What symptom indicates air pollution caused by ozone?

Fleeking and stippling are specific symptoms that are notably associated with ozone pollution in plants. This occurs when ozone, a reactive gas found in smog, infiltrates leaves through the stomata. Within the leaf tissue, ozone can cause cellular damage, leading to the development of light-colored flecks or stipples, which provide a visual indicator of the harmful effects of ozone on plant health.

The other symptoms listed do not directly indicate air pollution caused by ozone. Brown leaf margins are more often associated with factors such as drought stress or nutrient deficiencies. Leaf curling can be indicative of numerous stressors, including herbicide damage or environmental conditions like drought. Growth atrophies could signal a variety of issues, such as nutrient deficiency or pest damage, rather than specifically pointing to ozone injury. Therefore, fleeking and stippling stands out as the most recognized symptom related to ozone pollution.