Researchers at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) are working on automated systems that deliver HLB therapeutics into the citrus tree’s phloem, where the materials are most effective.
The project, “Development of an automated delivery system for therapeutic materials to treat HLB-infected citrus,” is in its third year. Ozgur Batuman, project director and UF/IFAS citrus pathologist, discussed project updates during the virtual UF/IFAS 2021 Ag Tech Expo.
According to Batuman, preliminary experiments determined that needle-assisted trunk infusion (NATI) was the best potential delivery method. Since then, researchers have been developing and testing different automated methods to allow growers to treat a large number of trees quickly while effectively delivering chemicals.
The first prototype that was tested was a microneedle roller. The microneedles penetrated tree bark easily on young citrus trees in the greenhouse that were less than two years old. However, this method wasn’t as effective on older trees in the field due to their thicker bark bending the microneedles.
The second prototype tested was a drill-based machine. According to Batuman, the drill-based prototype was very effective and created much cleaner holes with the use of drills. But, it was quite laborious and time consuming, so the researchers decided to move on to their original idea — a punching system.
The punching system achieved the target depth and was able to penetrate both young and old trees. However, it wasn’t effectively delivering chemicals to different parts of the plant.
The fourth and current prototype that is being evaluated is the gripping system. In this method, the trunk is gripped from both sides as hollow needles are injected into the trunk to deliver the therapeutics. Batuman says the challenge with this prototype has been keeping the needles from bending. To solve this issue, he says engineers are looking at using different gauge needles or sturdier materials.
“Right now there are more questions than answers, but we are learning a lot and … improving this technique to make it more practical to our growers in the field,” he concludes.