Grass Allelopathy towards Trees?

Colorado Springs, CO(Zone 5a)

I had never heard that grass has something that will hurt or kill newly transplanted trees. I recently received several thuja Green Giants with a transcript of an article about turf grass and redbuds and pecans. First, I have never hear this before, has anyone else? Second, can this really be extrapolated to thujas? And third, a web search pulled up info about fertilized and watered turf grass, but I am dealing with native grass in a rural setting, so do I need to worry or will it be enough to pull out the grass from the soil I dig up and mulch after planting?

Thanks for any experience or knowledge in this area. I'm not an expert, but I know some of you are.

Dublin, CA(Zone 9a)

I've certainly seen the reverse where grass doesn't grow well under trees because of competition for water/nutrients and the shade that the tree provides once it gets large. If there is some bad effect on the tree, I don't think it's due to allelopathy, I think it's probably that people tend to water and fertilize to meet the needs of the lawn, and this will frequently not be the best combo of water/fertilizer for the tree. So in that sense a tree will probably do better if it's not in the middle of a lawn. But with your native grasses I would assume they don't get a lot of water and fertilizer either so I don't think you'll have trouble (after all, if you look out in nature, you can find trees growing in grassy meadows) But since I don't have a lawn this honestly isn't something I've ever looked into, so maybe there is something else that is happening.

Beatrice, NE(Zone 5b)

Some types of fescue exhibit allelopathy, but I've never heard of any native grasses that do.

Holland, OH(Zone 5b)

The issue of allelopathy is a good one. Black Walnut trees as ercrane3 says is a well know one. But even if a particular grass species doesn't have an allelopathic effect on a certain species of a tree or shrub, any plant growing where it will compete with the roots of another could inhibit growth just by stealing nutrients and moisture. In my Master Gardener class it was recommended that grass be kept at least three feet away from a new tree or shrub transplant for the first three years.

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