Here we'll talk about what happens if a person's branches overhang his neighbor's property. The Mishnah says that some of these branches extend over the field of his neighbor. The neighbor is allowed to cut back overhanging branches that are lower than an ox goad. The height of an ox goad would be measured with a person standing on a plow and holding an ox goad, an instrument used to poke and prod an ox. If he was holding it up, anything below that would be considered a nuisance. It would be considered problematic, and therefore he would be allowed to cut that part of the branches down. He could trim them back. But he would have to leave alone any overhanging branches that are higher than that, even though they overhang his property.
But there are exceptions to this rule. This is the opinion of Tanna Kamma (first tanna). If we're talking about an overhanging tree that is either a Charuv tree, which is a carob tree, or a Shikmah, which is a sycamore tree, whose trees are very dense, with a lot of leaves, and prevent shade from going down onto the property below it, he is allowed to cut back all overhanging branches along the Mishkolet. The Mishkolet is the plumb line. When they were making a wall, they would make sure it was perfectly vertical using a sort of tool called a plumb line. This means that anything along the property line, the boundary of that field, is allowed to be cut back all the way in order to prevent the branches from blocking the sunlight that is needed. So overhanging branches of this type, which are very dense and totally prevent sunlight from coming down, are allowed to be taken down fully.
Beit HaShalchin kol ha-ilan keneged ha-mishkolet. And also with the Beit HaShalchin, which is a field that needs water, a field that needs irrigation, which is much drier than a regular field, the neighbor would be allowed to cut down overhanging branches if there are overhanging branches over that Beit HaShalchin. The neighbor could cut down all the overhanging branches along that plumb line as well, everything at the boundary of the field, because these overhanging branches are especially harmful in a Beit HaShalchin, because that field needs a lot of dew. It needs moisture, any moisture it can get from the sky. If there are branches on top blocking it, the moisture won't reach the ground. Therefore, you're allowed to cut down branches, even those higher than the mardea, that is, higher than the ox goad that a person would be holding up. You're even allowed to cut those back.
That was all according to the understanding of Tanna Kamma. Now we have a Tanna (Mishnaic sage) who disagrees about certain details here. Originally, we said that if a tree, whether fruit-bearing or not, was overhanging a person's property, anything above a raised ox goad would be allowed to be cut down. That's the opinion of Tanna Kamma. Again, that applies to both fruit-bearing and non-fruit-bearing trees. But Abba Shaul is going to disagree. Abba Shaul says that any type of tree that is just about shade, which is basically a non-fruit-bearing tree, is allowed to be cut back along the plumb line as well, even if its branches are higher than the raised ox goad. He says any branches in this type of tree are allowed to be cut back. According to him, removing these branches, which don't have any fruit on them, is not really a loss to the property owner. Therefore, the owner of the property that is being disrupted, the property being overhung, is allowed to trim back those branches. It doesn't matter how high they are; as long as they're not fruit-bearing, you're not causing anyone a loss, and you're allowed to trim them back.