Because the Asian citrus psyllid stakes its reproduction on new citrus flush, there is a lot of interest in tailoring management to citrus phenology. “Phenology” is an uncommon word, but it boils down to how plant development changes over time. For instance the development of the spring flowering flush is a phenological process and names like “feather flush,” “popcorn,” and “full bloom” describe phenological stages.
Gene Albrigo has been involved in phenological modeling to predict flowering intensity and bloom time since well before the HLB era. He has recently turned to using this model to help improve psyllid management in two ways: reducing psyllid reproduction on new flush through pre-emptive psyllid management, and reducing negative impacts of insecticides on bee pollinations. In other words his goal is to kill adult psyllids before they can lay eggs on tender new flush but not hurt pollinator bees with applications late in the flush, when flowers have emerged. This can be done by using the models he and collaborators developed and have maintained for more than 10 years.
Gene has worked with several regional growers, selecting some blocks to manage psyllids based on phenological predictions, leaving others as controls with calendar or sampling-based sprays.
Gene recently reported results from the first two years of developing this approach. Results are positive, with reductions in adult psyllid numbers and egg-laying using the phenology-based approach, spraying once just prior to budbreak and again about 4 weeks later. This also allowed a bloom period that was free of insecticide applications, leaving the pollinators to range at the appropriate time. These results are promising for psyllid management during the floral flush, and I expect this approach to expand to become a standard practice.