Can one cut down branches of a fruit tree but not necessary cut down the entire the tree?
At what point does it become bal tashchis?
Is there no limit to trimming if it doesnt "kill" the tree?
As you are well aware, cutting down a fruit tree is subject to many prohibitions. You ask about pruning down which is more easily permissible.
ShulchanAruchHarav brings details here
Some Poskim rule it is forbidden to break a branch off from a fruit bearing tree [without one of the above-mentioned justifiable reasons]. Other Poskim however rule it is permitted to be done [in all cases]. Other Poskim are lenient for the sake of a Mitzvah.
Practically, one may be lenient for the sake of a Mitzvah through asking a gentile to cut it off. Thus, if one needs to cut branches for Sechach, Sukkah or Shavuos decorations, ideally one should cut the branches of a non-fruit bearing tree. If this is not available, then he is to ask a gentile to cut the branches.
It is permitted to prune branches off a fruit tree for the purpose of benefiting the health of the tree, so it grows healthy fruit, in accordance with the directives of a professional gardener. However, it is forbidden to prune the branches simply for beauty purposes, to beautify the tree. Furthermore, even when pruning for purposes of maintaining the health of the fruit tree, it is best for it to be done through a gentile, such as a gentile gardener, as stated above.
One whose neighbor’s tree is encroaching into one’s property, then if it is getting in the way of one’s use of the property. The same applies towards a privately-owned tree which encroaches onto the public pathway, that its branches may be cut to allow for smooth transit. Nonetheless, it is best to have the branches cut by a gentile, as stated above.
See the original for detailed references.
Beyond this there is a prohibition to prune a tree during the shmita year in Israel, except for the immediate upkeep of the three (see here).
OU Kosher here writes as follows:
There is a Biblical prohibition to cut down a fruit tree based on verses in Devarim (20:19-20). From the Talmud and poskim it emerges that there are several exemptions to this restriction.
The prohibition does not apply in any of the following situations:
- (a) the tree is old and no longer produces a kav of fruit (volume of 24 eggs)
- (b) the tree would be more valuable for its wood than as a fruit bearing tree
- (c) the tree is causing damage
- (d) the removal of the tree will allow for expansion of extremely cramped living space.
Nevertheless, Rav Yaakov Emden (1697-1776) in She’eilas Yaavetz 1:76 takes the dramatic position that, while there is no Biblical prohibition to remove the tree in the above situations, it is nonetheless a sakana (danger) to do so. Rav Yaakov Emden’s position has been intensely debated for the past three centuries (See Yabia Omer, YD 5:12, for sources).
Because there is a concern of sakana, many poskim recommend transferring ownership of the tree to a non-Jew, and then having a non-Jew remove the tree. While the allowance of having a non-Jew cut down the tree when the Biblical prohibition stands is also a matter of debate, one can allow a non-Jew to remove the tree when any of the four leniencies noted above apply. Pruning a fruit tree to improve productivity is also permitted.
This last point is mentioned in Darchei Teshuva 116:51. I saw that it writes here that the Darchei Teshuva stated above mentions that one can prune to enhance growth but also it is permissible to cut branches to meet any need or to fulfil a mitzvah, e.g., if the branches are hovering over a succah.