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.
In this case sweet gum has marginal necrosis, interveinal chlorosis. This laurel oak had interveinal and marginal necrosis Heavy Metal Toxicity - Point Source Injury 9. The burning of electrical wiring resulted in heavy metals being deposited in the surrounding forests. A view of the area near the area showing complete death to the surrounding vegetation . Fortunately, this type of point-source type of pollution is becoming more rare.