Relationship of Stem Tissue Age to Frequency of Nectria Canker. W. Merrill, Professor, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. R. J. Finley, Former Undergraduate Student, School of Forest Resources, The Pennsylvania State University, University Park 16802. Plant Dis. 65:66-67. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-66.

The relationship between cumulative frequency of cankers caused by Nectria galligena and the age of the tissue when the canker became established on the main stem was sigmoidal in Betula lenta, B. papyrifera, Juglans nigra, and Sassafrass albidum. The point of change in the curve from exponential to logistic was at 3 yr for J. nigra, 5 yr for B. papyrifera, and 7 yr for B. lenta and S. albidum.