Researchers have been looking for ways to help Florida citrus growers fight HLB, and spreading oak mulch around the drip line of citrus trees appears promising.
Lukas Hallman, a graduate student at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Indian River Research and Education Center (IRREC) is doing research to find what is in oak trees that apparently helps citrus cope with HLB. He presented his research during the March 25 Citrus Under Protective Screen Field Day hosted by UF/IFAS at Vo-LaSalle Farms in De Leon Springs.
After Hurricane Dorian caused a large oak tree to collapse on IRREC property in 2019, Hallman and U.S. Department of Agriculture (USDA) scientist Robert Shatters prepared the tree for mulch. They spread the mulch and used it for a bed under citrus trees in their research grove.
Each month, Hallman took data from the root rhizosphere under the oak-mulched citrus tree beds. According to Hallman, months of data showed oak amendments improved the soil and that the compounds in the mulch help citrus trees withstand HLB disease.
One year into his research, Hallman said data has shown an increase in phosphorous, magnesium and potassium in the soil of the mulched trees. Additionally, preliminary findings suggest that as the mulch breaks down, soil organic matter increases and more moisture is trapped in the soil, which are both beneficial to citrus trees.
Over the next two years, Hallman and his research partners at the USDA hope to identify which compounds are beneficial, where those compounds are found in the tree, which oak species hold these compounds and how much of the right compounds will control the disease.
Hallman also said the amount of data collected from the project will be increased. Moving forward, he will be measuring soil respiration and classifying the biodiversity of the root rhizosphere.