Hawaiian Ecosystems at Risk project (HEAR)

Puccinia psidii
(Pucciniaceae)

ohia rust, eucalyptus rust, guava rust

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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. 


Featured items

A summary of information on the rust Puccinia psidii Winter (guava rust) with emphasis on means to prevent introduction of additional strains to Hawaii
Executive summary and a link to Lloyd Loope's full paper (http://pubs.usgs.gov/of/2010/1082/of2010-1082.pdf, 31 p) on guava rust is available from the USGS Pacific Island Ecosystems Research Center (2010).

Plant local for ohia View info about Adobe Acrobat PDF format
Restricting the importation to Hawaii of myrtle family plants, produce, and cut flowers is vital to protecting ohia forests, and your help is needed! This flyer presents information about how purchasing locally-grown cut flowers and foliage (especially in the family Myrtaceae) can help prevent myrtle rust from infecting one of Hawaii's dominant forest trees.

Genetic characterization of guava rust (Puccinia psidii): Evaluating pathways of spread and assessing future threats
The overall objectives of this project are to identify the origin of Puccinia psidii races that have been introduced to the USA (especially Hawaiian races), evaluate pathways of its spread, and assess future risk. We propose to 1) develop genetic markers to distinguish among existing rust races; 2) estimate the genetic diversity within Puccinia psidii populations across its native range and recent introduction areas; and 3) identify pathways of spread through genetic analyses. This information will help identify rust races that pose threats to global populations of Myrtaceae and prevent their introduction into new regions.

Puccinia psidii is the cause of rust disease of many host species in the Myrtaceae family, including guava, eucalyptus, rose apple, and ohia. First reported in 1884 on guava in Brazil, the rust has since been detected in other South America countries (Argentina, Colombia, Paraguay, Uruguay, Venezuela), Central America (Costa Rica, and Panama), the Caribbean (Cuba, Dominica, Dominican Republic, Jamaica, Puerto Rico, Trinidad and Tobago, Virgin Islands), Mexico (Gallegos and Cummins 1981), USA (Florida, California, and Hawaii), and most recently Japan.

An analysis of the risk of introduction of additional strains of the rust Puccinia psidii Winter (ohia rust) to Hawaii View info about Adobe Acrobat PDF format  important item 
This 2008 analysis of the risk of introduction of additional strains of the rust Puccinia psidii to Hawaii provided a basis for Hawaii Department of Agriculture's interim rule regulating importation of plant in the myrtle family, in place for 12 months after its enactment on August 28, 2007.


What's new?

The challenge of retarding erosion of island biodiversity through phytosanitary measures: an update on the case of Puccinia psidii in Hawaii View info about Adobe Acrobat PDF format
This 2011 report provides up-to-date information about Puccinia psidii in Hawaii and discusses the need for quarantine measures to prevent entry into Hawaii of other strains of this potentially devastating plant pathogen. Most rust fungi are highly host specific, but Puccina psidii has an extremely broad host range within Myrtaceae and gained notoriety with a host jump in its native Brazil from common guava (Psidium guajava) to commercial Eucalyptus plantations. When detected in Hawaii in April 2005, the first invasion outside the Neotropics/subtropics, there was immediate concern for ohia (Metrosideros polymorpha). Ohia comprises 80% of native forest statewide, providing stable watersheds and habitat for most Hawaiian forest birds and plants. Within months, rust spores spread statewide on wind currents, but ohia was found to be only a minor host, showing very light damage. The primary host was non-native rose apple (Syzygium jambos), severely affected at a landscape scale, but the epiphytotic subsided as rose apple was largely defoliated or killed within several years. The limited and stable host range in Hawaii (vs. elsewhere) led the local conservation community to explore possibilities for excluding new genetic strains of Puccinia psidii. Although national/international phytosanitary standards require strong scientific justification for regulations involving an infraspecific taxonomic level, hopes were buoyed when genetic studies showed no apparent genetic variation/evolution in Hawaii's rust strain. A sophisticated genetic study of Puccinia psidii in its home range is near completion; genetic variation is substantial, and host species strongly influences rust population structure. In order to prevent introduction of new strains, Hawaii Department of Agriculture is moving ahead with establishing stringent measures that restrict entry of Myrtaceae into Hawaii. Meanwhile, Puccinia psidii poses a major threat to Myrtaceae biodiversity worldwide.


