Correcting chlorosis is time consuming, expensive

This was posted originally at Indiana Living Green in June, 2008.

Red maple chlorosis. Photo courtesy Purdue University

Last fall, a tree company removed my 15-foot tall red maple that had been in the ground 12 years, yet failed to thrive.
It was tough losing the tree because it was planted to commemorate a special event.

However, each spring more and more leaves unfurled chartreuse with deep green veins, a condition called chlorosis. The chlorosis started in one section and continued to spread, affecting three-fourths of the tree’s foliage at the time it was taken down.

My soil tested a 7.5 pH, which is very alkaline. The higher the number, the more alkaline the soil. Most of central Indiana has alkaline soil, which is why rhododendrons and azaleas tend not to do well here.

Red maples (Acer rubrum), especially named cultivars, such as ‘October Glory’ and ‘Red Sunset’ that grow in alkaline soil are susceptible to a manganese deficiency. The alkalinity of the soil prevents the tree from taking up the nutrient manganese, which means the maple cannot produce chlorophyll, resulting in chartreuse leaves and stunted growth.

Pin oak (Quercus palustris); and river birch (Betula nigra); may react the same way when planted in alkaline soil, but their chlorosis is caused by an iron deficiency.

Without treatment, the chlorosis is fatal because each year, there is less and less chlorophyll to process light and air into nutrients.

Now that the tree is gone and the stump ground, there is a sunken place in the yard. Not to worry, says Jud Scott, a registered consulting arborist and founder and president of Vine & Branch, a Carmel, Ind., company that specializes in tree care and landscape design.

The sinking is a natural result of the decomposition of the roots. As they break down, they shrink, causing the ground to sink. The bigger the tree and root mass, the deeper the indentation, he said.

The cure is to add top soil to the area, a task you may have to repeat annually for a few years, depending on the size of the indentation. Or, you can dig out all the ground up roots, which look like mulch, and replace with soil.

You should avoid planting permanent plants, such as trees, shrubs or perennials, in the sunken area until the decomposition and sinking stop. You should also avoid planting the same kind of tree that you took down, especially if there was a problem such as with my red maple.

For more information about red maples, visit this Ohio State University Web site

It’s very difficult, time consuming and expensive to change the pH of the soil to correct the chlorosis. It usually takes some involvement by a certified arborist, especially if the tree is large.

These links may help:

• University of Illinois Extension
• Purdue University’s Plant & Pest Diagnostic Lab
• University of Wisconsin Extension
• Kansas State University Extension