Uncovering How HLB Acts Inside a Citrus Tree

Amit Levy with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) describes research he’s conducting into the way the causal agent of HLB interacts with a citrus tree. The causal agent is the bacterium Candidatus Liberibacter asiaticus (CLas).

Levy, whose research is funded by a U.S. Department of Agriculture grant, says CLas is found in a citrus tree’s phloem. Phloem is very small, narrow tissue deep inside the tree and hard to reach, he adds.

“The bacteria is found in a very strange, sporadic way; it’s not equally distributed” and is found in only very small amounts in the phloem, says Levy, a plant pathologist at the Citrus Research and Education Center in Lake Alfred.

Trees with HLB have blockage in the phloem. “It’s (phloem) the vein of the tree, and they (veins) are getting blocked, and energy doesn’t go where it needs to go, and the tree declines,” Levy says. He adds that it’s the tree’s defense response to the bacteria that blocks the phloem in order to block the movement of the bacteria. “If we can find a way to open those veins … and let the tree roots move the sugars and the nutrients and get stronger, that can help the tree survive,” he says.  

“We don’t understand enough of the disease process and the interaction of the bacteria and the plant,” Levy says. “Our project is to really gain more knowledge.”  

This interview with Levy is featured in the November episode of the All In For Citrus podcast, a joint project of UF/IFAS and AgNet Media. Listen to the full podcast here.