and Plant Nutrition Home
Form used by plants:
activator (decarboxylase, dehydrogenase, and oxidase enzymes)
iron in chlorophyll formation
CO2 in photosynthesis
for phosphorus and magnesium uptake
in chloroplast membrane (structure containing the high absorbing
chlorophyll pigment and C-assimilating mechanisms)
in N metabolism and assimilation
Ideal foliage range for apple leaves:
25-100 ppm leaf dry
Ideal fruit concentration:
Ideal soil range:
> 1.5 ppm
Deficiencies are most common on soils with
pH . 7.0. Toxicities may occur on acid soils.
Mn is relatively not mobile in soils.
Top of page
Mobility in plant:
Not remobilized within
developing in older leaves first. In
severe cases, heavy defoliation may occur.
Rust spots or a mottled pattern may be an indication on some
Increased risk of Mn deficiencies:
Availability of Mn
decreases as pH increases (at soil pH 6.3, Mn becomes insoluble)
Excess problems/Interactions with other
In acid soils, toxicity
may occur especially on Delicious and Jonathan apples.
Signs may include chlorosis,
early leaf abscission, reduced flower bud development, and internal bark
Excess iron, copper,
or zinc may reduce Mn absorption.
Excess sodium or
potassium may adversely affect Mn uptake.
Excess Mn encourages
updated: 14 February, 2001