Rainbow has been in the tree injection game for a long time. In fact, Rainbow Ecoscience’s sister company, Rainbow Treecare, began exclusively as a tree injection company protecting elm trees in the 1970's. Tree injection has roots as far back as the 12th century. In recent times, there have been advancements in research and technology that have moved the practice of tree injection forward. This guide provides a high level overview and some of the most important things to know when it comes to tree injection.