Michael Rogers, University of Florida associate professor at the Citrus Research and Education Center, Lake Alfred, talks about Florida's programs to kill Asian citrus psyllids, which can carry citrus greening disease.
Michael Rogers, University of Florida associate professor at the Citrus Research and Education Center, Lake Alfred, talks about Florida's programs to kill Asian citrus psyllids, which can carry citrus greening disease.

PORTERVILLE, Calif. — Four years after an Asian citrus psyllid infestation was discovered near San Diego, the California citrus industry continues to keep the disease-carrying pest at bay.

Efforts against the psyllids in Florida and Texas, are also gaining momentum, according to presentations at the 2012 California Citrus Conference Oct. 10, which was sponsored by the Visalia-based Citrus Research Board.

“We are so far ahead of other places in the world that have this (psyllid) problem,” said Nick Hill, chairman of the California Citrus Pest and Disease Prevention Committee and managing partner of Green Leaf Farms Inc., Kingsburg. “The idea is to save our citrus industry, to save back yard citrus trees and to have this industry around for your children and their children.”

Psyllids can carry huanglongbing, the bacterial disease that destroyed more than 200,000 acres of citrus groves in Florida. The disease, also known as HLB, was detected in Texas for the first time in December.

Texas lessons

“California can learn from Texas what not to do,” said Mamoudou Setamou, associate professor for Texas A&M University, based at the Kingsville Citrus Center, Weslaco.

Psyllids were discovered in Texas in 2001, but the state’s citrus industry did not proactively fight the pest until 2006, Setamou said. Much has changed in Texas in recent years, and the psyllid population is slowly diminishing in commercial groves. The Texas Department of Agriculture established a nursery committee to ensure nursery stock is psyllid-free.

“Most, if not all nurseries, are still open-field operations,” Setamou said.

By Sept. 30, 2013, all nurseries with citrus stock will have to be enclosed.

Florida’s programs

In Florida. Nearly 40 Citrus Health Management Areas covering 480,000 (more than 85% of the total) citrus acres have been created, said Michael Rogers, University of Florida associate professor stationed at the Citrus Research and Education Center, Lake Alfred.

The free program is grower-driven and voluntary, he said. Growers coordinate psyllid control efforts, including pesticide use, to help manage infestations. A companion program, a joint effort of the state and federal departments of agriculture, uses scouts to check more than 100,000 acres of citrus every three weeks, Rogers said. The year-old programs are chalking up impressive records, and results are posted at www.flchma.org.

“We’ve seen about a 68% reduction in the finding of psyllids per block,” Rogers said, “and there are blocks where the psyllid population has been knocked back so much we can’t find any individual psyllids at all.”

California's proactive stance

California, which began to map an anti-psyllid/HLB game plan two years before the pest was discovered in the state, continues to be aggressive. In September, the Citrus Pest and Disease Prevention Committee approved a fiscal 2013 budget of $15 million, mostly generated by growers, Hill said.

Growers also agreed to increase the per-box assessment from seven cents to nine cents, he said.

A buffer zone around the Los Angeles Basin, aimed at keeping psyllids from the desert, coastal and San Joaquin Valley growing regions remains a priority, Hill said.

California is raising millions of psyllid-killing wasps at Cal Poly-Pomona, with a plan for a mass release in the next 18 months, Hill said, and an urban outreach program has been expanded in multiple languages.

A combination of a broad spectrum pesticide and a systemic pesticide on infestations has proven effective, said Beth Grafton-Cardwell, University of California at Riverside Integrated Pest Management specialist, research entomologist and director of the Lindcove Research and Extension Center, Exeter.

“Treatments can be very, very effective in terms of knocking the psyllids down so low that you don’t find them for many months, even years,” Grafton-Cardwell said. “When groups of people, whether they be urban or commercial, agree on an area-wide program and act to suppress the psyllid, they can make a huge dent in the population.”

Organic fruit, however, still remains vulnerable, Grafton-Cardwell said. Treatments need to be applied every 10-14 days, because they don’t kill all the psyllids.

“So we really don’t have an organic solution to the Asian citrus psyllid problem.”

Researchers, however, are constantly testing new products on organic citrus.

While the pest and disease have devastated much of the Florida citrus industry, the scouting program has turned into a research tool, Rogers said.

“We’re actually able to look at real world situations, not small research plots, but commercial groves on a large scale,” Rogers said.

The psyllid monitoring and the CHMA program are giving the Florida industry the opportunity to validate some things that are coming out of the university’s research program, Rogers said.