Species description or overview

A summary of information on the rust Puccinia psidii Winter (guava rust) with emphasis on means to prevent introduction of additional strains to Hawaii
Executive summary and a link to Lloyd Loope's full paper (http://pubs.usgs.gov/of/2010/1082/of2010-1082.pdf, 31 p) on guava rust is available from the USGS Pacific Island Ecosystems Research Center (2010).

A summary of information on the rust Puccinia psidii Winter (guava rust) with emphasis on means to prevent introduction of additional strains to Hawaii View info about Adobe Acrobat PDF format
PDF of Lloyd Loope's full paper (http://pubs.usgs.gov/of/2010/1082/of2010-1082.pdf, 31 p) on guava rust is available from the USGS Pacific Island Ecosystems Research Center (2010).

Puccinia psidii: diagnostic fact sheet for an "invasive and emerging fungal pathogen" (USDA/ARS)
This diagnostic fact sheet from USDA/ARS* about Puccinia psidii includes information about its life history, hosts, and geographic distribution, as well as diagnostic images (including microscopic views) (*U.S. Department of Agriculture/Agricultural Research Service).

Disease index for the rust Puccinia psidii on rose apple in Hawaii View info about Adobe Acrobat PDF format  important item 
Illustrations help define the categories for this disease index and a field survey form is available for reporting Puccinia psidii rust disease (University of Hawaii).

Disease index for the rust Puccinia psidii on ohia (Metrosideros polymorpha) in Hawaii View info about Adobe Acrobat PDF format  important item 
Illustrations help define the categories for this disease index for ohia rust and a field survey form is available for reporting Puccinia psidii rust disease (University of Hawaii).

Puccinia psidii: PaDIL species content page
Images and description of host symptoms caused by Eucalyptus rust, Puccinia psidii, are on this Pest and Diseases Image Library page.


Taxonomy & nomenclature

Puccinia psidii information from ITIS
The Integrated Taxonomic Information System ITIS provides authoritative taxonomic information on Puccinia psidii, as well as other plants, animals, fungi, and microbes of North America and the world.

Uredinales species pathogenic on species of Myrtaceae
The nomenclature of the species of rust fungi that occur on species of Myrtaceae is reviewed and several changes are made. The known hosts of the myrtaceous rusts are recorded. Guava rust (aka "ohia rust"), Puccinia psidii, is now known to occur on species in both subfamilies of Myrtaceae, including one of two tribes of the subfamily Psiloxyloideae and seven of the 15 tribes of subfamily Myrtoideae, a total of 20 genera and 71 species. Susceptibility to Puccinia psidii seems to be low among species of Myrtaceae from the Americas but more common among taxa from Asia, Australia and the Pacific.

Genetic characterization of guava rust (Puccinia psidii): Evaluating pathways of spread and assessing future threats  important item 
The overall objectives of this project are to identify the origin of Puccinia psidii races that have been introduced to the USA (especially Hawaiian races), evaluate pathways of its spread, and assess future risk. We propose to 1) develop genetic markers to distinguish among existing rust races; 2) estimate the genetic diversity within Puccinia psidii populations across its native range and recent introduction areas; and 3) identify pathways of spread through genetic analyses. This information will help identify rust races that pose threats to global populations of Myrtaceae and prevent their introduction into new regions.

Puccinia psidii is the cause of rust disease of many host species in the Myrtaceae family, including guava, eucalyptus, rose apple, and ohia. First reported in 1884 on guava in Brazil, the rust has since been detected in other South America countries (Argentina, Colombia, Paraguay, Uruguay, Venezuela), Central America (Costa Rica, and Panama), the Caribbean (Cuba, Dominica, Dominican Republic, Jamaica, Puerto Rico, Trinidad and Tobago, Virgin Islands), Mexico (Gallegos and Cummins 1981), USA (Florida, California, and Hawaii), and most recently Japan.


Identification

Development of microsatellite markers for the guava rust fungus, Puccinia psidii (abstract)  important item 
Genetic markers for Puccinia psidii were developed and characterized (Molecular Ecology, 2007).

