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Hibiscus as a source of allergies?

Hibiscus out here in the sunny West are common landscape plants...the red ones are usually less winter hardy than the other colors for some odd reason.... I’ve seen this many a time too. In San Luis Obispo where I live, and especially in Los Angeles and San Diego, they are preyed on by the silverleaf whitefly (Bemisia argentifolii); almost every single hibiscus in some areas.... and it is triggering some bad allergy problems too. This whitefly has also invaded large parts of Florida. Because so many whiteflies get on the hibiscus plant, millions of them, they secrete loads of "honeydew" (a sticky excretory waste that is mostly plant sugars) and then sooty mold grows all over this. The end result is a sick shrub that is daily producing an incredible amount of mold spores and insect dander, both of which are highly allergenic. (As the whiteflies die or simply undergo metamorphosis, lots of insect dander is produced.)
By the way, hibiscus (sometimes with the same whitefly problems) are often used as houseplants, and an infested plant like this inside your house is a surefire way to get sick.
I usually advise people to hose down their buggy landscape hibiscus hard, very hard, to knock off as many of the pests as possible, and then to prune the entire plants back hard, to about two feet or less in height. Words of warning though for those with allergies, wear a facemask when you hose down one of these! Insect dander and mold spores will be thick in the air as you do this.
They should then start spraying what's left of the shrub with fungicide and insecticide. This species of whitefly has developed considerable resistance to most chemical insecticides. Instead, use a soap, vegetable oil and water spray with several tablespoons of baking soda added per gallon for a safe insecticide/fungicide. (For each gallon of spray use up to 5 tablespoonfuls of dish soap and 3 spoonfuls of any kind of vegetable oil.) If this doesn't do the trick after repeated sprayings (and often it doesn't) then the advice from here is to shovel prune the offending hibiscus.
A friend of mine, a nice guy but not a very good gardener, asked me recently what I meant by shovel pruning roses. We were in my back yard, working in a bed of roses. I picked out a rose bush that had always been quick to get rust and mildew and slow to flower, put the shovel to it, dug it up and tossed it in the trash can. "That," I told him, "is what the rosarians call shovel pruning."
"Oh," he said, and seemed impressed, "now I get it."