Threshold levels for foliar injury to Populustremuloides by sulfur dioxide and ozone
- 1 June 1976
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Forest Research
- Vol. 6 (2) , 166-169
- https://doi.org/10.1139/x76-021
Abstract
The response of five Populustremuloides Michx. clones to sulfur dioxide (SO2) and ozone (O3) was studied in controlled fumigation chambers in the greenhouse. Threshold levels for foliar injury varied from clone to clone and were in the range of 0.35 to 0.65 ppm SO2 and 0.05 to 0.20 ppm O3 for 3-h exposures. Evidence was found for more-than-additive effects of the two pollutants when they were applied in combination.The most common symptoms for both SO2 and O3 injury were large bifacial chlorotic and necrotic areas which appeared within 20 to 48 h after fumigations. Sulfur dioxide injury rapidly bleached to a light tan color, whereas the O3 injury remained dark until leaf drop. Ozone injury also frequently extented across the veins, whereas SO2 injury usually did not.Keywords
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