Physical
Control of Moss on Trees and Shrubs
Moss Control on Trees
In the Pacific Northwest, growth of mosses on trees and shrubs
around your property is often lush. Mosses on trees are almost
always accompanied by lichens. Fortunately, mosses and lichens
are generally not harmful to trees and often look attractive.
But, according to at least one source, wet mosses can be heavy
and making trees susceptible to wind damage (Rost,
1998). On the other hand, tree care businesses say they get
few requests for moss removal from trees and shrubs and that it
is rarely necessary.
Consider the underlying causes of prolific moss growth.
Generally mosses will be most developed on older landscape plantings
under conditions of diffuse light. With more direct sunlight
and air circulation around trees and shrubs, lichens are favored
instead of mosses. In areas with substantial air pollution, neither
lichens nor mosses are abundant.
If you want to change the mossiness
of your trees and shrubs, consider whether it is possible to change
the amount of direct sunlight. Increasing direct sunlight
may reduce moss growth but increased indirect light and diffuse
light may promote mosses. Please refer to other sections
of this web site, including Establishing
a Need for Control and Basic
Biology of Mosses for more information.
Physical Removal by Hand
The most common way to remove mosses from plants is by hand.
This is labor intensive and will only be effective on shrubs.
This is probably the best way to rid your shrubs of unwanted mosses.
It is wise to do this during the winter when the plant is dormant
so you do not damage active tree growth. You may do more
damage to buds than the mosses will do if you are not careful.
Power-washing
You may be able to remove mosses from trees and shrubs by using
a power washer to scour them away. This should be done in the
winter when a plant is dormant so you do not damage it with the
force of the water. Damage to buds even in the winter is an important
consideration. This method is not suitable for delicate plants
and may not prove too effective except on tree trunks and larger
branches that do not have developing shoots.