The use of antimicrobials is one of the few effective treatments against HLB in citrus trees. However, penetration of substances into trees is hindered by the presence of protective layers such as the thick cuticle on leaves, and cork on stems. To overcome the obstacles imposed by the cuticle to increase penetration of externally supplied substances, we have successfully tested laser light. Laser light technology involves the use of low level light energy to disperse the cuticle creating microscopic and superficial indentations of approximately 250 �m. In doing so, infiltration of substances into the leaf is greatly enhanced. Once inside the leaf tissue, substances can follow the natural transport pathway through the apoplast, absorbed by phloem cells, and transported throughout the tree. Specific goals are 1. To build and test a more flexible and elaborate laser machine that will allow for more decisive experiments in the greenhouse; 2. Test for the effectiveness of several antimicrobials; 3. Carry out initial field experiments with young trees. The laser machine was delivered and tested under laboratory conditions. A series of initial experiments were conducted to fine tune the machine in terms of laser energy, distance, speed of laser and striking angle. All these parameters have been determined for optimal efficiency. Experiments aimed at quantify the enhanced penetration of applied substances into lasered leaves compared to unlasered leaves were performed with fluorescent deoxyglucose (NBDG) given that a system to measure oxytetracycline has not been refined. Our experiments showed that laser light enhanced penetration of NBDG approximately 4,500 times per 27 mm2. These experiments were performed in both healthy and HLB affected trees with similar results. Additional experiments to test for possible dessication and effect of leaf age were performed. Although dessication of lasered leaves was noticed in greenhouse trees, surprisingly no dessication (leaf curling) was noted in field grown trees eve in the absence of applied wax. Number of laser episodes per leaf was tested in young and mature leaves. Young leaves are physically incapable to sustain any laser treatment whereas mature leaves are capable of weathering only one. Assessment of oxytetracycline penetration is being halted until a quantitative method is refined. At the moment of writing this report, DOC personnel have refined their HPLC and we are ready to complete this last phase of the project.