Methods and apparatus for applying substances to an area of interest

An apparatus for applying substances to an area of interest wherein the apparatus comprises:

• a. a plurality of sensors for sensing one of a plurality of sub-areas of the area of interest, each sensor generating a detection signal associated with a respective sub-area upon detection of a sub-area considered to have a chlorophyll intensity above a threshold level;
• b. a mode selector having a first state and a second state;
• c. a control circuit which produces a respective control signal associated with each detection signal, wherein the control circuit operates in a first mode when the mode selector is in the first state and a second mode when the mode selector is in the second state;
• and
• d. a plurality of outlets each associated with a respective one of the sensors, each responsive to the respective control signal from the control circuit and positioned to spray a substance on a sub-area associated with the respective one of the sensors;
• wherein the control circuit is operable in:
• i. the first mode to apply the respective control signal to each outlet to maintain it open except when the detection signal is present;
• and
• ii. the second mode to apply the respective control signal to each outlet to open it only when the detection signal is present.