Omitting the Du'aa Qunoot

Q: Salaah-658: The Muqtadi has not yet started to recite the Du'aa Qunoot when the Imaam proceeded for Ruku. What should the Muqtadi do?

Answer: If the Muqtadi has not yet started to recite the Du'aa Qunoot when the Imaam proceeded for Ruku or if the Imaam forgets to recite the Du'aa Qunoot altogether, the Muqtadi should recite the Du'aa Qunoot if he is still able to join the Imaam in Ruku. If not, he should join the Imaam in Ruku without reciting it. And Allaah knows best what is most correct.

Fatawa Rahimiyyah vol.2