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Changing canker science

The Packer – June 29, 2009

Just how much has the science of citrus canker changed in two years? The answer to that question – as judged by federal authorities – will determine whether Florida fresh citrus can be sold in other U.S. citrus states in 2009-10.

Certainly there are high hopes, as Doug Ohlemeier of the Packer has reported in a previous blog post:

Paul Hornby, USDA APHIS Florida state plant health director, Gainesville, said he hoped the rule after a 60-day comment period would clear procedural hurdles and
become effective by early December.

Also, from The Naples News:
http://www.naplesnews.com/news/2009/jun/25/florida-may-once-again-be-able-ship-citrus-canker/

Dan Richey, CEO of Riverfront Groves LLC, a fresh fruit grower in Vero Beach, talked about the long fight to get the rules relaxed. He said it’s been like trying to get to the top of a “greasy bowl.” “We’ve haven’t fallen down,” he said. “We’re getting there.” It took a lot of support from growers, politicians and regulators to get to this point, Richey said.“If we succeed this journey will be a distant memory for this industry,” Richey said. “If we fail there will be no industry to remember the journey.” He doesn’t see failure as an option. “We are going to win this game,” he said.

TK: The Florida citrus industry’s struggle with canker has been long and full of near victories and unfortunate reversals. In June 1994, The Packer reported:

The Asian strain of citrus canker — one of the world’s most serious bacterial citrus diseases — has been completely eliminated from Florida after a nearly eight year struggle.

TK: Fast forward 13 years. In October 2007, the USDA published a “Regulatory Impact Analysis” of what was then a revised rule that acknowledged a new reality. That document described the progression of the canker issue in USDA rulemaking:

From the summary of that report:

On August 1, 2006, the United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS or the Agency) published an interim rule in the Federal Register amending the domestic quarantine regulations addressing citrus canker (7 CFR 301.75).1 The interim rule listed the entire State of Florida as a quarantined area for citrus canker and amended the requirements for the movement of regulated articles from Florida. The amended regulations were intended to control the spread of citrus canker to other commercial citrus-producing States after the U.S. Secretary of Agriculture determined that citrus canker eradication in Florida was no longer feasible in the aftermath of the tumultuous 2004 and 2005 hurricane seasons. The amended regulations (7 CFR 301.75-7) require every tree in a given grove from which fruit is intended to be moved interstate to be inspected not more than 30 days before harvest and found free of canker, require regulated fruit moved from Florida to be accompanied by a limited permit, and prohibit regulated fruit from being distributed to commercial citrus-producing States, which, under 7 CFR 301.75-5, include Arizona, California, Hawaii, Louisiana, Texas, American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands.2
Since implementation of the interim rule published in the Federal Register on August 1, 2006, APHIS has produced a risk management analysis (RMA) that concluded that “the introduction of [citrus canker] through the movement of commercially packed fresh citrus fruit is unlikely because:
• fresh citrus fruit is produced and harvested using techniques that reduce the prevalence of Xac-infected fruit;

• citrus fruit is commercially packed using techniques that reduce the prevalence of infected or contaminated fruit including disinfectant treatment for epiphytic contamination;

• mortality of Xac associated with fresh citrus fruit and/or packing materials occurs following harvest and packing;

• for a successful Xac infection that results in disease outbreaks an unlikely sequence of epidemiological events would have to occur;

• reports of citrus canker disease outbreaks linked to fresh fruit are absent; and

• large quantities of fresh citrus fruit shipped from regions with Xac have not resulted in any known outbreaks of citrus canker disease.

The RMA extends the application of an earlier APHIS pest risk analysis (PRA) entitled “Evaluation of asymptomatic citrus fruit (Citrus spp.) as a pathway for the introduction of citrus canker disease (USDA 2006) to all commercially packed and treated citrus fruit. The PRA concluded that asymptomatic, commercially produced citrus fruit that has been treated with disinfectant dips and subjected to other mitigations is not epidemiologically significant as a pathway for the introduction of citrus canker disease.

The purpose of the final rule is to amend the current regulations contained in 7 CFR 301.75 et seq. to modify the conditions under which fruit may be moved interstate from a quarantined area. The final rule is based on the conclusions of the RMA. The final rule will eliminate the requirement that the groves in which citrus fruit is produced be inspected and found free of citrus canker. Instead, the rule will require that citrus fruit produced in quarantined areas be treated with a surface disinfectant treatment in a packinghouse operating under a compliance agreement and that each lot of finished fruit will be inspected at the packinghouse and found free of visible symptoms of citrus canker. The current prohibition on the movement of fruit from a quarantined area into commercial citrus-producing States is still maintained in the regulations.

TK: So the USDA elected in 2007 to exclude Florida citrus fruit from other citrus states. Also, from that document was the enunciation of five different options considered then. This was the first option – rejected then but now apparently embraced. From the document:

Option 1

Under the first option, the Agency considered allowing the unrestricted distribution of all types and varieties of commercially packed citrus fruit to all U.S. States, including commercial citrus-producing States. This option relies on evidence that commercially packed fresh citrus fruit is unlikely to be an epidemiologically significant pathway for spreading citrus canker. Accordingly, Option 1 would have removed all APHIS restrictions on the movement of commercially produced and packed fresh citrus fruit (without stems or leaves) from regions quarantined for citrus canker to all U.S. States.

As the available evidence is not sufficient to conclude that citrus fruit cannot serve as a pathway for the introduction of citrus canker into other commercial citrus-producing areas,

Option 1 cannot be considered the preferred alternative at this time. The costs of successfully eradicating citrus canker in other commercial citrus-producing States, were it introduced, cannot be readily projected, but given the lack of success in eradicating the disease in Florida, it is reasonable to assume that eradication costs in other commercial citrus-producing States could well exceed benefits of unrestricted distribution.

TK: What is the available evidence now, a mere two years later? With the new proposed rule expected this week, it won’t be long before growers in Florida and California know how the science has changed and if it is good enough to clear the way for Florida citrus in canker infested areas to be sold in other U.S. citrus states.

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