Abstract: The effects of acid rain on the susceptibility of Pinus massoniana to Lophodermium pinastri and Meloderma desmazierii were studied in several regions of Chongqing. The incidence of diseases was severer on trees in heavy acid rain areas. But, under conditions with pH<4.0, L.pinastri is inhibited. The percentage of needles covered with saprophytic fungi is much higher in heavy acid rain areas. Acid rain may be considered as one of the most important factors for the death of pinus massoniana in Manan of Chongqing.

Key words: Mycorrhizae, Desertification, Application of mycorrhizae