diff --git a/ArduCopter/control_modes.pde b/ArduCopter/control_modes.pde
index 718bf26f63..3abcbbfa60 100644
--- a/ArduCopter/control_modes.pde
+++ b/ArduCopter/control_modes.pde
@@ -98,6 +98,7 @@ static void init_aux_switches()
         case AUX_SWITCH_RESETTOARMEDYAW:
         case AUX_SWITCH_SUPERSIMPLE_MODE:
         case AUX_SWITCH_ACRO_TRAINER:
+        case AUX_SWITCH_SPRAYER:
             do_aux_switch_function(g.ch7_option, ap_system.CH7_flag);
             break;
     }
@@ -109,6 +110,7 @@ static void init_aux_switches()
         case AUX_SWITCH_RESETTOARMEDYAW:
         case AUX_SWITCH_SUPERSIMPLE_MODE:
         case AUX_SWITCH_ACRO_TRAINER:
+        case AUX_SWITCH_SPRAYER:
             do_aux_switch_function(g.ch8_option, ap_system.CH8_flag);
             break;
     }
@@ -260,6 +262,12 @@ static void do_aux_switch_function(int8_t ch_function, uint8_t ch_flag)
                     g.acro_trainer = ACRO_TRAINER_LIMITED;
                     break;
             }
+
+#if SPRAYER == ENABLED
+        case AUX_SWITCH_SPRAYER:
+            sprayer.enable(ch_flag == AUX_SWITCH_HIGH);
+            break;
+#endif
     }
 }
 
diff --git a/ArduCopter/defines.h b/ArduCopter/defines.h
index 276dde24cc..2531bef954 100644
--- a/ArduCopter/defines.h
+++ b/ArduCopter/defines.h
@@ -66,6 +66,7 @@
 #define AUX_SWITCH_RESETTOARMEDYAW  12      // changes yaw to be same as when quad was armed
 #define AUX_SWITCH_SUPERSIMPLE_MODE 13      // change to simple mode in middle, super simple at top
 #define AUX_SWITCH_ACRO_TRAINER     14      // low = disabled, middle = leveled, high = leveled and limited
+#define AUX_SWITCH_SPRAYER          15      // enable/disable the crop sprayer
 
 // values used by the ap.ch7_opt and ap.ch8_opt flags
 #define AUX_SWITCH_LOW              0       // indicates auxiliar switch is in the low position (pwm <1200)