The Potential Economic Benefits of Preventative and Mitigating Practices to Manage Citrus Greening Disease in California

Huanglongbing (HLB) is a disease that infects trees with the bacterium Candidatus Liberibacter asiaticus (CLas), which leads to fruit drop, yield reduction, and eventual death. HLB presents a significant threat to citrus production worldwide, jeopardizing its economic viability. There is currently no known cure for HLB. Past and current attempts at controlling the spread of HLB have primarily focused on spraying insecticides for Asian citrus psyllid (ACP) control, which vector CLas. Rogueing of infected trees has also been considered but has been largely abandoned given very limited effectiveness at curbing the spread of HLB. Recent research has examined the use of antibiotics, such as oxytetracycline (OTC), as potential solutions to mitigate HLB. OTC is a heat-tolerant member of the tetracycline class of antibiotics, which was first administrated through trunk injection as a pesticide for use in peaches in 1974. Our study evaluates the economic implications of OTC trunk injections as an HLB treatment in the event that a Navel orange grove in California was infected with HLB. We develop an empirical model to evaluate the effectiveness of OTC in reducing economic losses associated with HLB. The results show that the benefits of OTC treatment in terms of greater yields outweigh its cost but only when the high price of $23.29 USD per 37.5 lb box is observed. Furthermore, our model incorporates the use of insecticides in conjunction with OTC to evaluate the combined effects of these management and prevention strategies for HLB infections. Assuming the application of insecticides at an 80% efficiency in reducing the ACP population, profitability is first achieved in year 16 for average prices and yields, reaching $762.83 USD per acre. A scenario in which both prices and yields are high was also evaluated, in which the treatment becomes profitable in year 8 at every OTC efficiency. In the 20th year, cumulative discounted profits per acre are $107,278, $117,244, and $124,936 USD for low, average, and high OTC efficacy, respectively.