Puccinia psidii is a rust

Rust (fungus)

Rusts are plant diseases caused by pathogenic fungi of the order Pucciniales. About 7800 species are known. Rusts can affect a variety of plants; leaves, stems, fruits and seeds. Rust is most commonly seen as coloured powder, composed off tiny aeciospores which land on vegetation producing...

 (a type of plant pathogen) native to Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

 with a very broad host range in the myrtle family (Myrtaceae

Myrtaceae

The Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. Myrtle, clove, guava, feijoa, allspice, and eucalyptus belong here. All species are woody, with essential oils, and flower parts in multiples of four or five...

). Puccinia psidii can have very serious consequences to various species of plants in the Myrtaceae. This family includes guava

Guava

Guavas are plants in the myrtle family genus Psidium , which contains about 100 species of tropical shrubs and small trees. They are native to Mexico, Central America, and northern South America...

 (the original host of this rust in Brazil), eucalyptus

Eucalyptus

Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...

, melaleuca

Melaleuca

Melaleuca is a genus of plants in the myrtle family Myrtaceae known for its natural soothing and cleansing properties. There are well over 200 recognised species, most of which are endemic to Australia...

, and a number of species native to Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

, 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

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

, and at least one reported from California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 and there is concern that strains may exist or develop that could be devastating to ohia (Metrosideros polymorpha

Metrosideros polymorpha

The ōhia lehua is a species of flowering evergreen tree in the myrtle family, Myrtaceae, that is endemic to the six largest islands of Hawaii. It is a highly variable tree, being tall in favorable situations, and much smaller when growing in boggy soils or on basalt...

), one of Hawaii's dominant native trees, a foundation species for many remaining Hawaiian native ecosystems. However currently, the major threat of Puccinia in Hawaii is the massive damage it is doing to Eugenia koolauensis

Eugenia koolauensis

Eugenia koolauensis, commonly known as Koolau Eugenia or Nioi, is a species of flowering plant in the myrtle family, Myrtaceae. It is endemic to Hawaii, where it could previously be found on the islands of Molokai and Oahu; today populations only exist on the latter...

, a federally listed endangered species.

External links

• 2010. Loope, Lloyd L. A Summary of Information on the Rust Puccinia psidii Winter (Guava Rust) with Emphasis on Means to Prevent Introduction of Additional Strains to Hawaii. U.S. Geological Survey Open-File Report 2010-1082.
• Puccinia psidii species information from the Hawaiian Ecosystems at Risk project (HEAR)