Hibiscus do very well in the Desert. They are both water and food hogs. That means they need deep water and then have the opportunity to dry out before the next water time. Summer is here, so daily water is the course. We prefer organic fertilizers as they are less likely to burn the plant - - something hibiscus are susceptible to as well. We like Down To Earth Acid Mix for the acid loving hibiscus. As to the 'white fungus', the issue is likely white fly. There was a heavy infestation throughout the Valley a few years back; it was very difficult to keep up with. That is no longer the case. White fly is difficult to eradicate but if you keep on top of treating the problem, you will get rid of it.
I have asked everyone about hibiscus out here and was told that they all succumb to a white fungus no matter what is done.
I'm sure they do carry and can answer all of your questions. I myself have never had luck with Hibiscus in this climate, so good luck.
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