The present invention is a drone for spraying liquid such as pesticides, fungicides, herbicides, plant growth regulators, plant defoliators, and fertilizers over field crop. The drone comprises: a frame with a slender rigid beam in the middle and two base structures at the two ends, a rigid tube with an array of nozzles on elongated stems and the rigid tube is suspended below the beam structure with retractable wires, at least three propellers on motors with arms that are rotatably mounted to each of the two base structures of the frame, a power source positioned in one of the bases, at least one distance detector for measuring height of the drone above the ground, an antenna for sending and receiving communication signals, an electronic control system to operate motors and sensors, a container for a liquid material with a caped opening for refilling and an air pump to maintain a positive pressure in the container and electronic valve to allow liquid in the container under pressure to be released through a tr
