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Ministry of Agriculture, Food and Rural Affairs

Manganese

Manganese is involved in photosynthesis and chlorophyll production. It helps activate enzymes involved in the distribution of growth regulators within the plant.

Identification

    • Deficiency causes yellowing between veins of young leaves,
    • Leaves gradually turn pale-green with darker green next to the veins,
    • Shows first at the growing tip on the young developing leaves which become bright yellow between the veins,
    • Veins remain green and the contrast between the dark-green veins and yellow interveinal area is striking,
    • If the deficiency is prolonged, the entire leaf assumes a dull-yellow appearance followed by premature leaf drop.

    Manganese toxicity:

      • Manganese toxicity can occur on soils with a low pH (pH 5.5 or lower)
      • It causes brown spots or yellow mottled areas near leaf tips and along the leaf margins and usually develops on older leaves,
      • Brown spots may also develop on veins, petioles and stems,
      • The bark of new shoots becomes necrotic, developing “measles”,
      • Growth is stunted.

      Often Confused With
      Chemical:

      • herbicides such as triazines (simazine, atrazine); ureas (diuron, linuron), uracil (terbacil, bromacil); dichlobenil, paraquat, fluazifop-butyl, oxadiazon,
      • high-very high phosphorus,
      • excessive magnesium on low manganese soils.

      Disease:

      • virus.

      Soil & planting conditions:

      • cold soils, dry soils
      • excessive liming

      Weather:

      • may be more severe in spring than later in summer,
      • cold, wet weather.

      Scouting Notes
      Manganese deficiency may appear early in the season under excessive moisture conditions and later disappear. It is more common when the soil pH is high.