My browser isn't finding obligate in reference to elliptica, can you point me to which paragraph? I wouldn't extrapolate Albugo's being obligate to Botrytis deweyae. If you notice the preceding comment, it says that Botrytis cinerea (with which we're probably all familiar on other plants) is a necrotrophic generalist.
From: Molecular Phylogeny of the Plant Pathogenic Genus Botrytis and the Evolution of Host Specificity, Staats et al:
"Obligate parasites do not kill host cells but get their nutrients either by penetrating living cells or by establishing close contact with them. Necrotrophic pathogens such as Botrytis need to kill host cells before the cells are invaded by the fungus (Clark and Lorbeer 1976; van Baarlen, Staats, and van Kan 2004), which might suggest absence or a low degree of coevolution."
In the above they not only call Botrytis a necrotrophic pathogen but also a fungus. For most general horticultural purposes I would stick with fungus rather than oomycete - I think we're already getting a bit over our heads.
Re isolation of fungi from daylilies with spring sickness, that was done with the Aureobasidium microstictum study also.
Note I carefully covered myself by saying no MAJOR disease of daylilies other than rust is an obligate parasite. Daylilies do get viruses and those are obligate parasites but they aren't generally considered major daylily problems.
