Evolution of concepts in forest pathology

Foundation concepts in forest pathology are based on experiences evolving over time. Three examples will be addressed. (i) The primary concept behind education and research in forest pathology is the widely accepted attitude that disease-causing agents limit full utilization of forest resources. Therefore, we study diseases to find a weak link and then utilize this information to enhance our portion of the shared resource. The sustainable environmental issues of today have changed this concept, in my mind, to one of addressing what is the appropriate healthy amount of disease in a sustainable forest ecosystem. (ii) The initial concept that weakened understory trees and poorly managed forests deteriorate and decline over time because of numerous insults from biotic and abiotic agents has evolved into a decline disease stabilizing selection concept whereby healthy dominant trees in the forest (the survivors) are selectively killed by a combination of specifically ordered factors. (iii) The concept that heart-rot decay is initiated by infection through wounds that expose heartwood has evolved into the concept of infection in the sapwood that is compartmentalized over time in the center of the tree.