Individual protective covers (IPCs) to prevent Asian citrus psyllid and Candidatus Liberibacter asiaticus from establishing in newly planted citrus trees

Following the discovery of Asian citrus psyllid (ACP) in 1998 and Huanglongbing (HLB) in 2005, this destructive disease associated with the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas) now affects most mature citrus trees in Florida. Despite the endemic presence of ACP and HLB, Florida citrus growers continue to plant new trees. The young trees are more vulnerable to both ACP infestation and CLas infection; therefore, protection from the vector psyllid by exclusion or other control methods is of paramount importance. Individual protective covers (IPCs), bags made from fine mesh netting, are a vector exclusion tool, which could prevent psyllids from transmitting CLas to young trees during the early years of growth. The use of IPCs is an environmentally friendly pest management strategy, contrary to the frequent use of insecticides to control ACPs. In this study, we investigated the efficacy of IPCs to protect trees from ACP and CLas infection in a citrus grove in southwest Florida during the first two years after planting. IPCs were compared against insecticide applications to control ACPs and tree health and growth were assessed. We found that IPCs effectively excluded psyllids, prevented CLas infection, altered microclimatic conditions in the tree canopy, and positively influenced most of the horticultural traits measured. However, IPCs promoted the incidence of other "diseases" such as greasy spot and sooty mold and of scale insects but reduced occurrence of citrus canker and citrus leaf miner. This suggests that use of IPCs may be an effective approach to protect young trees from ACP and HLB, but integrated pest management approaches will be needed for other pests during IPC use and after removal to maintain overall health of citrus trees.