I can't find anything that indicates a specific allowance or denial of the dipped roses. However, the general information page on plants and plant clippings is found here:

https://help.cbp.gov/app/answers/detail/a_id/600

It also has a contact number at the bottom for permits and questions about things that are/are not allowed. I hope that the number can yield you some better information than the page, because even going through the aphis link did not give any info on roses or specific clippings from Peru. Good luck, that is a lovely looking item!

Oh yeah, the number listed is - (877) 770-5990 (toll free), (301) 851-2046 direct line.