Genetic engineering option to save citrus industry
Date: 3.2.2006
Back in the early 1900s when citrus canker struck in Miami-Dade County, pumper trucks sprayed groves with kerosene, and the trees and bacteria went up in flames.
It was crude but effective, the canker was wiped out.
This time around, canker slipped out of the noose, with the help of four hurricanes in two years that crisscrossed the heartland of the state's citrus groves, spreading the airborne disease far and wide.
New science may be one of the citrus industry's saviors, after state officials conceded defeat Wednesday in the massive, costly effort to cut down infected and exposed trees over the past 10 years.
Agriculture scientists expect that the shift to living with, and managing, canker will spur research that didn't look as promising when eradication was the goal.
There is the prospect of genetically altered trees that could be made more resistant to canker, even immune. Some varieties of fruit already are naturally resistant.
Scientists also could pursue new pesticides more lethal to canker, which is harmless to humans but blemishes fruit.
Officials within the U.S. Department of Agriculture sent a letter to state officials Tuesday saying it was no longer feasible to cut down healthy trees as a way to stop canker's spread. State and federal agriculture officials plan to come up with new canker control protocols in the next few months.
The shift in policy likely will spark the state to invest considerably more resources toward developing more canker-resistant strains of citrus, said state Rep. Ralph Poppell, R-Vero Beach, co-chairman of the House Agriculture Committee.
``We should be spending considerably more now on research,'' he said.
Then there are some old-fashioned control methods used in other citrus-producing nations, such as Brazil, Argentina and Australia, where eradication programs also failed. They include strict decontamination procedures for workers and equipment, natural wind barriers and copper-based sprays that knock down the canker.
``Those are suppression activities. Those are not eradication," said Craig Meyers, Florida's deputy commissioner of agriculture, who oversees the canker program.
He said University of Florida scientists have been studying control methods in Brazil.
"Research has been ongoing on bacterial sprays," he said. "It may not just be copper, but other things ... All this stuff is going to change the face of the industry. It's going to add costs."
State lawmakers and officials want to do everything they can to protect the $9 billion industry. "Obviously, we can't imagine Florida without a vibrant and excellent citrus industry," said state Sen. Rod Smith, D-Gainesville, the Florida Senate Agriculture Committee chairman who is running for governor.
Florida's growers can live with canker, said UF professor Dean Gabriel, who studies canker issues at the Plant Pathology Department in Gainesville.
"You have to remember -- Brazil has lived with it for a very long time, and in that time they went from a minor citrus producer with canker to the No.1 producer, " he said. "You are able to live with canker, that is not a big deal."
Gabriel has an interest in developing genetically modified citrus trees, but he has delayed pursuing it while state officials were pushing their cutting program.
Now, he plans to open up those research avenues.
"We are now going to be working diligently to create these types of genetically modified trees," he said.
He doesn't yet know if it is technologically possible, and he said consumers would have to be willing to accept bio-engineered fruit.
He noted there's a precedent -- Hawaii's papaya crop was close to being destroyed by a virus before scientists tinkered with its molecular structure.
As agricultural officials search for new control methods, the one controversial tactic abandoned this week was the cutting of healthy trees within a 1,900-foot radius of an infected tree. Infected trees still will be cut down, in back yards and in groves.
Still, grove owners probably will follow the lead of their Brazilian counterparts -- self-police by cutting down areas where trees may have been exposed, Gabriel said.
"There will be self-eradication still going on," he said.
Jim Graham, a citrus-canker expert and professor of soil microbiology at the University of Florida's Citrus Research and Education Center in Lake Alfred, said homeowners who want to protect their trees aren't likely to use decontamination procedures or do four sprayings a year of a copper pesticide.
But he said one thing homeowners could do is to landscape around the property to provide a windbreak, Graham said.
For commercial operations with infected groves, the problems caused by canker vary year to year, Graham said. With the help of scientists, he said, growers will have to develop new strategies to lessen canker's damage.
"I think it's just going to be a change in the way we grow citrus," Graham said.
"Source":[ http://www.checkbiotech.org/root/index.cfm?fuseaction=news&doc_id=12021&start=1&control=142&page_start=1&page_nr=101&pg=1]
