Abstract
Populations of M. ligulicola [blight of Chrysanthemum morifolium] in the USA and in Great Britain, although morphologically identical, are distinctly different in reproductive response to long wave UV irradiation. Most American isolates require UV for induction of pycnidia; all British isolates tested produced pycnidia in total darkness. By following the historical distribution of M. ligulicola from its type locality into areas of differing cultural environment it is possible to account for the selection and proliferation of races of the fungus that differ markedly in response to environmental stimuli.

This publication has 1 reference indexed in Scilit: