I have a very large and old oak tree in a southwest corner of my yard. Last...

Asked October 18, 2013, 11:21 PM EDT

I have a very large and old oak tree in a southwest corner of my yard. Last year a ring developed in the grass in which all the grass died. We raked it this spring and fertilized and planted grass which did well until this last week. All the grass in this same ring died again. There are several mushrooms growing in this area of which I have removed about three times. Whatever can I do to keep grass going in this ring area? sheribetz1@aol.com

Eau Claire County Wisconsin trees and shrubs mushrooms oaks horticulture

1 Response

There are a few reasons that you may be having trouble growing grass in this area:

It is possible that the large old oak is beginning to die and the mushroom growth is a sign. Mushrooms themselves do not cause the death of grass but you will often see them form when there are rotting tree roots in the soil. They do not harm the living parts of the tree. The part of the mushroom plant that you can see (the caps) are just the "tip of the iceberg" so to speak. The largest part of the mushrooms are their roots - more properly called mycelium - that extend many feet, or yards under the soil. They do an important job by breaking down dead plant material and turning it into soil components.

Sometimes the fungus appears in a circle - often called a Fairy Ring. In this situation the mycelia are so active that the grass does suffer. While you can't get rid of the 'shrooms (they will reappear until all of the dead wood is consumed), you can rake up the dead grass and fruiting bodies of the mushrooms, de-thatch the soil and provide extra fertilizer.

This large tree may be providing too much shade for most grasses to grow well. Large trees also do a splendid job of out-competing other plants for water and nutrients. If shade isn't the main problem, it is possible that you need to provide extra water and fertilizer to the lawn in this area. You can also consider planting a ground cover that will be green, not need mowing and survive well in the shady conditions.

Here are some links that will give you more information and will provide some suggestions for alternative ground covers:
http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/p316fairyrings.html
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74100.html
http://www.extension.umn.edu/distribution/horticulture/components/08464-dry-soil-shade.pdf

I hope this information is helpful. Please contact AaE again if you have further questions.