Answer: Moss or algae growing at the base of your tree indicates overly wet soil. Typically it does not kill trees, but wet roots can stress or even kill fruit trees. To get rid of the moss or algae, spray it with bordeaux (lime sulfur), available already to spray. Look in the fruit tree section of your garden center. Apply to your trees as instructed on the label. And, try to fix the drainage problem so water doesn't puddle around the trunk of your tree.
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