Growers' risk perception and trust in control options for huanglongbing citrus-disease in Florida and California

Citrus huanglongbing disease (HLB) is an acute bacterial disease that threatens the sustainability of citrus production across the world. In the USA, the Asian citrus psyllid (ACP) is the vector responsible for spreading the disease. Successful suppression of HLB requires action against ACP at large spatial scales, i.e. growers must cooperate. In Florida and California, the citrus production regions have been split into vector-management areas and growers are encouraged to coordinate spraying of insecticide across these (to achieve area-wide control). We surveyed growers from Florida and California, obtaining samples of opportunity at grower meetings, to assess the consensus of opinions concerning issues that influence HLB management. Our results show that a grower's perception of the risk of disease infection and their trust in control options are central to the decision on whether to join an area-wide control program. Growers' perceptions on risk and control efficacy were found to be influenced by information networks and observations about the state of the HLB epidemic and psyllid populations. Within the growers' information networks, researchers and extension agents were reported to have the largest influence on perceptions. Differences in opinion between California and Florida growers as to the efficacy of treatments could be explained as a function of experience: growers from areas with lower densities of ACP were associated with rating insecticide control more positively than those where psyllids population density was higher. Thirty percent of growers identified the expected lack of participation by other growers as a reason why they themselves would not participate in area-wide control.