An investigation was conducted into whether fungal dynamics are determined by the balance between colonization and fructification, both of which are controlled by climatic factors, particularly rainfall. The distribution of Lophodermium pinastri on Pinus sylvestris needles was studied along two altitude transects over two successive years. Annual rainfall increased in a similar way along the two transects. Colonization (black zones) and the presence of fruiting bodies (ascomata and/ or conidiomata) were observed. Both increased with altitude. At low altitude, needles bore black lines only. The number of needles bearing fruiting bodies increased at altitudes above 1000 m and were present on all needles at high altitude. Empirical and dynamic mathematical models were developed and evaluated in relation to rainfall, assuming that spore production correlates with fructification, and colonization to spore dispersal.