Related על תרומות 11:5

[With respect to terumah] olive pits, date pits, and carob pits, all of them -- even though they are not gathered up (i.e., they become planted in the ground unintentionally) -- are forbidden [for consumption by non-Kohanim]. And the remainder of all the [terumah] pits that are gathered are [also] forbidden, as nothing [of terumah] that is gathered is permitted [to non-Kohanim].

Just as they forbade consumption of terumah, so too did they forbid [consumption of] untithed produce and of tithes taken from untithed produce, and of first tithe, so that one would not carry his terumah or second tithe or consecrated produce that was not redeemed.