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 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.
- 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.
- virus.
- cold soils, dry soils
- excessive liming
- may be more severe in spring than later in summer,
- cold, wet weather.
Manganese toxicity:
Often Confused With
Chemical:
Disease:
Soil & planting conditions:
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.