If you read the article instead of the press release, you'll see that Soto's group showed that wheatgrass can be contaminated by hamster prions or CWD prions, but that they only showed transmission of hamster prions to hamsters through exposure to the contaminated wheatgrass. That's not cross-species transmission.

https://www.cell.com/cell-reports/abstract/S2211-1247(15)004...