Molecular diagnosis of Puccinia psidii (guava rust)--a quarantine threat to Australian eucalypt and Myrtaceae biodiversity  important item 
An accurate and sensitive species-species specific DNA detection assay has been developed for Puccinia psidii that can serve a variety of important uses, including at-the-border quarantine protection. ("Independent testing in Brazil and Australia demonstrated the international inter-laboratory transferability of the P. psidii assay required for germplasm screening, disease monitoring and quarantine and incursion management, towards which the assay has already been employed.")

Puccinia psidii: diagnostic fact sheet for an "invasive and emerging fungal pathogen" (USDA/ARS)
This diagnostic fact sheet from USDA/ARS* about Puccinia psidii includes information about its life history, hosts, and geographic distribution, as well as diagnostic images (including microscopic views) (*U.S. Department of Agriculture/Agricultural Research Service).

Uredinales species pathogenic on species of Myrtaceae
The nomenclature of the species of rust fungi that occur on species of Myrtaceae is reviewed and several changes are made. The known hosts of the myrtaceous rusts are recorded. Guava rust (aka "ohia rust"), Puccinia psidii, is now known to occur on species in both subfamilies of Myrtaceae, including one of two tribes of the subfamily Psiloxyloideae and seven of the 15 tribes of subfamily Myrtoideae, a total of 20 genera and 71 species. Susceptibility to Puccinia psidii seems to be low among species of Myrtaceae from the Americas but more common among taxa from Asia, Australia and the Pacific.

Disease index for the rust Puccinia psidii on ohia (Metrosideros polymorpha) in Hawaii View info about Adobe Acrobat PDF format
Illustrations help define the categories for this disease index for ohia rust and a field survey form is available for reporting Puccinia psidii rust disease (University of Hawaii).

Disease index for the rust Puccinia psidii on rose apple in Hawaii View info about Adobe Acrobat PDF format  important item 
Illustrations help define the categories for this disease index and a field survey form is available for reporting Puccinia psidii rust disease (University of Hawaii).

Uredinales species pathogenic on species of Myrtaceae
Simpson, J.A., K. Thomas, and C.A. Grgurinovic. 2006. Uredinales species pathogenic on species of Myrtaceae. Australasian Plant Pathology 35(5) 549-562.


Pest alerts

Ohia rust pest advisory (HDOA) View info about Adobe Acrobat PDF format
A "new pest advisory" RE: ohia rust (Puccinia psidii), a rust which which affects the native Hawaiian forest tree ohia (Metrosideros polymorpha) and many other species in the myrtle family (Myrtaceae), was issued by the Hawaii Department of Agriculture. This rust has wide host range including eucalyptus, paperbark tree, guava, rose apple, allspice, jaboticaba, Surinam cherry, species of Eugenia, and others in the family Myrtaceae. In other parts of the world, the rust is referred to as eucalyptus rust or guava rust.

Hawaii restrictions on importation of all Myrtaceae plants View info about Adobe Acrobat PDF format  important item 
Ohia rust regulations in Hawaii resulted in this phytosanitary advisory from the State of California Department of Food and Agriculture (19 November 2007).

A new rust occurring on ohia, Metrosideros polymorpha
A rust--tentatively identified as Puccinia psidii--has been found on nursery seedlings of ohia (Metrosideros polymorpha). This could be a new disease to Hawaii's most common forest tree. CTAHR has issued this pest alert in response to a rust occurring on the Hawaiian native tree Metrosideros polymorpha and other species.

Pacific Island Network--Featured Concern: Ohia Rust View info about Adobe Acrobat PDF format
An overview of Puccinia psidii, its introduction to the Pacific islands, and information on management techniques are provided in this printable NPS information sheet.


Impacts

2005 Annual Report for Hawaii Department of Agriculture (HDOA) View info about Adobe Acrobat PDF format
Projects involving invasive species are reviewed in the 2005 HDOA annual report.

Puccinia psidii images
Images of Puccinia psidii rust on ohia are from The Plant Doctor, a University of Hawaii service that provides information and online diagnosis for plant pathogens and diseases in Hawaii and the tropics.

Rust ruins rose apple; guardians fear for ohia  important item 
The importance of the threat of the so-called "ohia rust" to the future of Hawaii's native forest is highlighted in this December 2008 Maui News article written by Dr. Lloyd Loope for the Maui Invasive Species Committee's series "Kiai Moku" ("guarding the island").

