Do you notice a bad odor from your rooster’s beak? That white to yellowish material attached to his comb may be canker (trichmoniasis,) a protozoan infection spread by pigeons and wild birds. Or it could be a fungal/yeast infection. Canker stinks, but a yeast infection may not. Canker can be treated with certain drugs, such as metronidazole, ronidazole, acidified copper sulfate, or possibly with Thyme extract capsules. Fungal yeast infection may be treated with anti-fungal medicines such as Nystatin or Medistatin. Here is an article on canker:
https://poultrydvm.com/condition/canker
If possible, I would see a vet and ask about having them do a scraping of the material and looking at it under a microscope.
https://poultrydvm.com/condition/canker
If possible, I would see a vet and ask about having them do a scraping of the material and looking at it under a microscope.