Hilchos Matnos Aniyim 4:20

Let’s say there’s a cluster of grapes on the branch of a vine and an underdeveloped cluster on a twig of the branch. If it can be harvested together with the cluster, it remains the property of the landowner; if not, it goes to the needy.

Hilchos Matnos Aniyim 4:21

If a vineyard is made up entirely of underdeveloped clusters, they all go to the needy as per Leviticus 19:10, “Do not gather the underdeveloped clusters of your vineyard.” The is true even if the entire vineyard is underdeveloped. Unlike the other gifts, peret and olelos are unique to vineyards.