The California Department of Pesticide Regulation released data showing that pesticide use in the state increased in 2010, reversing a four-year trend. More than 173 million pounds of pesticides were reported applied statewide, an increase of nearly 15 million pounds – or 9.5 percent – from 2009.

The increase reflected a 15 percent jump in acres treated with pesticides – up 9.7 million acres to a total of 75 million acres in 2010.

As in previous years, sulfur was the most highly used pesticide in both pounds applied and acres treated. By pounds, sulfur accounted for 27 percent of all reported pesticide use. Its use grew by 4.4 million pounds, or 10 percent, and 141,826 acres, or 9 percent.

Sulfur is a natural fungicide favored by both conventional and organic farmers mostly to control powdery mildew on grapes and processing tomatoes. Other pesticides with high use in 2010 treated a variety of diseases and pests that affected rice, walnuts, oranges, almonds, grapes and strawberries.

“The winter and spring of 2009 and 2010 were relatively cool and wet, which probably resulted in greater fungicide use to control mildew and other diseases,” DPR Chief Deputy Director Chris Reardon explained. “Summer and fall temperatures were also below average, which led to late harvests, more insect damage to some crops and additional treatments.”

The greatest pesticide use occurred in the San Joaquin Valley. The top five counties in order of most pesticide pounds applied in 2010 were Fresno, Kern, Tulare, San Joaquin and Madera. All are major producers of agricultural products.

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