Question: I bought Preen weed preventer and put it around the tree in my front yard, then I bought brown rubber mulch and put it around the tree. Now I have yellow dry substance on top of the brown rubber mulch which disappears when I put water on it but comes back and turns yellow again. Any suggestion on what this is and how to stop it. Thanks
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When singular and plural spellings differ, as in peony and peonies, try both.