A boom for mounting to an agricultural sprayer comprises an elongate frame supporting a plurality of liquid application devices, liquid delivery means connected to the application devices, and an elongate tray attached to, and extending along, the boom. The tray is movable between a first position in which the tray extends substantially horizontally beneath one or more of the application devices to prevent material from leaking onto the ground below, and a second position in which the tray is located clear of delivery paths of the liquid application devices.