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Name: Susan
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Can you tell me what is causing lichen to grow on all my tress, from crab apple to spruce, and how can I get rid of it???

"Attempts to remove lichens are rarely successful."

Anthony Brach Ph.D.


The fact that lichen is growing in your area shows that both:
1. there is a source bringing this symbiosis between an agla (plural algae) and a fungus (plural fungi) in contact with your trees
2. conditions are good for the growth and development of the lichen.

I would answer your question with a question: Why do you want to get rid of the lichen?

There is no real reason to do so....the lichen will not harm the trees on which it is is basically just using the trunk of the tree as a place to live. The symbiosis of the alga and fungus means the lichen survives via the photosynthesizing capability of the alga, and the fungus gets what it needs from the symbiosis.

I have several trees along the road in front of my house, and I was observing the lichen growing upon them the other day. I planted the trees 15 years ago, and I was pleased to see that what once was a former farmer's field, then covered with weeds of all types, was now an environment in miniature.....the lichen had found a satisfactory place to grow and develop, and the tree is simply providing a place to do that.

Summarizing, the development and success of an organism in an area depends first on something bringing the organism to the area, and secondly, the provision of a suitable environment for survival. If the process were to be interrupted (which, again, I don't recommend), it could be done by stopping one of these two functions. Adjacent (nearby) forests/trees where lichen is on the trunks could be leveled and destroyed. The environment could be altered to make it less suitable for growth of the lichens; a thinner canopy with more penetrating sunlight and less moisture would do the trick. Conceivably, the lichen could even be removed by abrading it from the trunks of the trees, but this could certainly damage the bark and potentially create a infection port for harmful organisms, namely insects and/or pathogenic (disease-causing) fungi.

My opinion: leave well enough alone, and enjoy the development of an environment (the lichen) in an environment (the tree trunk) in the big environment we call nature.

Thanks for using NEWTON!

Ric Rupnik

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