Citrus canker found at UF research facility, will halt numerous experiments

July 1, 2005

FORT PIERCE, Fla. — Citrus canker, one of the most destructive diseases affecting Florida’s $9 billion citrus industry, has been found in a University of Florida citrus research grove at UF’s Indian River Research and Education Center, or IRREC, near Fort Pierce.

The discovery, confirmed Thursday by the Florida Department of Agriculture and Consumer Services, Division of Plant Industry, will likely require officials to destroy all of the citrus trees in IRREC’s groves, halting all citrus research projects there, said Brian Scully, director of the center and a professor of horticulture with UF’s Institute of Food and Agricultural Sciences, or UF/IFAS.

“This canker infection, though contained in the early stages, will temporarily halt all of our citrus research projects at the center,” Scully said. “It will take us a number of years to recover, but ultimately this setback will offer us a fresh start and improved groves in which to conduct research. However, we will continue to conduct our collaborative research in commercial groves with the cooperation of private industry.”

The disease, caused by bacteria in the genus Xanthomonas, can affect all citrus varieties, including grapefruit, oranges and tangerines, which are grown at IRREC, Scully said. Trees affected by the disease develop small brown lesions on leaves, stems and fruit. Citrus canker eventually reduces tree productivity if left unchecked.

IRREC employees discovered the outbreak Monday during a voluntary grove inspection, he said. UF/IFAS officials immediately reported the discovery to the Division of Plant Industry, which is responsible for the state’s Citrus Canker Eradication Program.

UF/IFAS will cooperate fully with DPI to address the situation, said Jimmy Cheek, UF senior vice president for agriculture and natural resources. Mapping efforts by the Citrus Canker Eradication Program will establish the extent of the infection and determine which groves will be affected.

“Our personnel will assist DPI in identifying all infected trees,” Cheek said. “After that, we’ll cope with the loss of any trees that may occur. We now understand a little better what citrus growers go through when they face a canker outbreak.”

State citrus canker eradication procedures require the destruction of all infected citrus trees that are found, as well as any citrus trees located within 1,900 feet of infected citrus trees, Scully said. These measures minimize the chances the highly contagious disease will spread to other sites.

Currently, six IRREC faculty and their collaborators from other UF/IFAS facilities are conducting more than two dozen experiments in the research groves, some using trees planted 30 to 50 years ago, he said.

Citrus research efforts at IRREC emphasize plant breeding, entomology, pathology and virology, soil and water science, plant nutrition and irrigation and post-harvest physiology, Scully said.

“It is difficult to quantify the loss in terms of time, monetary value and the potential impact that our research findings have on the statewide citrus industry,” Scully said.

In addition, citrus research programs at the U.S. Department of Agriculture Horticultural Research Laboratory adjacent to IRREC are vulnerable to the effects of the canker infection in the IRREC groves, said Harold Browning, statewide coordinator for UF citrus programs in teaching, research and extension.

Scully said he believes the disease did not reach IRREC via human activity. “Our facility has been strictly following the precautions recommended by the Division of Plant Industry and used by growers,” he said.

The bacteria that cause citrus canker can spread on air currents, in rainwater, and on people, animals, plants and farm equipment, Scully said.

Ongoing canker sanitation and decontamination efforts will be stepped up at UF’s other citrus research units, including the Citrus Research and Education Center in Lake Alfred and the Southwest Florida Research and Education Center in Immokalee, said Browning, who directs the Lake Alfred center.

“There is no reason to suspect that citrus canker would have reached other IFAS facilities by way of the Indian River Research and Education Center, thanks to the many safeguards we have in place,” Browning said. “But with canker in many areas of the state, ongoing vigilance is necessary.”

UF/IFAS citrus researchers statewide have been developing plans to react to a canker find that involved UF/IFAS research plantings, Browning said.

“Florida citrus growers rely on our expertise to deliver improved citrus varieties, to address emerging citrus challenges, and to help growers implement better management practices year after year,” he said. “This setback will not affect our commitment to work with the industry to help solve their problems.”