Location: Subtropical Insects and Horticulture Research
Project Number: 6034-21000-020-016-A
Project Type: Cooperative Agreement
Start Date: Jul 1, 2025
End Date: Jul 31, 2026
Objective:
Citrus Huanglongbing (HLB) disease presents a significant challenge in plant disease management. This disease is caused by the bacterium Candidatus Liberibacter asiaticus (CLas) and is transmitted by the Asian citrus psyllid (ACP). Developing molecules that are effective against CLas is a challenging task due to difficulties in manufacturing, EPA registration, and achieving successful delivery into the phloem in the field. Additionally, genetic engineering techniques, which involve the insertion of DNA into plant genomes, have seen limited adoption due to regulatory timelines and the need for growers to replace current groves to make use of this technology. Symbiont technology enables the direct delivery of complex, biologically active molecules into the host plant, streamlining the production and delivery of therapies into citrus trees for control of citrus greening disease. In this project, we will evaluate the performance of Symbiont technology in citrus groves in Florida. We will be continuing the analysis of Grove-First therapies by direct injection. Data will be collected to support the performance of Symbiont technology and injectable therapy regulatory information to obtain product registration and maintain APHIS permits at the field sites.
Approach:
In this research, we will evaluate Symbiont technology as a treatment for citrus greening disease. Trees will be measured using disease index, qPCR, fruit yield and quality, and drone imaging. Data for APHIS permits will be collected, such as detecting agrobacterium using qCPR in test trees, collecting evidence of movement of agrobacterium within inoculated trees, and evidence of movement of agrobacterium into the environment, including other trees and soil samples. Reports will be compiled in accordance with the APHIS permit conditions. We will evaluate therapies by direct injections across different citrus growing regions in Florida. Fruit will be harvested from the test sites and evaluated for treatment impacts on fruit quality. Treatments that show an improvement in fruit yield and quality metrics will be further evaluated and advanced towards product registrations.