In a new spraying apparatus the spray dispensers for liquid or finely divided spray material discharge into an enclosure contained within a flexible skirt attached to a sprayer boom. Air under pressure is injected into the skirt which supports the boom from the ground as it is moved over the area to be sprayed. The skirt is formed by one or more flexible air bags into which the air is injected and from which it escapes into the skirt enclosure. An annular air bag skirt structure is formed by folding inwards the edges of a strip of flexible material and fastening them to the strip in spaced parallel relation to form two parallel tubular passages. The open ends are then closed by means of respective open-sided envelopes slipped over the ends and laced thereto.