Publication no. D-2001-0723-01R

The Roles of Three Fungicides in the Epidemiology of Potato Late Blight. H. Mayton, G. A. Forbes, E. S. G. Mizubuti, and W. E. Fry, Department of Plant Pathology, Cornell University, Ithaca, NY 14853. Plant Dis. 85:1006-1012. Accepted for publication 6 June 2001. Copyright 2001 The American Phytopathological Society.

Three fungicides were tested in the field for efficacy on late blight caused by Phytophthora infestans. The effects of these fungicides on epidemic development, lesion growth rate and sporulation were measured. No fungicide completely arrested epidemic development under the environmental conditions of these experiments. However, the fungicide mixture, propamocarb hydrochloride plus chlorothalonil, had the most suppressive effect of the fungicides tested. The mechanism of effect included suppression of disease progress and lesion expansion. Growth chamber studies demonstrated that 24ºC compared to 10 or 16ºC limited cymoxanil efficacy.