I can imagine your ES experience Glen. I don't mind cleaning cat trays but when the spores are that bad it is really irksome. I was surprised at the ATP rating for JEDI SUE McCORD. It always has spores in my garden so it gets foliage ripped off heaps.
I realised how variable the responses can be even in a single cultivar when I saw that some research showed BARBARA MITCHELL as resistant but others as susceptible.
I think that susceptible is not a good term. It would be better to say 'non-resistant'. Maybe some cultivars have poorer immune systems than others.
