California lawmakers and regulators are working quickly to develop mandatory detection and prevention policies against the Asian citrus psyllid and Huanglongbing disease which threaten the state’s $1.3 billion fresh citrus industry.

WESTERN CITRUS nurserymen view protective structures as an effective method to keep disease-carrying insects off nursery stock. Pictured is a screenhouse at Sunset Nursery in Yuma, Ariz.

State Senate Bill 140, authored by Sen. Ellen Corbett, D-San Leandro, would create a mandatory Citrus Nursery Stock Pest Cleanliness Program within the California Department of Food and Agriculture (CDFA) to protect nursery stock from pests, diseases, and other threats.

“The bill’s main purpose is to protect the mother stock in citrus nurseries,” Sen. Corbett said. “It gives nursery growers the opportunity to have an inspection program to keep the citrus psyllid out of nursery stock.”

Sen. Corbett predicts the Senate-passed bill will receive state assembly approval and Gov. Arnold Schwarzenegger’s signature once the state’s budget impasse is settled.

The Asian citrus psyllid (ACP), Diaphorina citri, is the primary vector of Huanglongbing disease (HLB), or citrus greening. HLB causes smaller, misshaped, and sour-tasting citrus. Every HLB-infected tree dies within two years.

More than 1,300 psyllids have been found in California’s San Diego and Imperial counties. HLB has not been found in California. However, industry leaders admit it is only a matter of time before HLB is found in California.

ACP-HLB has brought Florida’s citrus juice industry to its knees. All 32 citrus-producing counties have HLB.

In mid-July a HLB-infected psyllid was confirmed in the municipality of Tizimín in Mexico’s state of Yucatan.

CDFA is developing regulations to carry out the citrus cleanliness program. CDFA’s proposal mandates the testing of all mother trees (budwood source) for disease in California, says CDFA spokesperson Steve Lyle.

Under the plan, CDFA would test mother trees annually for HLB; every five years for citrus stubborn, citrus psorosis, and viroids; plus continue an annual mandatory test for citrus tristeza virus (CTV), Lyle says. The frequency would decrease after the initial five-year-testing period.

CDFA would spot test in increase trees for HLB and CTV. A CTV quarantine has existed since the 1950s in many California citrus-growing areas.

Currently, any tree is eligible for registration with CDFA as a budwood source tree once it tests negative for CTV, psorosis, and viroids. If the proposed regulations take effect, propagative material must pass through extensive testing at the Citrus Clonal Protection Program prior to eligibility in the citrus cleanliness program.

The CDFA proposal also requires mother trees be placed within protective, insect-proof structures by Jan. 1, 2012, to exclude citrus disease vectors. Increase trees would face the same requirement one year later. Nursery stock is not included.

The protective structures must include double entryways that incorporate positive air pressure to the outside environment. Other requirements: an enclosed vestibule to provide for the ingress and egress of nursery stock, equipment, and supplies; and insect exclusion screening or a non-permeable covering with no gaps. Air holes in the screens must be small enough to exclude the tiny cotton aphid.

A regulatory official must approve new structures prior to planting or moving stock. Existing structures which already meet the performance standard may be grandfathered into the program.

Structure inspections would occur twice a year. Each structure would have CDFA-provided sticky insect traps. Growers would return the used traps to CDFA.

Lyle says citrus protective structures in California are recommended by scientists and industry representatives knowledgeable of ACP and HLB in California, Florida, and Brazil.

CDFA gathered input for the proposed regulations from citrus nursery and commercial fruit production representatives during three meetings held this spring and summer.

CDFA is developing the costs of the proposed regulations to be paid by the nursery industry, Lyle says. Nurserymen would also bear the financial burden of expensive protective structures.

Critical to the plant testing and structure requirements is to ensure pest- and disease-free nursery stock are sold to commercial and retail operations. ACP and HLB can attack any citrus tree whether in a neighborhood yard, commercial grove, or nursery.

In Florida, HLB-infected nursery stock was planted in citrus groves. That is one reason why the disease spread quickly through the state’s citrus-growing region. The first psyllid was found in the Sunshine State in 1998 followed by HLB in 2005.

ACP and HLB have not been found in Arizona.

California nurserymen understand the seriousness of the ACP-HLB threat and many support the protective structure concept. Finding the dollars to protect the plants is another issue. Many nurseries are already financially challenged by the recession and other factors. Protective structures and plant testing could force some nurseries out of the citrus stock business. Several large nurseries already have budwood under protective structure.

SB 140 is supported by California Citrus Mutual (CCM), a citrus-producer trade association based in Exeter, Calif.

“We’re supporting the legislation because it mandates a budwood testing program and establishes the criteria and timeline for providing adequate protection to our (commercial grower) industry from an infected nursery plant,” said Joel Nelsen, CCM president.

Nelsen stopped short of endorsing mandatory protective structures yet stressed the importance that nurserymen provide disease-free plants to commercial growers.

“We support the nursery industry in taking adequate steps. We’re not going to mandate anything on them,” Nelsen said. “If they are not adequately protected and are in an ACP-infested area, we’re not going to buy plants from them. They will be limited to moving inventory within the quarantine area.”

When asked when nurseries should have plants under protective structures, Nelson chuckled “yesterday.”

The California Citrus Nursery Society (CCNS) which represents several dozen nurseries supports SB 140. While its board has no position on the mandatory structure proposal, the organization is providing valuable information to nurserymen to assist them in important decisions.

“I think most citrus nurserymen recognize there is a high likelihood that they’ll be forced to be inside protective structures,” said Tom Delfino, CCNS executive director.

“Some nurserymen are considering growing other nursery (non-citrus) stock,” Delfino said. “Some are already forging ahead with protective structures for (citrus) budwood source trees and are considering the placement of increase trees under structure. Some nurserymen are still thinking about it.”

Don Dillon, vice president, Four Winds Nursery, Fremont, Calif., asked Sen. Corbett to introduce the ACP-HLB legislation. Dillon grows citrus stock within the senator’s district in Alameda County.

“We’ve always been concerned about disease issues and have supported certification programs to keep nursery stock clean; whether for commercial or retail use,” Dillon said at a ACP-HLB workshop in Riverside, Calif.

Dillon supports mandatory protective structures. “I think that’s the smartest thing to do.” The costs are a huge challenge, he noted.

Citrus nurseryman Sam Glick, manager, Young’s Nursery, Thermal, Calif., shared his opposition to SB 140 in a letter to Senate Food and Agriculture Committee Chair Sen. Dean Florez.

Glick believes the bill gives CDFA broad and sweeping authority to establish and enforce new regulations with little public oversight. He says the legislation also lacks monetary compensation to nurseries and other impacted businesses for costs born by nursery stock growers for a program that would benefit the entire state.

“Farming is not the most profitable business and we just want to make sure there’s some sharing of the (financial) burden between farmers and government,” Glick said.

About 400,000 trees are grown annually at Young’s Nursery, mostly for the commercial citrus industry.

California’s citrus nursery industry contributes about $25 million annually to California’s economy.

email: [email protected]