Comparison of tools to support healthy young citrus plantings in a region with endemic huanglongbing, CLas, and Asian citrus psyllid (Diaphorina citri)

Abstract

The Florida citrus industry has been devastated by huanglongbing (HLB), a fatal citrus disease associated with a bacterium transmitted by the Asian citrus psyllid (ACP). Current management relies primarily on insecticides to reduce vector populations. Growers are interested in options for protecting new plantings including individual protective covers (IPCs), reflective mulch ground cover, and red-dyed kaolin particle films. We tested the efficacy of these tools in reducing ACP densities on young citrus trees against a grower standard control. We also quantified the effects of these treatments on other citrus pests, including citrus leafminer, spider mites, and citrus rust mites, as well as on the incidence and severity of plant pathogens, including huanglongbing and its associated pathogen (Candidatus Liberibacter asiaticus), citrus canker, greasy spot, sooty mold, and melanose. Among these treatments, the IPCs successfully excluded ACP, with no covered trees infected with HLB after two years. Trees in this treatment also showed the lowest densities of citrus leafminer infestation and citrus canker incidence. However, trees under IPCs were susceptible to other issues including sooty mold and spider mites, suggesting that there are trade-offs with using this tool. Trees in the reflective mulch and kaolin treatments did not have reduced infestation of key citrus pests and pathogens compared to the grower standard for key citrus pests and pathogens. Although IPCs cannot solve all citrus ailments, we show that they are a promising tool for protecting young citrus trees from ACP and HLB.