Hello, I want to know if you can clear up some confusion for me. I have some moss growing on a couple of my trees,and on the north side of my house. A friend told me to spray them with Copper Sulfate. I searched and could not find a liquid form. Someone at the local nursery told me Round Up will do the same thing. What is your suggestion? Will either of these harm the trees? Thanks for any help!

You have 2 different things here. First, the sidning can be cleaned with a pressure sprayer using a cleaner labelled for the type of siding you have. Look for a product that is non-toxic to plants. Before using, cover nearby plants or wet them with water. Keep them wet with fresh water, and rinse them thoroughly when finisihed with the cleaning. Check locally for an algae inhibiting cleaner.

The algae is a result of high humidity and excess moisture. Sometimes a little judicial pruning can help. Pruning low-hanging branches may help, maintaining clearance around the hose, and providing for good air flow can cut down on the algae and moss problem.

The trees are not really a problem. I don’t recommend using any tyupe of cleaner or other product on them. Copper is deadly to plants, if enough is applied, and you should avoid using it. The trees are not harmed by moss or algae on the bark. It is a natural ococcurrence. If you feel you need to remove some from the tree, use a strong stream of water from a hose—NOT a pressure sprayer. Don’t use any chemicals or cleaners, just water. A plastic brush used lightly is OK if the tree has thick rough bark.