The Mishnah's law of Mechol HaKerem not only applies to a fence, but even if he made a line of posts that are positioned within three Tefachim of each other, they are viewed as a fence.

Question: Is this also true for standing crops and stalks; (or not,) as R. Chanina said, that if one makes a partition from a prohibited item (grain stalks) near his vineyard, it does not save...?

Suggestion: But R. Chanina therefore says that it does make a partition to prohibit planting between the vineyard and the fence, unless there is a gap of 12 Amos.

Question: (The Mishnah taught (Menachos 55 (f)) that R. Yehuda said - a Mechol HaKerem requires a separation of 12 Amos in the space between two vineyards.) It should be like a Karachas HaKerem and should require a separation of 16 Amos?

Answer (R. Yona): He requires 12 when there aren't two vines of two vineyards opposite each other (but rather they are staggered) so it doesn't look like a Karachas HaKerem of one vineyard. But if they would be opposite each other, he would require 16.

Question: According to the first Tanna, that a Mechol Hakerem is between a fence and a vineyard, does it only apply when it is fenced in from all four sides, or even if only on one side?

Answer: From the Mishnah that said that according to R. Yehuda, a Mechol is between two vineyards (even though the second vineyard doesn't surround the first), this shows that (also according to the first Tana) one fence is enough.

Question: Does the prohibition of Mechol apply (even if the fence only surrounds a part of that side of the vineyard or) only if it is along an entire side?

Answer (R. Zeira/ R. Yasa citing Rav Masnah): A large vineyard doesn't have a tail (if there is an extra vine protruding, it doesn't join the vineyard) and a small vineyard doesn't have a Mechol (space that is prohibited). A large vineyard doesn't have a tail, as a tail only has significance when it is needed to join two rows of two to total 5 vines. A small vineyard doesn't have a Mechol, otherwise the outside of it would be more stringent than the inside - inside it (between its rows), only 8 Amos would be prohibited and outside, 12 Amos would be prohibited. What is a small vineyard? 2 rows of 3. But if there were 3 rows of 3, (which is a 'large' vineyard) it requires a Mechol. (This implies that it requires a Mechol even if the fence is along the entire side.)

(R. Zeira): This shows that one may make posts opposite (only) 3 vines (and the rest can be without a partition).

(R. Yudan): If there are two fences (but there aren't 12 Amos between the vineyard and the first fence), if there are 3 Tefachim between the two fences, he may plant seeds there; if not, he may not plant.

(R. Yaakov bar Idi citing R. Shimon ben Lakish): If between a fence and a vineyard there was 12 Amos, the prohibition of Mechol has been removed.

(R. Chizkiyah): As long as it's 12 Amos along the entire length.

(R. Mana): It can even narrow off.