Ok, got it. You are asking specifically about the Gossard 2015 plants. If you go to his website and read the introduction information you will see a comment about rust resistance.
http://www.daylilynet.com/
My best guess is that when someone edited the data for those plants they put the rust rating in the database as well. Anyone can change the rust rating of a plant in the ATP database by using the pull down box wen editing data. How accurate this makes any of the rust ratings in the database is debatable.
Someone must have entered the data from his website, the AHS registration info is not allowed to be posted until the 2015 checklist is printed.
