Forest Pests: Insects, Diseases & Other Damage Agents

Air Pollution and Chemical Injuries

Solomon, J.D.; Leininger, T.D.; Wilson, A.D.; Anderson, R.L.; Thompson, L.C.; McCracken, F.I. 1993. Ash pests: A guide to major insects, diseases, air pollution injury and chemical injury. Gen. Tech. Rep. SO-96. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 45 p.

Air Pollution Injury

Ashes vary in sensitivity to air pollutants, but in general, are intermediate in sensitivity to sulfur dioxide and hydrogen fluoride emitted during various types of manufacturing processes. Sulfur dioxide kills the leaf tissue between veins, whereas hydrogen fluoride kills the leaf margin. White ash is sensitive to ozone, which causes purple stippling on upper surfaces of older foliage. Extremely sensitive cultivars may experience growth loss. The main precursors of ozone originate from automobile exhaust.

Chemical Injury

Ash trees are sensitive to many chemicals, but the most frequent damage is caused by herbicides. Symptoms are highly variable and include leaf curl, chlorosis, partial leaf necrosis, and premature leaf fall. Affected branches or the entire crown may drop its leaves and refoliate repeatedly during a single growing season. Young trees may be killed by acute exposures. Symptoms of air pollution or chemical injury may be difficult to distinguish from symptoms induced by other abiotic agents or infections caused by biotic agents.

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