Effect of Anthracnose on Growth of Grafted Black Walnut. Michael N. Todhunter, Research Geneticist, International Paper Company, Southlands Experimental Forest, Box 571, Bainbridge, GA 31717. Walter F. Beineke, Associate Professor of Forest Genetics, Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907. Plant Dis. 68:203-204. Accepted for publication 26 August 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-203.

Black walnut (Juglans nigra) may be defoliated during the growing season by anthracnose caused by Gnomonia leptostyla, and growth of defoliated trees has been assumed to be reduced. Over a 5-yr period, however, grafted black walnut from 94 clones at Purdue University showed no significant correlation between degree of anthracnose infection and height or volume growth. A very low, but significant, correlation was found between anthracnose incidence and diameter growth, perhaps because diameter growth continues later in the season than height growth and could be affected by early defoliation.