Grove-First: A new framework to find safe, available and affordable solutions to citrus greening disease

Citrus greening (Huanglongbing, HLB) is a devastating bacterial disease associated with plant infection by fastidious, insect vector-borne bacteria in the genus Liberibacter. The only known vectors are Diaphorina citri and Trioza erytreae. With over a billion dollars invested to find a solution, the only tool available to growers to combat this disease is direct injection of oxytetracycline. However, there are limitations as to how often it can be used over the course of three years, and it is only available for use in Florida. Additionally, there is the stigma of overusing antibiotics within agricultural commodities and the concern of antibiotic resistance development. To address these concerns, we created the ‘Grove-First’ framework. Bypassing lab and greenhouse-based screens, this framework allows us to efficiently screen molecules in production level citrus groves to select those that result in enhanced tree health over a season under extreme HLB and psyllid pressure. In 2023, 88 molecules were injected into the scions of 8-year-old ‘Valencia’ sweet orange (Citrus × sinensis) trees grafted on ‘US-812’ (Citrus reticulata × Poncirus trifoliata) rootstock. Visual health assessments were taken prior to injection, 90- and 180-days post-injection and post-harvest to evaluate changes in the horticultural traits of each tree. Each molecule was injected into a total of three trees that had comparable health assessments at the start of the trial. Yield, fruit weight, and juice quality were measured at harvest results were compared to oxytetracycline control injections. Results show that 19 molecules performed as well or better than the controls.