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U.S. Department of Energy
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Ozone injury to the foliage of Pinus ponderosa

Journal Article · · Phytopathology; (United States)
OSTI ID:5366543

Needles of ponderosa pine treated with 0.5 ppm ozone for 9-18 days under field conditions developed a chlorotic mottle, terminal die-back, and abscission similar to the needle symptoms of chlorotic decline. The chlorophyll content of needles treated with ozone for 18 days was generally less than that of ambient air controls. The chlorophyll content of needles treated with filtered air was greater than that of control needles and the amount of needle abscission was markedly reduced. Continuous air sampling for a 16-day period indicated an average daily peak oxidant concentration of 0.09 ppm in the stands of declining ponderosa pine. Smog has been associated with plant damage in the nearby San Bernardino Valley for at least 10 years. This evidence suggests that the ozone component of photochemical smog may be the principal cause of the chlorotic decline of ponderosa pine in the San Bernardino Mountains.

Research Organization:
Univ. of California, Berkeley
OSTI ID:
5366543
Journal Information:
Phytopathology; (United States), Journal Name: Phytopathology; (United States) Vol. 53; ISSN PHYTA
Country of Publication:
United States
Language:
English