Calquat fruit can be grown at level 72 Farming on a calquat tree. While inedible, they can be hollowed out with a knife to make Calquat kegs, which can hold up to four pints of player-brewed ale. Calquats can also be used in a Compost Bin to make supercompost. Picking the fruit gives 48.5 experience, with 6 fruits per tree, when fully grown.
Despite being inedible to players, calquat fruit can be fed to white Broodoo victims during the Tai Bwo Wannai Cleanup minigame, dealing high damage. Calquat fruit is convenient to use for this purpose if you have the requisite 72 farming level to plant a calquat tree in the Tai Bwo Wannai farming patch.