Rex joined The Care of Trees in 1989 after receiving his Ph.D. from Iowa State University, majoring in Entomology. He is a Regional Technical Advisor with the Davey Tree Expert Co./The Care of Trees, with emphasis on education and training, public relations, and diagnostics. He is an International Society of Arboriculture Board Certified Master Arborist and currently serves on the ISA Board Certified Master Arborist Test Committee.