Olaf Kenneth Ribeiro has a Ph.D. in Plant Pathology & a Diploma in Tropical Agriculture. He is also a certified Arborist. Olaf has over 30 years' experience in diagnosing plant and tree health problems both, in the U.S and overseas. His book "Sourcebook of the genus Phytophthora" (1978) 420 pp. is presently used in several dozen countries. He is also the co-author with Dr. Don Erwin (University of California), of the book Phytophthora Diseases Worldwide published by APS Press (1996). 592 pp. 2nd. Edition 2005 that is presently used worldwide. He has published over 50 scientific papers in refereed international journals and also written several popular articles on Plant Diseases and on the Dynamic Interactions between Microbes, Soil and Roots. Olaf has been an invited speaker at numerous National & International meetings and Conferences and has also presented seminars to Arborists nationally and internationally on Tree Health. His has been recognized by the Wall Street Journal and appeared on the NBC Today Show for his work with trees and is also featured as one of the Island Stewards in "In Praise of Island Stewards" by Joel Sackett. Olaf Ribeiro is the former owner of Ribeiro Plant Lab, Inc. an Agricultural/Horticultural/Arboricultural Consulting & Plant Disease Diagnostic Company based on Bainbridge Island, WA and of Ribeiro Tree Evaluations, Inc. Presently, he is the owner of Ribeiro Consultants also based on Bainbridge Island, WA.