Yes, they can send you to collections. Then, if you do not pay, the collections agency or the landlord could sue you to recover the money; that is the only way they force you to pay, if you refuse to do so--by suing you and proving in court (bya  "preponderance of the evidence," or that it is more likely than not) that you did  the damage and that it rises to the level of exceeding normal wear and tear.