Avodas Kochavim 4:12
If an animal that belongs to a resident of a condemned city was slaughtered, it is prohibited to derive benefit from it, the same way that it is prohibited to derive benefit from an ox that was sentenced to be stoned but that was slaughtered instead. One is permitted to benefit from the hair of both men and women of a condemned city but a wig is considered “its property” and is prohibited.
Avodas Kochavim 4:13
Produce that is still connected to the ground is permitted, as per Deuteronomy 13:17, “Gather… burn….” This includes only things that can be gathered and burned; it excludes produce that is still connected and would have to be harvested or picked in order to be burned. The same applies for hair (see previous halacha). The actual trees remain permitted and passed on to the heirs of the condemned.
If there is consecrated property in the condemned city, animals designated to be used as sacrifices must be left to die because “the sacrifices of the wicked are an abomination” (Proverbs 21:27). Property that was consecrated for use in the Beis HaMikdash must be redeemed and then burned. “Its property” (Deuteronomy 13:17) excludes consecrated items.