This falls to earth in rain and is a form of Nitrogen that is readily available for plants to use. Red spruce appears to be one such species prone to show this symptom of indirect air pollution injury. Ozone Injury - Non Point Source Injury 2. Another important air pollutant that affects tree growth is ozone . Here on this hillside in the Appalachian mountains white pine exhibits symptoms of severe ozone injury.
White pine is sensitive to the pollutant but shows considerable variation within the species.
Ozone on white pine results in tip burn, chlorosis and mottling of the needle. On hardwood species ozone injury appears as a purple discoloration or stippling of the upper surface. Here an Aspen has severe interveinal stippling along with chlorosis and necrosis. Point Source Injury 6. Interveinal necrosis is the most common symptom of sulfur dioxide injury.