It is still called “rape” between farmers, because when we’re talking farmer-to-farmer, we know what we’re talking about.
When non-farmers are about, we’ll use the latin family name, “brassica.”
It is partly PC-ism, but saying “Wow, I got a bumper crop of rape!” in mixed, non-farming company causes a whole lot of people to whip their heads around, and that’s the fault of the non-farmers.
Rape (and other brassicas) are grown for more than just their seed, btw — some brassicas make excellent quick-growing graze for cattle, with excellent feed value.
Is Sudex a brassica?