May 1997
In the early 1940s, Southern California farmers and Cooperative Extension personnel recognized an unusual type of damage to the leaves of plants. They called upon plant pathologists at what is now the University of California at Riverside to help identify the cause.
Farmers observed that sugar beets and many other leafy vegetables were shriveled and discolored with mottled silver or bronze-colored lower leaves that made them unappetizing and unattractive.
Growers immediately pointed to industry as the culprit for releasing toxic chemicals into the atmosphere, poisoning their crops below. Gardena truck farmers were increasingly alarmed at their shrinking sugar beet harvests. Then in July 1950, Dominiguez growers brought a suit against one local chemical manufacturer, citing it as a source of industrial air pollution.
Riverside scientists were the first to determine that this sick plant syndrome was not caused by known industrial pollutants, but by "secondary" air pollutants, namely ozone and other photochemical oxidants.
Setting up plastic tent-like enclosures in an Upland, Calif., lemon orchard, Clifton Taylor, Ph.D., and Ray Thompson, Ph.D., conducted the first scientific attempt to measure the effects of smog on commercial citrus in 1950. They used elaborate equipment for comparing the effects of "natural" and synthetic air pollutants on 24 trees spread through the orchard. Thompson, then director of the research center, spearheaded the project.
To unravel the complex problem of photochemical smog, the plant researchers drew on the expertise of atmospheric chemists, beginning a collaboration between these two branches of science that continued for over two decades.
Today, research into the effects of smog continues at UCR's Statewide Air Pollution Research Center. Sophisticated analytical methods help scientists to identify and measure trace substances in the air.
Plant science studies benefited researchers tremendously by allowing the development of improved ozone monitors, exposure chambers and portable instruments. These modern-day tools have enhanced the study of plants response to polluted air.
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Contacts:
Susan Inong, Management Services Officer or Roger Atkinson, Ph.D., Director
Statewide Air Pollution Research Center
211 Fawcett Laboratory
University of California at Riverside
909-787-4191