Daf Yomi - Sukkah 17 - Asheira

The Minchas Chinuch wonders what would be the halacha if one covered portions of his sukkah with s'chach from an asheira tree. He states that it certainly ineligible to be used for s'chach for it is scheduled to be burned and that minimizes it's measurement to nothing. However, he is in doubt as to what is its status. Is it like invalid s'chach and therefore it would disqualify the sukkah with four tefachim or is it like open space and then it would invalidate the sukkah with merely three tefachim. He leans toward the logic that it is not deemed as open space, rather as dirt or ashes. However, he claims that we might not be able to apply the principle of dofan akumah here. According to the Rishonim who maintain that dofan akumah accomplishes that the invalid s'chach becomes part of the wall, we cannot apply dofan akumah by avoda zora because the asheira branches will be disqualified from being a wall as well.