11-26-2010, 04:50 AM
At our elevation of about 1000 feet, plumeria gets a red rust fungus. It's pretty much inevitable up here and we've sold almost all of our named collection (one to go, Candy Stripe, if anyone is interested). I don't know that washing will have much effect for very long. If you are diligent and repeat every week or two, especially during rainy periods, relatively mild horticultural sulfur, about a tablespoon to a gallon, can be used to control rusts. Especially spray on the underside of the leaves. If the plants are dense and overgrown, some pruning to open then up to the air is helpful. Sulfur will also control the mite that causes the leaf galling on many hibiscus varieties. Don't know about the puakenikeni. Our trees don't show any diseases at all.