Developed by Dr. Alicyn Smart, Assistant Extension Professor & Extension Plant Pathologist, University of Maine Cooperative Extension, and Nick Goltz, Graduate Student, University of Florida. For information about UMaine Extension programs and resources, visit extension.umaine.edu. Find more of our publications and books at extension.umaine.edu/publications/. Edema (Oedema) Abiotic Disorder: Swollen growths or corky lesions on leaves