Understanding the relationship between transmission of CLas and eventual development of HLB symptoms is crucial to deploying our model to evaluate the effectiveness of RNAi-based psyllid control strategies. After obtaining survey data from Southern gardens, we have developed a model for the appearance of symptoms. This model is based on the assumption that inoculum accumulates at a rate proportional to the number of infected nymphs present in the citrus trees. Trees will begin to decline after a certain threshold. This threshold will be refined using data from Southern Gardens. We have had discussions with statisticians on the design of field trials to answer questions regarding how many constructs can be used in the field trial while still differentiating between constructs.