To get any kind of accurate rust rating all plant conditions have to be exactly the same
as has been done in some university studies previously:
same soil, mineralization, same plant age, environment, fertilization, etc.
And rust ratings would have to be done at the same time.
I do my own "home gardener 1-5 rust ratings" but allow that there are big differences
between my 3 growing areas.
It would be nice if there were an official rust rating service where potential introductions could be sent for rust rating.
