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.

Pesticides with the greatest increase in pounds applied included 1,3-dichloropropene (1,3-D), a fumigant whose use went up by 2.4 million pounds, or 37 percent. It is used on strawberries, almonds, sweet potatoes, carrots, and table and raisin grapes. This fumigant is an alternative to methyl bromide, which is being phased out under an international treaty to protect the ozone layer.

Other pesticides that showed growth in pounds applied were metam-sodium, a fumigant used on carrots, processing tomatoes and potatoes; glyphosate, an herbicide used on orchard floors, rights of way and preplanting for row crops; metam-potassium, a fumigant used to prepare fields for processing tomatoes, sweet potatoes and carrots prior to planting; and kaolin, a clay-based fungicide and insecticide commonly used on organic crops.

Major crops that showed an overall increase in pounds of pesticides applied over the previous year included wine grapes, carrots, cotton, almonds, and table and raisin grapes. The data indicated declines in pounds applied to rice, processing tomatoes, alfalfa, peaches, nectarines and applications to fields before crops are planted to control pests.

DPR has the most extensive pesticide use reporting system in the United States and oversees one of the most comprehensive pesticide regulatory

programs in the world. These data support a variety of regulatory efforts, including compliance efforts for clean air and water laws, continuous evaluation to determine potential risks to human health and the environment, estimating dietary risks, protecting workers in the field, preserving endangered species, assisting product registration and review and helping local pesticide law enforcement.

Reported pesticide applications are only a portion of the pesticides sold each year. Approximately two-thirds of the pesticides sold, including chlorine used primarily for municipal water treatment and home-use pesticide products, typically are not subject to reporting.

Total pounds of pesticide active ingredients reported in each county and rank during 2009 and 2010 are posted at

One of five departments and boards within the California Environmental Protection Agency, DPR regulates the sale and use of pesticides to protect people and the environment.