“When you siege a city many days to wage war against it, to seize it, do not destroy its trees – by swinging an ax against then – because from them you will eat. And you should not cut then down. Is the tree of the field a person that it will enter into siege before you?” (Devarim 20:19)
The Torah includes various laws that regulate the waging of war. One of these laws is presented in the above passage. When we lay siege to a city, we are not permitted to destroy the fruit-bearing trees that in the countryside surrounding the city. The passage is somewhat vague in its explanation for this prohibition. Sforno, Nachmanides and others explain that the prohibition reflects our confidence in the ultimate outcome of the campaign. How is this confidence represented by this law? We are not permitted to destroy the fruit-bearing tress because we will be successful in our efforts to conquer this territory and we do not want to take possession of a territory that we have ravaged. We will want to take advantage of the territories productive resources. Therefore, in waging war we must take care to protect the resources of the territory. We will benefit from our restraint when we ultimately triumph in our efforts.
This passage explicitly prohibits the destruction of fruit-bearing trees when waging war. However, Sefer HaChinuch explains that this mitzvah also prohibits any unjustified destruction of fruit-bearing trees. In addition, this mitzvah does not only prohibit the destruction of fruit-bearing trees. It also extends to the destruction of any object of utility. It is prohibited to destroy vessels, clothing or food. Sefer HaChinuch relies on Maimonides for this ruling. Sefer HaChinuch posits that the general prohibition against destroying fruit-bearing trees and other objects of utility is included in this mitzvah on a Torah level. In other words, although the passage only mentions the destruction of fruit-bearing trees in the course of waging war, the destruction of these trees at other times and the destruction of other objects of utility is included in the Torah’s prohibition. Others argue that this is not Maimonides’ positions. They contend that the Torah level prohibition only includes the destruction of fruit-bearing trees. The destruction of other objects of utility is included in the commandment on a Rabbinic level. In other words, the Torah does not prohibit the destruction of the objects. The Sages formulated this prohibition as an extension of the Torah’s prohibition against the destruction of fruit-bearing trees.
There is a strong basis for this second position. Maimonides comments that the punishment for the violation of this commandment is lashes. However, he also notes that this punishment is reserved for instances in which a fruit-bearing tree is destroyed. If any other object of utility is destroyed, lashes are not administered. This seems to support the position that the destruction of these other objects is a Rabbinic injunction. Like other Rabbinic injunction, no lashes are administered for its violations.
However, Sefer HaChinuch responds to this argument. He explains that in order for lashes to be administered for the violation of a mitzvah, the prohibition must be clearly stated in the Written Torah and not merely included in the Oral Law. The passage above only refers to the destruction of fruit-bearing trees. The inclusion of other objects of utility is based on the Oral Law. There is not clear reference to this inclusion in the Written Law. Therefore, although the Torah law includes all objects of utility, lashes can only be administered for the destruction of fruit-bearing trees.
Maimonides explains that it is permitted to destroy a tree that is not of a fruit-bearing species. Similarly, it is permitted to destroy a tree that is of a fruit-bearing species but is too old or unhealthy to yield an amount of fruit worthy of harvest.
This law seems to contradict Maimonides’ ruling regarding the destruction of objects of utility. As mentioned above, Sefer HaChinuch contends that this prohibition is included in the mitzvah on a Torah level. Maimonides explains that this prohibition includes the destruction of food. However, he seems to indicate that the destruction of any amount of food is prohibited. We can assume that Maimonides would acknowledge that the amount must be useable to be included in the prohibition. But clearly even an unhealthy tree or old tree will produce a useable amount of fruit. True, it may not be practical to harvest this amount of fruit. But the fruit is still of use. So, as long as the tree can bear a usable amount of fruit, why can it be destroyed?
In order to answer this question, it must be recognized that there are two approaches to understanding the prohibition against destroying fruit-bearing trees. The simple explanation is that the tree is of importance and significance because of the fruit it bears and will bear in the future. Because it is prohibited to destroy the fruit, it is also prohibited to destroy the tree that bears and will bear the fruit. In other words, the primary prohibition included in the mitzvah is the destruction of fruit or food. The passage tells us that even the tree that will produce the fruit cannot be destroyed. This seems to be the position of Sifrei.
The alternative approach is that the destruction of a fruit-bearing tree is not a secondary prohibition. Such an act of destruction is inherently prohibited. It is prohibited to destroy a resource. The destruction of this resource is not prohibited simply because of the product that it will produce. The very status of the tree as a useful resource creates a prohibition against its destruction.
What is the practical difference between these two approaches? According to the first approach, it will only be permitted to destroy a fruit-bearing tree if it can no longer produce an amount of fruit that is of significance. Whether a person would actually trouble oneself to harvest this small amount of fruit is irrelevant. But according to the second approach, the tree must be evaluated as a resource of value. If it is no longer a resource of value, then it can be destroyed. True, the fruit is will bear may be of some utility. But the tree must be evaluated as a useful resource – a tree that will be harvested. If it is not worthy of harvesting, it is no longer a useful resource and it can be destroyed. This seems to be Maimonides’ position.
In other words, according to Maimonides, the specific definition of destruction differs from object to object. In each case, halacha considers the utility of the object or its general purpose. In the case of food, any amount that can reasonably be eaten cannot be destroyed. This is because food is designated for eating. If it will be eaten it cannot be destroyed. But a fruit-bearing tree also has a purpose or utility. It is a resource. Its purpose is to provide an amount of food that is worthy of harvesting. No one plants a tree for a single fruit. The planter’s intent is to nurture a resource that will bear a harvest of fruit. Once the tree can no longer serve this purpose, it has lost its utility and can be destroyed. Rabbaynu Ovadia Sforno, Commentary on Sefer Devarim, 20:19. Rabbaynu Moshe ben Nachman (Ramban / Nachmanides), Commentary on Sefer DEvarim 20:19.  Rav Aharon HaLeyve, Sefer HaChinuch, Mitzvah 529.  Rav Yehudah Rosanes, Mishne Le’Melech, Hilchot Melachim 6:9.  Rabbaynu Moshe ben Maimon (Rambam / Maimonides) Mishne Torah, Hilchot Melachim 6:10.  Rav Aharon HaLeyve, Sefer HaChinuch, Mitzvah 529.  Rabbaynu Moshe ben Maimon (Rambam / Maimonides) Mishne Torah, Hilchot Melachim 6:9.  Sifrei Parshat Shoftim, chapter 60.