This study presents results from a stand structure analysis of an energy forest plantation ofSalixviminalisL., clone 77-683. The stand, which was expected to contain only one clone, was shown to be composed of at least one male and one female clone. The male clone was susceptible toMelampsoraepiteaThüm. and displayed a larger proportion of frost damage after infection and lower mean size and weight than the uninfected clone. Regression analysis showed that the infected and uninfected shoots differed significantly in their size-weight relationships. Relative differences in size and damage between infected and uninfected stools were larger within the stand than along the border rows. The results illustrate how genetic differences in response to a pathogen can result in unevenly structured stands.