(a) The Mishnah discusses someone who weeds together with a Nochri, on his property among the Chasiyos - garlic, Lof, onions and leek.
(b) The Tana permits him to - eat from them Arai (casually).
(c) Despite the fact that the field belongs to a Nochri, he is not permitted to eat even 'K'va' (proper meals) - because this Tana holds 'Ein Kinyan le'Akum be'Eretz Yisrael Lehafki'a min ha'Ma'aser (a Nochri does not have a Kinyan in the field, to remove the Chiyuv of Ma'asros)'.
(a) The Mishnah rules that Gidulei Terumah Temei'ah that a Kohen planted - become Tahor.
(b) We are not afraid that he will therefore retain his Tamei Terumah until the planting season and plant it then, in order that it should become Tahor - because a. Terumah sells cheaply, and b. should it become Tamei, it will need to be burned. Consequently, he is unlikely to spoil his field by doing so (see also Tos- Yom-Tov).
(c) The Tana Kama requires him to cut away all that is ready to eat when it starts to grow, before being permitted to eat the rest. Rebbi Yehudah - requires him to do this a second time.