Puccinia psidii: a threat to the Australian environment and economy: a review
Glen et al. (2007) provide an updated summary of Puccinia psidii distribution.


Hosts

Uredinales species pathogenic on a species of Myrtaceae  important item 
A recent (2006) synopsis of worldwide hosts of Puccinia psidii is presented here. Puccinia psidii is now known to occur on species in both subfamilies of Myrtaceae, including one of two tribes of the subfamily Psiloxyloideae and seven of the 15 tribes of subfamily Myrtoideae, a total of 20 genera and 71 species. Susceptibility to Puccinia psidii seems to be low among species of Myrtaceae from the Americas but more common among taxa from Asia, Australia and the Pacific.

Host range of Puccinia psidii, a potential biological control agent of Melaleuca quinquenervia in Florida View info about Adobe Acrobat PDF format
Puccinia psidii caused disease symptoms on M. quinquenervia, including distortion and abscission of young foliage and dieback of severely infected tips (Rayachhetry, M. B., T.K., Van, T.D. Center, and M. Elliott. 2001. Host range of Puccinia psidii, a potential biological control agent of Melaleuca quinquenervia in Florida. Biological Control 22:38-45.) (NOTE: Puccinia psidii would never be considered for importation as a biological control agent, given its reputation for broad host range within the Myrtaceae; it reached Florida in the late 1970s, but was not introduced as a biocontrol agent.)

Fungus/host database records for Puccinia psidii
Citation records of fungus-host interactions for Puccinia psidii are compiled by the USDA Agriculture Research Service's Systematic Mycology and Microbiology Laboratory Fungus-Host Distributions Database.

First report of rust caused by Puccinia psidii on paperbark, Melaleuca quinquenervia, in California
Infections by Puccinia psidii were detected on Melaleuca quinquenervia (paperbark, tea tree) during a regular inspection of a San Diego, California nursery in November, 2010 by San Diego County inspectors.

Ohia: backbone of Hawaii's terrestrial ecosystems and culture View info about Adobe Acrobat PDF format
A poster about the importance of ohia (Metrosideros polymorpha) in Hawaii's native forest was presented at at International Union of Forestry Research Organizations' Conference on Invasive Species in International Trade in May, 2008. (PDF size: 425Kb) (Also available as a tabloid-sized PDF [PDF size: 620Kb].) (Citation: Buermeyer, K., L. Loope, A.M. La Rosa, and R. Hauff. 2008. Ohia: backbone of Hawaii's terrestrial ecosystems and culture. Poster presentation at International Union of Forestry Research Organizations' Conference on Invasive Species in International Trade, Shepherdstown, West Virginia, USA, May 27-30, 2008.)

[RE: CQR=5 : see "HEARWEB record comments"] A database of worldwide hosts of Puccinia rust, including new records from Hawaii
[RE: CQR=5 : see "HEARWEB record comments"] A database of worldwide hosts of Puccinia rust, including new records from Hawaii (November 2006), by Rob Anderson of the USGS-BRD-PIERC, is available online as an MS-Excel spreadsheet.


Dispersal and pathways

Genetic characterization of guava rust (Puccinia psidii): Evaluating pathways of spread and assessing future threats  important item 
The overall objectives of this project are to identify the origin of Puccinia psidii races that have been introduced to the USA (especially Hawaiian races), evaluate pathways of its spread, and assess future risk. We propose to 1) develop genetic markers to distinguish among existing rust races; 2) estimate the genetic diversity within Puccinia psidii populations across its native range and recent introduction areas; and 3) identify pathways of spread through genetic analyses. This information will help identify rust races that pose threats to global populations of Myrtaceae and prevent their introduction into new regions.

Puccinia psidii is the cause of rust disease of many host species in the Myrtaceae family, including guava, eucalyptus, rose apple, and ohia. First reported in 1884 on guava in Brazil, the rust has since been detected in other South America countries (Argentina, Colombia, Paraguay, Uruguay, Venezuela), Central America (Costa Rica, and Panama), the Caribbean (Cuba, Dominica, Dominican Republic, Jamaica, Puerto Rico, Trinidad and Tobago, Virgin Islands), Mexico (Gallegos and Cummins 1981), USA (Florida, California, and Hawaii), and most recently Japan.

