Apricorns are used to make poke balls, various colors make various types of poke balls. The man who makes them is located in Azalea Town and his name is Kurt. It takes a day to make the pokeballs. The Apricorn Trees grow a new Apricorn every day.
List of Types of apricots and what poke balls they make.
Red Apricorn-Level Ball: If the pokemon you want to catch is lower level than your pokemon in field, it as a higher catch rate.
Yellow Apricorn-Moon Ball: Higher catch rate if the pokemon you want to catch evolves via Moon Stone, Nidorina, Nidorino, Jigglypuff Clefairy, ect.
Green Apricorn-Friend Ball: Sets the wild pokemon's happiness stat to 200.
Blue Apricorn-Lure Ball: Higher catch rate if the wild pokemon is a pokemon you encountered using a fishing rod.
Pink Apricorn-Love Ball: It has a higher catch rate if the pokemon you are using is the oppisite gender of the one you are trying to catch.
White Apricorn-Fast Ball: Has a higher catch rate if that wild pokemon can flee from battle, Abra, Enti, Ect.
Black Apricorn-Heavy Ball: It has a higher catch rate if the pokemon you want to catch weighs over 100 Kilograms (440 Grams).
You also can use Apricorns to Inprove their Performence stats, like stamina, power, skill, speed, by getting a Apricorn blender, which you can get at the pokeathlon Dome.