Manganese Deficiency of Red Maple

In certain alkaline soil regions, the lack of available manganese can cause Red Maple foliage to turn yellow with brown areas followed, in some cases, by defoliation. The leaf symptoms (green veins with the interveinal tissue yellow) resemble the condition of iron deficiency of Pin Oak. Im more pronounced cases, the tissue between the veins turns brown, especially on the youngest or outermost foliage. The symptoms are most pronounced under the same soil conditions (moist with a pH above 6.5) as those which favor iron deficiency.

Since yellowing of the foliage is a common symptom on a number of landscape trees, a soil test and leaf tissue analysis are recommended prior to treating with any fertilizer. The proper diagnosis is important because maples treated with iron, rather than manganese, will cause the symptoms to become more severe, since iron further suppresses manganese uptake due to an iron-manganese antagonism.

Recent studies at The Ohio State University with Red Maple have shown that treatment with manganese compounds will help to restore the foliage to a more normal green color. The data in Table 1 indicate that trunk implantations of capsules of manganese citrate and two forms of manganese sulfate will improve foliage color and increase the chlorophyll content of Red Maple. Two of these compounds are still in experimental stages of development, however, the 78% Mn-SO₄ is on the market in capsule form as Mn Medicaps.

Manganese deficiency can also be prevented, although on a more temporary basis, by treatment with chelated manganese (Table 2). Foliar treatment with manganese sulfate is effective too. Both are commercially available.

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Typical manganese chlorosis of red maple.

Several chlorotic cultivars of Red Maple growing in a commercial nursery in a silt loam soil in central Ohio were sprayed twice (1 month apart) with chelated manganese in late summer to reduce the severity of the chlorosis. Definite regreening did take place. It was indicated by the increased total chlorophyll level of foliage of all trees sprayed. The recommended rate is 2 tablespoons of chelated manganese per gallon of water of disodium manganous ethylenediamine tetracetate dihydrate (sold as Sequestrene Na₂Mn).

In conclusion, if chlorosis of maples (particularly Red Maple) is observed with typical green veination, the cause is quite likely manganese deficiency. The soil should be tested and pH lowered if possible to a slightly acid range (6.0-6.5) for most permanent results. A foliar analysis will determine which mineral element(s) is causing the problem. In some cases, perhaps only a pH adjustment is necessary to control the chlorosis. In other instances, both pH adjustment and trunk implantation (foliar or soil) treatment with a manganese compound will be necessary.

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