Citrus Disease Prompts Talk of Genetic Engineering

Published April 1, 2010

A new citrus disease is killing off Florida crops, sparking scientists to take a serious look at genetic engineering as a long-range solution.

Worst Disease Yet
Called citrus greening, the disease is “pretty serious, and it seems to be the worst thing that’s ever faced the citrus growers,” said Robin Schoen, director of the Board on Agriculture and Natural Resources for the National Academy of Sciences.

Citrus greening is a bacterial disease that is spread by an insect, the Asian Citrus phyllid, to nearly all varieties of citrus, Schoen said. It takes between six and 18 months for the disease symptoms to manifest, and severe infections can devastate crop growth for seven to 10 years.

A news release from the National Academies of Sciences observed, “Citrus greening and measures taken to control it reduced Florida orange juice production by several percent by 2008, and losses will likely increase.”

Pesticides Losing Effectiveness
There are pesticides that kill the phyllid, Schoen said, but they are not solutions for the long term.

“They do have a pesticide they put in the soil, and trees pick it up,” Schoen explained. “That can kill a lot of insects, but once you start using that a lot, the insects get resistant, and that’s about where we’re headed now.”

Genetic Modification Offers Hope
One option to consider is genetic modification, and barring any public relations disaster, the endeavor could provide a viable and sustainable solution, Schoen said.

“I think growers feel public perception of genetically modified citrus is a concern,” she said. “That’s why they would like it if they could have something that they could just put on the roots, … so they could tell people the [chemical] doesn’t touch the actual fruit. That’s kind of what they’re hoping for.”

Howeer, any such scientific advancement would be years in the making, Schoen estimated. Growers facing crop disasters are keeping an open mind.

“Citrus greening is this new disease, and nobody knows where it comes from or how to stop it yet. But it ends up killing the trees,” said David Enochs, packing plant manager at Jennings Citrus in Oxford, Florida.

Enochs said he would not oppose genetic solutions if the disease were directly threatening his crop.

Disease Poised to Spread
The likelihood of the disease continuing to spread throughout Florida is high, Schoen says.

“There are 600,000 citrus acres, and all of it is being affected,” she noted. “About 4 percent of trees will be needed to be removed every year [due to citrus greening], and it will probably knock down production another 2 percent each year.”

Cheryl K. Chumley ([email protected]) writes from Northern Virginia.