A debris blower for use in dispersing and collecting grass clippings, leaves, and other debris from sidewalks, driveways, lawns, golf courses and other ground surfaces. The debris blower is designed to be connected underneath a chassis of a tractor or lawn mower, and includes a housing containing a power-driven fan which rotates in a plane generally parallel to the ground surface. An air flow generated by the fan exits the housing through first and second chutes projecting from the housing. The chutes direct the air flow towards the ground surface. Air flow through the chutes is controlled by deflectors and closures that are moveable to selectively open and close the chutes and to adjust the direction of the exiting air flow.