Extended persistence of Candidatus Liberibacter asiaticus (CLas) DNA in Huanglongbing-affected citrus tissue after bacterial death

Objective: We aimed to determine the rate of Candidatus Liberibacter asiaticus (CLas) DNA disappearance from Huanglongbing (citrus greening disease)-affected citrus trees after bacterial death from heat treatment. Results: Using the leaf disc sampling method, we followed CLas qPCR Ct values in leaves of potted 'Valencia' orange trees after a heat-treatment that eliminated viable CLas. Although titer declined, CLas remained detectable 5 months after treatment. These results warn caution in interpreting experiments that use CLas titer to assess effects therapeutic treatments on diseased plants. Residual DNA may be detectable for 6 months, but the time to decay depends on pretreatment titer.