosmans, Professor Emeritus University of Maryland.

Edited by Jon Traunfeld, HGIC Director and University of Maryland Extension Specialist. Complied by Debra Ricigliano, HGIC.