California Air Resources Board

Prompted by estimates that California growers are losing as much as 25 percent of some crops to smog damage, the Air Resources Board has speeded up its research into the problem with $1 million in studies over the next five years. The studies are intended to improve loss estimates among the state's largest cash crops and could lead to development of smog-resistant varieties or cultivating practices, such as fertilizing and irrigation habits, that better protect crops. 

"Smog has cost growers in major agricultural areas hundreds of millions of dollars a year," noted Jan Sharpless, ARB Chairwoman. "Air pollution can cut the yield of some crops and cause others to lose their market value because of root or leaf damage."

"Our estimates of this loss vary, largely due to lack of information," she said. "Measuring the extent of smog damage is aggravated by the diversity of California agriculture. The state grows over 200 different crops, each of which may be affected by smog in a different way and none of which are more than 2 percent of our total production."

"We hope this research will help us better pinpoint how much growers are losing to smog carnage and give growers enough information to cut those losses and help the economic status of the state's largest industry." 

The first of the state's studies, at University of California facilities in Riverside and Parlier (Fresno County), worth $560,000, will concentrate on losses to the $1 billion a year grape industry, the state's largest crop, and the $200 million a year citrus crop, which has been forced out of some parts of California in part because of its sensitivity to smog. 

At both facilities, crops will be fumigated with combinations of oxidant, the state's biggest air quality problem, commonly known as "smog", and sulfur dioxide. Researchers hope to learn how exposure to air pollution affects the crop's normal aging and ripening processes. It is suspected that air pollution accelerates normal aging, causing crops to mature earlier but produce lower yield. Earlier studies have documented smog-caused leaf loss and root damage, and changes in texture, color and protein content of fruit, suspected to be signs of premature aging. 

U,C. Riverside also will conduct a $59,911 study on how the combination of soil salinity and air pollution affect crops. Researchers suspect that low salt levels actually increase a plant's resistance to smog damage, even though higher levels damage crops. The difference between helpful and damaging salt levels has not been documented, however. 

Upcoming experiments plan to study premature aging in a broader variety of crops and to identify stages in a crop's lite cycle when it is particularly vulnerable to smog damage or resistant to it. From these studies, researchers hope to identify cultivating practices that can be used by growers to protect crops from smog damage during sensitive growth stages. 

Results of these laboratory studies will enable researchers to better measure actual crop losses in specific regions of the state. Field studies to measure actual crop damage, which in the past have been limited to the San Joaquin Valley and Riverside, will be extended to other agriculturally rich areas, such as the Imperial, Salinas, Sacramento, Napa ana Santa Clara Valleys.