More WHITE STUFF on my Hibiscus.

[Lyn W]

It says "BBC PLAYER ONLY WORKS IN THE U.K."

Sorry Ed, the white stuff was nymphs of woolly aphids and basically he said they are sap suckers but don't do enough damage to harm the tree's fruit or flowers so to do nothing and just brush wipe the branches when they've hibernated, but not to worry about it.
It's on BBC Gardeners World episode 27 if you can get to it somehow via google.

 

[BeeBee*BeeLeaves]

Thanks for the tips.
My soil is quite alkaline since this area is re claimed swampland from the 1960s and is built up of calcium, coral rocks, shells and sand.
It's raining right now. Shocking. But after it clears, I'm going to prune out most of the visible infestation and spray again.
Right now, saving this plant is important. But not as important as saving the rest of them.

Yes. The soil. Alkaline when hibiscus like it more acidic. That's where it begins. That's what has weakened your shrubs. Weak plants always attract pests, predators. Sometimes planting in raised beds helps, to control soil better, and hold on to amendments. Once soil condition gets better, plants are able to fight attackers. My farming experiences prove it every time. Soil that's alive allows nature to handle things.