2018 ASHS Annual Conference

The Asian citrus psyllid (ACP), Diaphorina citri, is the vector for the bacteria Candidatus Liberibacter asiaticus that causes huanglongbing (HLB). It lay eggs on young leaves of new flush in order to reproduce. To minimize ACP population build-up minimum adults should be present when new flush leaves are developing. On bearing citrus trees the synchronized spring and first summer flushes should be targeted for maximum ACP control. The Citrus Flowering Monitor is an on-line program that determines when citrus flower buds begin to grow and full bloom will occur. Using this model to determine spring bud break, an adult ACP insecticide was sprayed in spring of 2017 and 2018. By monitoring all stages of ACP from this point forward it was determined when a second spray was needed. The two sprays timed in this way provided more than 60 days of reasonable ACP control. This allowed the flush to develop past the stage when adult ACP will lay eggs on it and past the 10 % open flower stage when honey bees find citrus to be a preferred nectar source. A similar timing can be developed for the first summer flush. Two sprays for ACP should allow that flush to develop past the susceptible stage for egg laying by adult ACP also. These two flushes produce about 2/3rd of the leaf area on a mature healthy citrus tree. Unfortunately HLB affected trees have some additional flush that was monitored and also treated in 2018. This procedure has the potential to minimize the direct reinfection of the new seasons major leaf area during ACP feeding.