A patch (10, 30, 40) or other device applied to a fruit or vegetable for releasing a gas, preferably ethylene, which accelerates maturation or which retards maturation, preferably carbon dioxide. The device attaches to a portion of the fruit or vegetable and releases the gas upon application or upon demand. Ripening or retardation is selective in a bunch of connected fruits such as bananas when applied to one finger, thereby providing selective ripening.