The wooden fibres, the damp and the resin contain organic substances –which
gives nutrition to the lichen. The affection gets the nutrition it needs
–especially on raw wooden surfaces- and the affections becomes
sever.
On the wooden surface damp and dirt accumulates and contains nutrition
–the affections is by then established and very hard to get rid
of.
The spores establish themselves fast and when the lichen has developed
its thread system –the mycelia- they grow even faster. The growth
and the affections must be
sanitized –the lichen must be sterilized and the surface must
be disinfected.