Ohia trees are dying rapidly, Why?

[Midnight Rambler]

The fungus attacks many different plants - the article mentions sweet potato and taro, which are about as closely related to each other as either is to ohia. It may be that it had not had the right conditions to jump to ohia before, or it may be a different strain that was recently introduced. Many fungi appear similar enough to be called a single species but slight genetic differences mean they attack different hosts, or affect those they attack differently.

For example, the strain of "ohia rust" that was introduced on infected eucalyptus a few years ago causes mild disease in ohia (it can kill small seedlings, but not adult trees), but is lethal to rose apple. There are other strains of the same fungus that are lethal to other trees in the same family.