Will This Stop Tropical Bugs from Killing My Plants?

I've been trying to figure out how to get rid of the black fungus on my Ixora. The flowers keep falling off because of all the ants, aphids and fungus that's sucking the life out of it. I planted this bush because I thought it was supposed to be indestructible.

A couple of days ago, the Honolulu Advertiser had an article about Dr. Bronner's Magic Soap. The advice was to mix the soap (1 part soap to 5 parts water) with water and spray your plants with it, both top and bottom of the leaves. UPDATE WARNING! (7-04-09) The 1 to 5 ratio was wrong. It killed my ginger flower and has nearly killed my Ixora.


You know....
It did kill the ants on our ginger plant. Sorry about the blurry photo.

We'll see how the suffering Ixora does in the coming days.

I've been reading up some more on the web about Dr. Bronner's Magic Soap and the Southern Nevada Water Authority says 2 Tbsp. Dr. Bronner's (Peppermint!) soap to 1 gallon of water. Wow! I've probably made my solution too strong. I hope it doesn't kill the plant. Well, if this is correct, it's certainly more economical.