משנה על פאה 7:1

One who thins out his olive-trees [in the seventh year]: Bet Shammai says: he cuts them down to the ground. Bet Hillel says: he may completely uproot them. They agree that if one levels his field, he can only cut them down to the ground. What is considered “thinning out”? One or two plants. And what is considered “leveling”? Three plants next to each other. This applies to his own property only, but from the property of another, even he that levels may uproot.

A vineyard of the fourth year Beth Shammai says: it is not subject to the law of the fifth nor to the law of removal. And Beth Hillel says: it is subject to the law of the fifth and to the law of removal. Beth Shammai says: it is subject to the law of fallen grapes and to the law of gleanings, and the poor redeem them for themselves. And Beth Hillel says: all of it goes to the winepress.