From: Rabbi Moshe Sofer
To: Rabbi Hersh Kunitz
The Chasam Sofer disagrees with his student's proposed resolution of the Rambam's self-contradiction regarding kilayim and vineyard law. He argues that according to the Talmudic conclusion all Tannaim agree the plants are meant to be uprooted, and their dispute concerns only whether intent to uproot nullifies the kerem status; the halacha follows the Rabbanan that such planting does constitute a kerem, and one must rely on the Tosfos Yom Tov's resolution of the Rambam's contradiction.
Source: Shu"t Chasam Sofer CM §109