On November 17th, 2023, we were honored to host a guest lecture by Prof. Toru Iwanami, lecturer from Tokyo University of Agriculture. In this class, we discuss about Serious Threats from Phloem-Limited Bacteria to Tree Crops, for example Citrus Greening caused by Candidatus Liberibacter asiaticus and Candidatus Liberibacter africanus, starting from symptoms, distribution, and transmission. It was a great and insightful discussion regarding phloem-limited bacteria which can be expand our understanding to studying the pathogen causing plant diseases and opening a new gates to collaboration to find the best way for new solution.