Commentary for Avodah Zarah 90:6

R. Sheshet posits a different dispute. The dispute is over whether a tree that was first planted and then worshipped becomes prohibited or whether it is considered part of the mountain, and therefore cannot become prohibited. According to the first opinion, such a tree is permitted because it is part of the mountain, whereas R. Yose Hagalili holds that it is prohibited.

The rabbis who disagree with R. Yose son of R. Yehudah hold that if a tree is planted and only then worshipped, it is not prohibited. So they must read it is prohibiting only a tree that was planted for the express purpose of being an idolatrous tree.