“There is no threat at this time to commercial citrus but that’s one of the reasons we want to stop the spread as quickly as we can,” Leavitt told reporters.   

Western Farm Press asked Leavitt for the distance from the residential HLB find site to the nearest commercial citrus orchard. He said a commercial orchard was located 14 miles away in northern Orange County.

California’s commercial citrus industry is valued at nearly $2 billion. About 75 percent of U.S. fresh market citrus is grown in California.

The ACP is the primary vector of HLB but the disease can also be spread by budwood. California is the last major citrus-growing area in the world to get HLB; a disease caused by the Liberibacter bacteria.

HLB is considered the world’s worst disease of citrus. Each infected tree dies within several years. Leavitt says an HLB-infected citrus plant results in bitter-tasting fruit, discolored and odd-shaped fruit, and decreased yields until the tree dies.

California commercial citrus growers should be on high alert.

Beth Grafton-Cardwell, University of California-Davis IPM specialist and research entomologist, says this first case of HLB was found exactly where many thought it would – in an L.A. County residential area.

Grafton-Cardwell says it is essential that CDFA move quickly in the find area to prevent the possible spread into commercial citrus.

“Hopefully the CDFA will be incredibly aggressive about attacking this tree and the neighborhood and will keep an incredible vigilance to determine if other trees come up positive.”

A difficult realization is tree symptoms do not show up for awhile after infection. A tree can transmit the disease to a psyllid without showing symptoms.

“CDFA must be right on top of testing, testing, testing everything in that area,” Grafton-Cardwell said. “If we’re lucky, it is a one tree problem.”

She says the HLB find is yet another reason for commercial citrus growers and pest control advisers to keep an eye on citrus blocks for the pest and disease.

California’s first HLB case is bad timing. Citrus trees are in the spring flush-growth cycle, Grafton-Cardwell says. Psyllids are attracted to new flush which can spread the disease even faster. 

cblake@farmress.com