The overall objective of this project was to develop new girdling techniques capable of stopping or limiting the movement of CLas to the roots while allowing for normal phloem transport, thereby enabling young trees to be more tolerant to HLB in the field. Two girdling patterns were designed differing in the distance photoassimilates had to travel apoplastically (around the girdle) to re-enter the unobstructed phloem. We began experimentation with the girdling design (spiral) that presents the longest distance for apoplastic movement and the longest distance for CLas (or its signal) to travel. To test the hypothesis, spiral girdles were placed on the main stem or on a lateral stem, and trees budded with HLB material above the girdle. In both instances, and within 8 months, approximately 90% of the trees became HLB+ opposite to the girdle. The results are clear indication that CLas (or its signal) is capable of movement laterally across the phloem tube side walls. Based on the convincing results using the girdle pattern, the number of trees to be tested with the checkerboard pattern was reduced. As with the spiral pattern, HLB was transmisible through the severed phloem elements. The data collected in this project offer new insights into the nature of the HLB signal, as it seems to move through physical barriers smaller then the actual size of CLas. We conclude that genetic HLB signal is sub-cellular in nature and can be transferred between non-phloem living cells. This new finding is important in that it shows that HLB causing effector is not necessarily the entire CLas bacterium. The infected HLB trees were kept to be used in current CRDF-sponsored research projects.