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We have a Norwegian Maple tree in front of the house. But it has lots of moss in the branches, stem and in the ground.

Moss in branches

Moss in the ground

One of my neighbor said the tree is getting the moss from the ground. Last year we got the tree branches pruned so that there can be more air flow. Any tips or ideas on how to reduce the moss growth both on the ground and on the tree?

  • The moss is living with the tree and does not pose any danger to it's health. If you dry out the area to reduce the moss the tree will have less water too – kevinsky Nov 14 '17 at 11:05
  • The moss offers no water to the vascular system of the tree. They are not symbiotically connected. If allowed to harm the vascular system by allowing water to remain in contact with the bark the moss becomes...a parasite. Moss or mulch or rock or soil at the bottom of the trunk at the soil line will have the best chance in killing the tree by rotting the vascular system in a full circumference. Moss does not 'help' the tree at all. Not a big deal either. But in no way are they symbiotically connected. We are talking about rain water, humidity, north side drying slower than south side...? – stormy Nov 15 '17 at 4:56
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Moss is an opportunist. Spores are everywhere. The moss on the ground is not making the moss on the tree. Moisture (we must be looking at the north side of your tree, yes)? Is all moss needs.

I would scrape the moss off the tree...at least in the Y's between branches and trunk. Otherwise, I would not mess with the moss on the ground. Perhaps a thin layer (1") mulch of finely ground bark. Your neighbor is wrong that moss is 'catching'...if there are bare spots with constant moisture there will be moss. On trees, soil, bare spots in the lawn, north sides of homes...moss is not a problem, moisture is.

The base of the trunk looks healthy. I'd be more worried about moss thickly covering the base at the soil level as that will girdle and kill the entire tree. Looks just fine. If and when you cover with mulch make sure it is thin and does not touch that bark of the trunk. Any bark, rock, soil, moss, weeds up on your trunk can kill your tree...because they keep moisture on the bark, rotting it and next would be damaging the thin vascular system just below the bark.

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    do you have a reference for "I'd be more worried about moss thickly covering the base at the soil level as that will girdle and kill the entire tree" I have never read that. There are whole forests with moss everywhere and you don't see trees killed by moss – kevinsky Nov 14 '17 at 11:03
  • And those forests are used to more moisture than other forests. Cedars? There is a reason their wood is more resistant to moisture. Here we are dealing with cultivated species more at risk. I am not saying that his moss is a major problem...but at the base of the trunk and those Y's yes moss can be a problem. Have you been out gathering moss for hanging baskets to see all the damaged trees? Not just by moss, by age and normal rotting conditions. Yes one does see trees killed by moss, an errant landslide that covered the bark...but it isn't a big deal in the forest. At all... – stormy Nov 15 '17 at 5:01
  • Can you show me a reference to an article in a horticultural or arboriculture journal to back your claim? – kevinsky Nov 28 '17 at 10:56

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