Sukkah 33: Disqualifying Berries

An existential question about mitzvot and if/when the items we use for mitzvot are disqualified from that use. Specifically, a myrtle branch, the top of which has been cut off. Can that disqualification be removed? (Even theoretically). But why would the berries disqualify the myrtle branch? (Blame the sense of beauty). Also, the question of timing: if diminishing the number of berries takes place before or after the myrtle is bound with the willow and lulav - when you reduce the number (before or after they're bound together) may make a difference. If something is disqualified from the outset, it is not permanently disqualified - and modification can make the difference. Plus, more on timing: can you diminish the number of berries on yom tov itself? In part, the answer may depend on your motivation for removing the berries. Which pushes us into the zone of Hilkhot Shabbat/Yom tov.