You mean, like this? https://en.wikipedia.org/wiki/Luther_Burbank#Classical_plant... and https://en.wikipedia.org/wiki/Luther_Burbank#Intraspecific_b... ? Are you talking about specifically using "breed" (noun) to refer to a cultivar, or "breed" (verb) to refer to the process by which we obtain new cultivars/

Either way, the term is used colloquially throughout the US (and probably more) to refer to the industrial products of plant breeding.

It's common when talking about peppers since there are so many varieties of the same species. I guess cultivar, variety, and breed are mostly synonymous except that cultivar (to me) implies that human intervention was involved in the selecting. Variety can be used to mean the same thing but naturally without human intervention. And breed seems to be a more colloquial term that encompasses both of these.

I'm not entirely sure this is always accurate, but that is the distinction afaik.