Despite last year's wonderful flower show, my Rose Mallow hibiscus is not doing so well right now. After soaking the branches in insecticidal soap (potassium salts) to remedy a sawfly infestation, each bud has turned black and died. I don't know if the buds were affected by the soap, or if there is a fungal infection (like botrytis?) going on. I don't know enough about diseases to make a judgment. My biggest concern: is it salvageable? I greatly appreciate any advice.
I'd call this "failure to thrive":
The buds that never were:
A black bud, with a little white on it (fungus?):
In case you were wondering what sawfly larvae damage looks like:
And a bonus! A very sad delphinium. Any ideas what's wrong with this one?: