The threat to California crops by the light brown apple moth might not be as potentially disastrous as first thought.

California may have hope in fighting light brown apple moth

Combining applications of reduced-risk insecticides with an integrated pest management (IPM) program reduced to near negligible levels crop losses caused by moth infestations in some New Zealand apple orchards, according to an article in California Agriculture, a University of California publication.

The pest, a native of Australia, was discovered for the first time in North America in early 2007 when an adult moth was found in the San Francisco Bay area. Since then, more than 100,000 moths have been trapped in a program conducted by the U.S. Department of Agriculture and the California Department of Food and Agriculture.

The resulting quarantine boundaries blanket more than 3,500 square miles of California. The USDA has projected that crop losses from widespread moth infestations in California could be in the billions of dollars annually.

The article in the January-March 2010 edition of the journal was reviewed by one of the university’s integrated pest management advisors, Lucia Varela, and scientists with the New Zealand Institute for Plant & Food Research, according to a news release. It found apple moth losses in a New Zealand apple growing region exceeded 40% in 1986. Ten years later, growers implemented the spraying and pest management program. Since 1998, crop damage has been limited to non-measurable levels up to 4%, according to the article.

“With a strategic commitment to biological control within an IPM context, California may ultimately achieve the same levels of light brown apple moth control as obtained in New Zealand,” Varela and her colleagues wrote in California Agriculture.

New Zealand’s climate is similar to that of coastal California with maximum temperatures rarely above 86 degrees and more than 25 inches of annual rain, according to the article, which could mean the combined spraying/IPM approach would work well in the state’s coastal berry and vegetable growing regions.

It does not address whether the approach would be successful in the hotter, more arid San Joaquin Valley.