Sensitivity of <i>Phaeomoniella chlamydospora</i> to fungicides <i>in vitro</i>

Abstract

Phaeomoniella chlamydospora has recently been shown to cause Petri vine decline in young grapevines No recommendations are available for management of the disease using fungicides In this study 22 fungicides were tested for their effect on the radial growth of three field isolates of P chlamydospora Systemic fungicides inhibited mycelial growth of the fungus at similar concentrations to those reported for other fungi The DMI fungicides cyproconazole bitertanol tebuconazole fenarimol myclobutanil and prochloraz gave EC₅₀ values for reduction of mycelial growth of less than 03 mg/litre whereas triforine gave an EC₅₀ value of 26 mg/litre For the benzimidazole fungicides benomyl carbendazim and thiophanate methyl the EC₅₀ values were less than 04 mg/litre For the anilopyrimidines pyrimethanil and cyprodinil/fludioxonil (Switch) EC₅₀ values were less than 002 mg/litre For the contact fungicides tested EC₅₀ values were higher than those reported for similar fungi The potential role of the fungicides in disease management is discussed