When the Asian citrus psyllid was detected in the San Diego area about four years ago, California’s citrus grower-shippers knew it was only a matter of time before the pest started infecting trees with citrus greening disease, more formally known as huanglongbing or HLB.
The disease, which already has had a serious impact on Florida’s citrus industry, attacks the vascular system of plants and can kill trees within two years. It’s not harmful to humans or animals.
The psyllid now has been detected in several California counties, and, as expected, the disease itself showed up in a backyard tree in Hacienda Heights earlier this year.
The area was quarantined, and, as of early fall, the disease had not been detected anywhere else.
Fortunately for Central Valley growers, the disease has been confined to the southern part of the state, so far.
“The (psyllid) numbers have remained low in San Diego County, in Imperial County and out into the desert,” said Bob Blakely, director of industry relations for California Citrus Mutual, Exeter.
The pests are starting to move eastward into Riverside County, but they remain in urban areas, not in the major growing districts.
The California Department of Food and Agriculture and other agencies are working to control the psyllids.
Backyard treatments have been reduced because of budgetary considerations. Instead, buffer zones have been set up in commercial areas, and natural enemies, like predatory wasps, have been introduced to help control the psyllids.
“I think our efforts are slowing them down,” Blakely said. “We believe that we’ve had an impact.”
Using natural predators also helps reduce the amount of pesticide that is sprayed in urban areas.
State officials hope that homeowners who want to keep their citrus trees will do their own treating.
“We’ve got quite an educational campaign going on to educate homeowners about how to control the psyllid in the backyards and in their citrus,” Blakely said.
Once the disease is spotted, the only solution is to remove the tree from the environment so it won’t serve as source to spread HLB to other trees.
Neighboring Arizona is not immune from the psyllid, however. Mark Spencer, secretary-treasurer and chief operating officer for Associated Citrus Packers Inc. in Yuma, Ariz., said it’s been about six months since any psyllids have been detected.
“They have not been very widespread here,” he said.