Puccinia psidii

Puccinia psidii is a rust (a type of plant pathogen) native to Brazil with a very broad host range in the myrtle family (Myrtaceae). Puccinia psidii can have very serious consequences to various species of plants in the Myrtaceae. This family includes guava (the original host of this rust in Brazil), eucalyptus, melaleuca, and a number of species native to Hawaii, including some endemic species (found nowhere else on Earth) and at least one important native forest tree. There are numerous strains of the Puccinia psidii rust--some known to be established in Florida, and at least one reported from California--and it is feared by some concerned scientists that strains may exist--or could mutate into existence--that could be devastating to ohia (Metrosideros polymorpha), one of Hawaii's dominant native trees, a foundation species for many remaining Hawaiian native ecosystems. (This information is copied [with the permission of the author] from http://www.hear.org/species/puccinia_psidii/, the Puccinia psidii species information page from the Hawaiian Ecosystems at Risk project (HEAR).)