A well-attended meeting in Tulare, Calif., was evidence the citrus industry believes the invasion of the Asian citrus psyllid (ACP) into the heart of the state’s citrus belt is a “when — not if” situation.
The pest is knocking at the door to the San Joaquin Valley, just to the west in Ventura County where several ACP were found in yellow panel traps, most recently in October. With the pest comes the threat of the fatal citrus disease Huanglongbing (HLB). The pest and the disease are responsible for sweeping losses to the Florida citrus industry and much higher production costs due to pesticide applications. HLB has not been found in California. None of the ACP trapped so far in the state were carrying the bacteria.
Henry Gonzales, Ventura County agriculture commissioner, told growers, packers, PCAs and others that he began preparing for the inevitable in 2008 when ACP was found in Imperial and San Diego counties.
“We didn’t want the same experience that occurred in 1994 with the Medfly,” said Gonzales, referring to widespread public resistance to pesticide sprays to knock down populations.
“What Ventura County experienced may not be the same in the valley,” Gonzales added. “With finds in residential settings there was a fear that eradication would not be allowed. We wanted people to understand why we need to keep this pest out or eradicate it if it’s found here.”
Gonzales said he began outreach programs to the county government and urban residents to education them about the pest and its probable effect on the county’s valuable citrus industry plus their own backyard trees. Ventura County leads the state in lemon production with more than 17,000 acres. The county also has citrus packinghouses that pack fruit from Southern California counties where ACP has been found.
Gonzales said the county trained inspectors and placed traps in packinghouses. Citrus shipments from infested counties were subject to rejection if they contained leaves and twigs – possible ACP carriers. Green waste trucked in from urban areas was also suspect.
With the first ACP find in Ventura County in December 2010, Gonzales said he had the option of placing the entire county under quarantine or a 25-mile radius around the site where ACP was trapped. A countywide quarantine area made more sense, he said, because it made it easier to move fruit.
Continued state funding for ACP suppression in urban areas is a major concern, Gonzales said. The state has been treating infested areas, but if it is determined that they are not able to keep populations down, it may not continue.
Goal is to buy time
Now that Ventura has the pest, Gonzales said the focus should be on eradication. Not all growers are on board with that, he added. Some believe that one find does not justify the expense of additional pesticide applications, especially if the grove is not within 400 meters of a find.
“That’s wrong. If we don’t stop it now, we will be treating it all the time,” Gonzales warned. Fruit from untreated groves may not be accepted at packinghouses.
When ACP arrives in the Valley, there is a treatment strategy in place according to University of California citrus pest specialist Beth Grafton-Cardwell.
The goal is to buy time, slow the spread of the pest until researchers can develop solutions to the disease.
No one treatment works perfectly, Grafton-Cardwell said. The basic strategy is to use two insecticide groups — foliar and systemic, to ensure all life stages are targeted. The recommended one-two punch is a pyrethroid and a neonicotinoid.
When only a few ACP are trapped, those two products will suppress for a long period. With multiple ACP sites the same strategy is recommended along with monitoring. If ACP is found in less than nine months after treatment, Grafton-Cardwell said that continuous treatment is warranted.
“Be aggressive up front or you will see them pop up again and again,” she warned.
Growers should also rotate products to stress the pest in different ways. Applications are more effective in late fall and early spring. The web site that lists the recommended sprays is at http://ucanr.org/sites/KACCCitrusEntomology.
Products that comply with organic standards are not effective and organic growers need to find solutions, Grafton-Cardwell added.
Biological solutions — the parasitic wasps that are currently being evaluated — are not going to be a panacea, but they will be a component in control.
Pesticide applications in citrus can be tricky at certain times of the year. There are restrictions during bloom to protect bees. Some products are approved for use in the presence of bees, Grafton-Cardwell said, and growers will have to be creative to find solutions.
Ted Batkin, one of the leads in the state’s fight to control ACP, stressed that all citrus growers have a plan in place prior to an ACP find. It is likely that the first Valley find will trigger a valley-wide rather than county-by-county quarantine, he said. Batkin, who started the ACP-HLB Task Force in 2005, said growers should understand what an ACP infestation means for them and know the state regulations for suppression. Plans should also be in place for cleaning fruit prior to moving front groves.
“Don’t wait until it happens, know where machinery is located, know who to call and specify who is going to take the lead,” Batkin advised.
Batkin, who leads the Visalia-based Citrus Research Board, said the grower-funded program is planning a citrus conference in October, which will focus on ACP controls including spray demonstrations and integrated pest control programs.