Oranges Fewer and More Yellow? Researcher Points Finger at Smog

VISALIA — Smog in the San Joaquin Valley’s citrus belt may be reducing yields of Valencia oranges by as much as 25%, according to a UC Riverside researcher.

The ozone component of smog is most damaging to orange trees, which spend more energy fighting ozone and less energy producing fruit during photosynthesis, according to David Olszyk, UC Riverside physiologist.

“What we found out is that trees are not able to set as many fruit, and you get fewer oranges per tree,” Olszyk said. “To the degree you clean the air, you increase yield. We think the yields could go up as high as 25% if you really clean the air.”

Olszyk also said that smog also makes the fruit more yellow.