Here’s a little information I got from our distiller regarding Barley:
As for barley: there are two kinds, 6-row and 2-row. There is hardly any 6-row grown any more, most everyone is switching to 2-row. I believe that back in the day 6 was considered “better” but there has been so much work on 2-row that it’s the predominant one now. One of the issues with 6-row is that the heads are so heavy, they can cause the plant to fall over in the field (called “lodging”) which obviously ruins the grain.
So we get essentially 100% 2-row. There are different strains (Thoroughbred, Cascade, loads of others) that have been bred to be better for malting. Growers can manage the crop to influence that too.
It used to be that the malting companies produced primarily for the brewing industry and we got the leftovers. (Fred Noe told me once “we get the floor sweepins”)
Nowadays though, they are giving us a lot more attention and really working to get us the performance we need. Note that there is no GMO barley out there.