There are many materials that will kill the bacteria (Candidatus Liberibacter asiaticus) that causes HLB. The challenge has been getting these materials to the place where the bacteria lives in citrus trees — the phloem. Some believe trunk injection might do the trick, but it is an expensive and labor-intensive practice that has limited any breakthroughs so far.
During the January 2022 All In For Citrus podcast, Ute Albrecht, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) assistant professor for plant physiology, discussed two trunk-injection projects she and other colleagues have received funding to research.
“Trunk injection to deliver product directly into the vascular system of the tree might be much more effective,” she explained. “It is used in forestry and ornamental plants to treat vascular diseases. These injections are made into the xylem of the tree. The phloem (where HLB lives) is a very thin strip in the inner bark of the tree trunk. We can’t directly inject anything into the phloem because it is too small to accept large molecules in large volumes. So, we must inject into the xylem to take advantage of its long, tubular cells that water and nutrients move through. If we inject materials into the xylem, they move on their own systemically throughout the tree. We are hoping on the way through the tree, these materials (that could potentially kill HLB) can move from the xylem into the phloem.”
Albrecht reported some surprisingly good results with some of the trunk-injection methods tested. The goal is to find or develop a more automated system of injection to reduce costs and labor requirements.
Another project she is participating in is field testing of novel materials that could be applied to kill the HLB bacteria in trees. Antibiotics used in human health have been proven effective against HLB, but the use of those agents is not desirable due to potential resistance development, which could impair human health uses. Many new molecules are being screened. Winners will be sent to Albrecht for testing in the field.
Hear more from Albrecht in the January episode of the All In For Citrus podcast, a joint project of UF/IFAS and AgNet Media.
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