The resin and the damp in wood contains organic nutrients that enable the
lichen to establish themselves on the palings.
Joints, fissures and spaces between the many parts of the paling are excellent places for dirt and damp to accumulate –which supplies nutrition to the lichen.
And by that the growing speed and the affection's extent increases.
Constantly recurring affections by lichen will remain a problem as long as there are traces of spores or old lichen remains. They make additional sources of nutrition and the lichens ability to endure hard drought during long
time makes the affection very hard to prevent. All affection –both on the surface and in the pores- must be totally sanitized. The paling is by that disinfected in every little pore and fissure.