Pattern of damage produced on vegetation by smog

A new expression of injury to vegetation caused by air pollutants in the Los Angeles area has been observed in the field following smog. A type of banding, not hitherto described, occurs in the same location on leaves of the same age, the location appearing to be related to cellular maturity. A distinct pattern of banding was observed in some form on all but one of 50 species studied following a single exposure to smog. The area damaged was that in which cellular differentiation had most recently occurred. Fumigations with gasoline mixed with ozone and with car exhaust fumes mixed with ozone have produced these bands. Familiarity with this pattern makes it possible to determine by visual inspection whether damage has been caused by smog or by some other agent, and to establish the fact that smog has been present, even though no other measurements have been made. It has also assisted in establishing the fact that gasoline vapors and car exhaust gases are potential sources of crop damage. 15 references, 3 figures.