Sunscald, Frost, Chemicals, Air Pollution, Heat, Flooding, Drought

From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.

Importance- Noninfectious diseases, depending on their cause and severity, can result in premature defoliation, stem injuries, branch dieback, predisposition to pathogens and insects, and tree death.

Look For: Off-color, chlorotic, or necrotic foliage. Patches of dead bark, usually on the south side of the tree. Wilted foliage, branch dieback. Premature defoliation. Distorted leaves.

Chemical Damage (herbicide)

Noninfectious diseases produce many different symptoms. Often these symptoms may resemble those produced by insects, fungi, or other biotic agents. Careful observation and knowledge of the management history, including any chemical treatments applied, are needed to distinguish those diseases caused by abiotic factors from those caused by biotic agents.

Biology- Noninfectious diseases are those not caused by fungi, bacteria, viruses, or nematodes. Instead, they result from extremes in temperature, water supply, chemicals (both in the air and soil), nutrient imbalances, soil compaction, or various mechanical injuries. Herbicides and fertilizers that are improperly used can damage trees.
Nutrient Imbalance	Sunscald

Monitoring- Observe trees for symptoms of damage that cannot be associated with biotic agents. Carefully examine trees after severe weather or after chemical or cultural treatments. Stressed trees are often infected by fungi or attacked by insects.

Control: Prevention is usually the best control. Plant poplars on sites that will allow good tree growth and avoid stress-related diseases. Provide adequate water, nutrients, and weed control. Apply herbicides carefully to avoid damaging poplars.
Chemical Damage	Chemical Damage

For Additional Information- The causes of noninfectious diseases are often complex and difficult to diagnose. If you can't determine the cause for a particular condition, contact your county, forestry, or plant pathology extension office.

Hail Damage.	Frost damage to new shoot.

Stem breakage at sunscald. Note decay fungi fruiting on affected area.	Drought stress. Note sparse foliage.

Physiological leaf symptoms.	Frost damage to leaves.