I can't think of any legitimate grower that doesn't understand the importance of maintaining a disease free collection.
That is a distinct benefit of being a registered nursery. The stock is inspected regularly by a state 'Plant Specialist' and there is immediate, free access to the state plant path lab should a problem arise.
Being realistic about the possibilities of infections from sources other than lilies, we continually sanitize everything from shears to the tables to the liners of ponds between plantings. There are chemicals available that I've mentioned in the past that are as effective as bleach and less damaging to the plants and environments.
In addition, since some Phytophthora are known have host plants ( I think the list for P. ramorum is approaching 200 known hosts), I assume all plants in and around Nymphaea are suspect as carriers, so prophylatic measures are always in place.
Lately I've been playing with biofungicides to see if they are effective in saturated soils...either solo or in combination with synergistic chemical fungicides and the results look promising.
Finally, I am getting closer to be a "closed' nursery...part of the reason I don't do open trades with unknown partners.
Are my efforts effective? I have never once had a plant path report come back on a lily showing the existence of crown rot, so I have to say yes. And that is without harsh disinfective treatments and a year plus isolation.
If you are interested intrying any of my protocols....just ask.
Truth is not what you want it to be; it is what it is. And you must bend to its power or live a lie.”― Miyamoto Musashi
"Knowledge speaks, but wisdom listens." ~ Jimi Hendrix
“The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge.”― Stephen Hawking
Craig