A rapid test to evaluate <i>in vitro</i> sensitivity of <i>Septoria tritici</i> to flutriafol, using a microtitre plate reader

Abstract

The sensitivity of Septoria tritici to the sterol biosynthesis inhibiting fungicide flutriafol was assessed using a quick and objective technique based on light absorbance to measure fungal growth. Microtitre plates were inoculated with suspensions of pycnidiospores taken directly from single pycnidia on leaves, after which glucose peptone broth containing different fungicide concentrations was added. After 10 days’ incubation in the dark at 17°C, growth was measured using a spectrophotometer at 405 nm. A dose‐response curve fitted to the absorbance data was used to estimate the fungicide concentration reducing absorbance by one half (EC 50 ). The method was precise, quick, reproducible and objective, with substantial advantages over conventional techniques.