Manganese
Manganese (Mn) is involved in photosynthesis and chlorophyll production. It helps activate enzymes involved in the distribution of growth regulators within the plant.
Identification
Deficiency
- Interveinal chlorosis extending from midrib to margin of leaves
- Relative wide bands around the major veins remain green, giving a “herringbone” pattern
- Symptoms first on older basal leaves
- Although the whole tree usually looks pale, the terminal leaves often appear greener
Toxicity:
- Peach is especially sensitive
- Can occur on soils with a low pH (pH 5.5 or lower)
- Brown spots or yellow mottled areas near leaf tips and along the leaf margins, usually develops on older leaves
- Brown spots may also develop on veins, petioles and stems,
- Bark of new shoots becomes necrotic, developing “measles”
- Growth is stunted
Often Confused With
Iron deficiency – interveinal chlorosis becoming almost white with only veins remaining green
Scouting Notes
Manganese deficiency may appear early in the season under excessive moisture conditions or cool slow growing conditions and later disappear. Like iron deficiency, it is more common in alkaline soils (pH is high), but it may be more severe on wet or poorly drained soils.
Management Notes
High applications of magnesium or phosphorous can induce manganese deficiency symptoms on soils that originally contained low levels of magnesium so avoid excess nutrient applications. Foliar sprays may be used but deficiency should be confirmed with tissue analyses before use.
