Resistance to Mercury of Pyrenophora Avenae in New Zealand Seed Oats (Avena sativa L)

Abstract

Strains of H. avenae isolated form New Zealand seed oats were treated for resistance to mercury. Two samples of New Zealand seed oats (1 & 54) were treated with Agrosan 5W. The apparently resistant fungi 'R' (fungi growing form treated seeds) and apparently susceptible fungi 'S' (fungi growing from untreated seeds) were subcultured on to agar containing different concentrations of mercury compounds; inorganic mercurie chloride, organic phenyl-Hg-chloride and methoxyethyl-Hg-chloride. All strains isolated were able to grow on MEA containing high concentration of mercury (up to 125ppm Hg Cl 2 or 15ppm methoxyethyl-Hg-chloride) and some strains grew better in the presence of small amounts of mercury than they did in its absence. Of the three compounds used, phenyl-Hg-chloride was found to be the most effective in inhibiting growth of H. avenae. Growth of all strains of fungus was inhibited at concentrations above 0.075ppm phenyl-Hg-chloride.