Manganese and Magnesium in the Grey Speck Syndrome of Oats

Abstract

IT is generally recognized that the grey speck syndrome in oats is caused basically by manganese deficiency¹. Opinions differ, however, on whether grey speck symptoms are due directly to manganese deficiency^1–3, or whether manganese deficiency functions indirectly by rendering the roots of the plant more susceptible to infection by rhizosphere organisms the toxic products of which give rise to the visual symptoms⁴.