Control effects of metalaxyl-M and azoxystrobin on stem and root rot pathogens of Hydrangea macrophylla

Abstract

The suppressive effects of metalaxyl-M and azoxystrobin against Pythium myriotylum, Globisporangium splendens, G. spinosum and an unidentified Globisporangium sp., which cause stem and root rot of Hydrangea macrophylla, were evaluated. The metalaxyl-M and azoxystrobin EC₅₀ values for the growth inhibition of the pathogens on potato-carrot agar were 0.02–0.12 ppm and 0.14–9.42 ppm, respectively. Soil treatments containing mixtures of metalaxyl-M and azoxystrobin showed significant inhibitory effects against the four pathogenic species.