The Torah presents this prohibition in the context of warfare: even when Israelite soldiers lay siege to an enemy city, they may not uproot or destroy its fruit trees, as it says: “When you besiege a city for many days, waging war against it to capture it, you shall not destroy its trees by wielding an axe against them; you may eat from them, but you shall not cut them down. Are the trees of the field human beings, that they can withdraw before you into the besieged city?” (Devarim 20:19).
Ramban explains that the prohibition was addressed specifically to soldiers because the turmoil of war can awaken an impulse toward vengeance and destruction; they therefore needed a special warning not to destroy fruit trees. This mitzva also expresses faith that God will grant success to our soldiers: there is no reason to destroy the fruit trees, for after the war those trees will be ours. According to Ramban, the prohibition applies only in Eretz Yisrael and in places Israel intends to settle, and there is therefore also a mitzva to eat from the fruit of those trees during the siege (Ramban to Devarim 20:19; Ramban, Additions to Rambam’s Sefer ha-Mitzvot, positive commandment 6). Most poskim, however, understand that the prohibition against uprooting a fruit tree applies everywhere in the world.
When fruit trees are needed for the siege, they may be uprooted. The Torah teaches that one must first uproot non-fruit-bearing trees, and only if the non-fruit-bearing trees are insufficient for the needs of the siege may one uproot fruit trees as well (Bava Kama 91b). Rambam explains that the primary prohibition is to destroy fruit trees in order to distress those under siege and cause them anguish when they see their trees being uprooted. [1]
The prohibition against uprooting a tree also applies when one blocks the irrigation channel that waters it, since this is one of the normal ways of destroying a tree. However, one is liable to lashes only when he destroys the tree with an axe or the like, as it says, “You shall not destroy its tree by wielding an axe against it.” By contrast, one who blocks the irrigation channel violates a Torah prohibition but is not liable to lashes.
Only damaging the irrigation channel or the piping that brings water to the tree is prohibited by Torah law. One who merely stops watering the tree, however, does not violate the prohibition of destruction, even though the tree will die on its own, for a person is not obligated to keep a tree watered. Still, it is the way of the righteous to make the effort to preserve things that benefit life, when the benefit is worth the effort. [2]
[1]. This is Rambam’s formulation in Sefer ha-Mitzvot, negative commandment 57. Some maintain that during a siege the prohibition is more severe (Smag, negative commandments 229; Leḥem Mishneh to MT, Laws of Kings and Wars 6:8; R. Goren, Torat ha-Mo’adim). Nevertheless, when life is at stake, one may uproot trees even during a siege in order to distress those under siege. Others maintain that the prohibition applies only when the purpose is to distress those under siege; but if the purpose is to help the siege effort, then even when life is not at stake it is permitted (R. Waldenberg, Hilkhot Medina 2:7). Most poskim maintain that there is no difference between a siege and any other situation. The Torah teaches that during a siege one must first use non-fruit-bearing trees; but if there is a need to use fruit trees, then since the purpose is victory and not destruction for its own sake, it is permitted, as we learned in Bava Kama 91b and in Sifrei to Devarim 20:19. This is also the position of Rashi, Ramban, Meiri, and others.
[2]. Rambam writes that blocking the irrigation channel is also prohibited by Torah law (MT, Laws of Kings and Wars 6:8). Ha’amek Davar and Maharsham explain that one is liable to lashes when he damages the tree with an axe, whereas for an act that kills the tree indirectly, such as cutting off its irrigation channel, he is not liable to lashes. Clearly, a person is not obligated to water a tree – unlike his obligation toward another person, regarding whom the Torah says, “Do not stand idly by the blood of your fellow” (Vayikra 19:16). Therefore, even if there is an automatic irrigation system, one may turn it off so that water no longer flows to the trees, since this does not damage the pipes that sustain the tree. Ḥazon Ish writes similarly in his comments to this passage. He adds that preserving the tree is an act of piety, for “the property of the righteous is dearer to them than their bodies,” because they are careful to avoid theft (Sota 12a). Similarly, Minḥat Yitzḥak 3:45 writes that a person is not required to eat ordinary bread when he has better bread available; as long as he does not perform an act that directly or indirectly causes the food to be destroyed, there is no prohibition.
