The wood's resin and the damp in the wood have organic capabilities –which
gives the moss spores the nutrition it needs to establish growth.
Moss usually grows in fissures, joints and gaps on a paling, which is also where damp and dirt is accumulated on a fence. This provides the moss with even more nutrients. This enables the moss to grow fast and to get a strong foothold on the paling.
Growth of moss does not stop until every trace of spores or old mosses have been removed. This is done by sterilizing all spores and all mosses, the piling's surface and pores becomes disinfected –old and new affections and growths are guaranteed to be stopped for four years. Often longer than that.