--- a/src/fungal_effects.cpp
+++ b/src/fungal_effects.cpp
@@ -167,7 +167,7 @@
     } else if( m.has_flag( flag_YOUNG, p ) ) {
         if( x_in_y( growth * 10, 500 ) ) {
             if( m.get_field_intensity( p, fd_fungal_haze ) != 0 ) {
-                if( x_in_y( growth * 10, 800 ) ) { // young trees are vulnerable
+                if( x_in_y( growth * 10, 1600 ) ) { // young trees are vulnerable
                     m.ter_set( p, t_fungus );
                     if( gm.place_critter_at( mon_fungal_blossom, p ) && gm.u.sees( p ) ) {
                         add_msg( m_warning, _( "The young tree blooms forth into a fungal blossom!" ) );
@@ -183,7 +183,7 @@
     } else if( m.has_flag( flag_TREE, p ) ) {
         if( one_in( 10 ) ) {
             if( m.get_field_intensity( p, fd_fungal_haze ) != 0 ) {
-                if( x_in_y( growth * 10, 100 ) ) {
+                if( x_in_y( growth * 10, 2000 ) ) {
                     m.ter_set( p, t_fungus );
                     if( gm.place_critter_at( mon_fungal_blossom, p ) && gm.u.sees( p ) ) {
                         add_msg( m_warning, _( "The tree blooms forth into a fungal blossom!" ) );