Useful info - I found detailed instructions here on ordering disease free budwood from California’s Citrus Clonal Protection Program - http://www.fruitmentor.com/
When I posted the above question, they were out of bud wood. But it became available after a few months… If you call them and ask, the are very helpful and will let you know when it’ll be available next.
Does anyone know where I can get a Sumo Mandarin tree or Dekopon Mandarin tree or Shiranui Mandarin tree in Southern California? I can’t seem to find them anywhere. I’d be grateful for help.
at this point, your only option is to get a rootstock and graft your own with budwood from CCPP. I have no idea why Fourwinds is not offering this variety as it is clearly very popular.