Air pollution
Air pollution damage to plants in California is caused mostly by ozone (O3). Because of the nature of air emissions and pollution control measures, sulfur dioxide (SO2) and peroxyacetyl nitrate (PAN) rarely damage plants.
Ozone and PAN are formed in the lower atmosphere through complex reactions among volatile organic compounds (VOCs), nitrogen oxides, and sunlight. Vehicle emissions and fuel burning are major sources of VOCs. Numerous petroleum-derived products (e.g., many pesticides), plants, and wildland fires also emit VOCs.
Air pollution damage is difficult to diagnose, in part because symptoms mostly develop after long-term (chronic) exposure to relatively low levels of pollution. Many of the symptoms are similar to and aggravated by those resulting from other stresses, including aeration deficit, foliar pathogens, herbicide phytotoxicity or other chemical phytotoxicity, mite or thrips feeding, and nutrient disorders.
Damage
Air pollution reduces crop yields, and in landscapes mostly stunts plant growth and discolors foliage. Damage varies with the age, cultivar, and species of plant, and with location and weather. See ozone for more on the plant-damage symptoms of this air pollutant.
Solutions
Provide proper cultural care and improve the growing environment to reduce plant stress. Where air quality is especially poor, plant the more-tolerant species listed in Abiotic Disorders of Landscape Plants. For large-scale plantings in regions where pollution exceeds air-quality standards, consider planting trees that are low emitters of VOCs.
Air pollution is best controlled at its source. Minimize VOC emissions by following IPM practices:
- Use pesticides only when necessary.
- Reduce the amount of pesticide applied.
- Spot-treat, reducing the area treated.
- Make fewer applications.
- Avoid emulsifiable concentrate (EC) formulations.
Consult the pesticide VOCs emissions calculator when choosing a product to apply.
Pollution-reduction methods include using alternative energy sources and means of transportation, properly maintaining vehicles and engines, and conserving resources and materials. Grow more plants because certain gaseous and particulate air pollutants are absorbed by bark and foliage.
For more information on ozone, see also the U.S. Department of Agriculture's Effects of Ozone Air Pollution on Plants and UC's Urban Trees and Ozone Formation.
|
Hazy air due to pollution
Yellowish patches on leaves caused by ozone
Tip burn and banding on pine needles
|
