“The disease can be spreading before you even see it,” he says.
But researchers are making progress to resolve that situation, as well.
“We need to find cheap, effective, high throughput methods to test thousands and thousands of trees,” he says.
Mirkov guesses conservatively that it will be a year before he’ll know for sure how successful his field test is. But he’s optimistic because of the positive results he’s already seen in the greenhouse.
In the greenhouse, trees are inoculated with the disease, which is a more severe process than they would undergo with natural infection in the field.
“We’re pretty comfortable that we have something here,” he says.
Mirkov is working with the Environmental Protection Agency, the Food and Drug Administation and the U.S. Department of Agriculture to get approval to grow the trees commercially.
“We have to jump through a lot of hoops,” he says.
He’ll even have to ensure that the process won’t hurt the honeybees used to pollinate the trees.
Speeding the process
Randall Niedz, research geneticist at the U. S. Horticultural Research Laboratory in Fort Pierce, says he hopes to speed up the process by using mature trees rather than seedlings that scientists typically use for testing and can take many years to bear fruit.
“If we can get mature tissue transformation in place, we can generate transgenics and will be able to evaluate the fruit much sooner than with seedlings,” he says.
Niedz says most experts would like to see a “very elegant solution” that, rather than kill the bacterium outright, might interrupt the biology and deactivate it, rendering the solution completely safe.
Texas A&M’s research is funded by Clewiston- based Southern Gardens Citrus, where Mirkov’s field trials are taking place.
“It’s really working out well,” Mirkov says. “It’s good industry-university collaboration.”
It will be several years at best before the trees can be sold commercially, and replacing existing trees with disease-resistant ones won’t be cheap.
“There will be a cost to get into it, but it won’t be near what we’re all dealing with in the groves today,” says Rick Kress, president of Southern Gardens.
Growers already have seen costs go up 40 percent to cover things, such as additional spraying and tree removal, he says.
The research process itself is costly.