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2. Disowning the Shemita produce of one’s land:
Every person who owns a Kedushas Shemita product in his field must disown the product and give entrance for all people to be able to come and partake from the food.
Vegetables: Fields of vegetables which grew during the 6th year must be disowned during Shemita.
May the food be eaten if it was not disowned and was rather guarded from people?
How to be Mafkir the produce?
Some Poskim rule that the owner of the Shemita produce must disown it verbally. This is done by proclaiming in front of three people that the produce is Hefker. Other Poskim, however, rule there is no need to do so and the produce is considered automatically disowned. Some explain that although the produce is considered automatically ownerless, nonetheless, the owner is required to publicly disown it in order so people know that it is Hefker. Nonetheless, in their opinion, there is no need to disown it in front of three people following all the laws of Hefker.
Must one remove tithes from Shemita produce that was not disowned?
Some Poskim rule that all Shemita produce that was not disowned, as required by law, must have their tithes removed. Others rule that it is not necessary to tithe any Shemita produce even if it was not disowned. Practically the tithes are to be removed without a blessing.
 Rambam 4:24
 Rabbeinu Tam; Razah; Raavad
 Rashi; Rabbeinu Shimshon; Ramban; Rashba; Chinuch
 Ridbaz 4:4; Toras HaShemita 10:36
 Avkas Rochel 24; Derech Emuna 4:169
 See Shenas Sheva 4:22; Toras Ha’aretz; Halichos Hashevi’is [Oz Vehadar] in letter of Rav Shmuel Shtern
 See Letter of Rav Shtern ibid in response of Rav Chaim Kanievsky
 Beis Yosef
 Gra”ch Naah