Manganese and Iron Chlorosis

Managing soils effectively to make essential micro-nutrients available for tree health.

One character of tree soils that can directly impact tree health is soil pH. The pH of the soil influences the ability of soils to release and or hold onto chemical nutrients that are needed for trees to live and be healthy. The measurement of pH is just the ability of soils to exchange hydrogen ions for other chemical elements.

Soils in the Minneapolis and Saint Paul metropolitan areas can vary significantly from yard to yard and region to region. It is not uncommon to find gradients in soil quality within the same landscape due to construction grading or the inversion of urban soils.

Most, if not all urban trees can prosper in soils with pH ranges from 6.7 to 7.2, where 7.0 is considered neutral Soils that are above 7 are considered alkaline and those below 7 are considered acidic. When soil pH increases above 7.5, there are fewer hydrogen ions to exchange with mineral elements. So soil particles, in essence, hold onto the elements tighter, making them unavailable for trees to acquire.

The key elements that get tied up by high pH soils are Iron (Fe) and Manganese (Mn). Deficiencies in these elements can result in chlorotic (yellowing) leaves due to reductions in the production of chlorophyll. Chlorophyll is required for photosynthesis. Trees with iron and manganese chlorosis cannot produce enough photosynthate to support their health and will begin to decline over time.

pH Sensitive trees:

• Red oak, Quercus rubra
• Northern and Eastern Pin Oak, Q. palustris, ellipsoides
• River Birch, Betula nigra
• Maples, Acer spp.
• Pines, Pinus spp.
• Spruce, Picea spp.

Management of Manganese & Iron Deficiencies

Rainbow Treecare can provide trees with iron and manganese to overcome the deficiency. Manganese and iron can be injected into the trunk of the tree for quick uptake via our M3 injection system. We prefer however, to apply the elements in tablet form to limit damage to trunk and root tissue. Although uptake is not as rapid, chlorosis can be decreased in a matter of weeks as the necessary elements are absorbed through the roots and transported to the leaves.

A soil test will help determine the pH of your soils. It will also provide us with information as to how we can best manage nutrient limitations that may result from soil conditions in your landscape.