Rust ruins rose apple; guardians fear for ohia  important item 
The importance of the threat of the so-called "ohia rust" to the future of Hawaii's native forest is highlighted in this December 2008 Maui News article written by Dr. Lloyd Loope for the Maui Invasive Species Committee's series "Kiai Moku" ("guarding the island").


Risk assessments

An analysis of the risk of introduction of additional strains of the rust Puccinia psidii Winter (ohia rust) to Hawaii View info about Adobe Acrobat PDF format  important item 
This 2008 analysis of the risk of introduction of additional strains of the rust Puccinia psidii to Hawaii provided a basis for Hawaii Department of Agriculture's interim rule regulating importation of plant in the myrtle family, in place for 12 months after its enactment on August 28, 2007.

[replaced by http://www.hear.org/species/puccinia_psidii/pdfs/ofr_2008_1008_loope_ohia_rust_assessment.pdf]
Risk assessment for Hawaii for new strains of the rust Puccinia psidii


Prevention

Plant local for ohia View info about Adobe Acrobat PDF format
Restricting the importation to Hawaii of myrtle family plants, produce, and cut flowers is vital to protecting ohia forests, and your help is needed! This flyer presents information about how purchasing locally-grown cut flowers and foliage (especially in the family Myrtaceae) can help prevent myrtle rust from infecting one of Hawaii's dominant forest trees.

Molecular diagnosis of Puccinia psidii (guava rust)--a quarantine threat to Australian eucalypt and Myrtaceae biodiversity  important item 
An accurate and sensitive species-species specific DNA detection assay has been developed for Puccinia psidii that can serve a variety of important uses, including at-the-border quarantine protection. ("Independent testing in Brazil and Australia demonstrated the international inter-laboratory transferability of the P. psidii assay required for germplasm screening, disease monitoring and quarantine and incursion management, towards which the assay has already been employed.")

Hawaii Board of Agriculture actions for the 28 August 2007 meeting  important item 
Requests for quarantine measures to control varroa mite and ohia rusts are approved.

Assessment of eucalypt rust as a pathogen of Eucalyptus spp. and other Myrtaceae, and development of sensitive methods for its detection in germplasm in Australia View info about Adobe Acrobat PDF format
The susceptibility of species to Puccinia psidii was investigated, a DNA-based 'fingerprint' was developed for the unequivocal identification of P. psidii, and through bioclimatic modelling, regions were identified where the rust could be expected to cause severe epidemics in native vegetation and plantations. This research report was prepared by ACIAR, Australia (2007).

Hawaii Board of Agriculture meeting actions 8/28/2007
A prohibition on the importation of plants and plant parts in the family Myrtaceae from areas infested by Puccinia psidii was enacted by the Hawaii DOA.


Control methods

Control of rust (Puccinia psidii) in guava (Psidium guajava)
"The guava rust, caused by Puccinia psidii Wint., attacks all the young tissues of the plant and can cause losses up to 80 to 100%. With the objective of verifying the efficiency of some fungicides on such disease, an experiment was conducted in the agricultural year 1994/1995, in Louveira, State of Sao Paulo...." (from the document's abstract).

Breeding guava for resistance to rust caused by Puccinia psidii in Brazil View info about Adobe Acrobat PDF format
Individual guava plants not affected by Puccinia psidii rust were selected for use in a breeding program to develop rust-resistant varieties (Canadian Society for Horticultural Science symposium abstract, 2002).

Hawaii Board of Agriculture meeting actions 8/28/2007
A prohibition on the importation of plants and plant parts in the family Myrtaceae from areas infested by Puccinia psidii was enacted by the Hawaii DOA.

Puccinia psidii: a threat to the Australian environment and economy: a review
Glen et al. (2007) provide an updated summary of Puccinia psidii distribution.


Legislation/regulation

Hawaii Board of Agriculture actions for the 28 August 2007 meeting  important item 
Requests for quarantine measures to control varroa mite and ohia rusts are approved.

Hawaii restrictions on importation of all Myrtaceae plants View info about Adobe Acrobat PDF format  important item 
Ohia rust regulations in Hawaii resulted in this phytosanitary advisory from the State of California Department of Food and Agriculture (19 November 2007).

HDOA restrictions on the importation into Hawaii of plants and plant parts in the family Myrtaceae View info about Adobe Acrobat PDF format  important item 
"Restrictions on the importation into Hawaii of plants and plant parts in the family Myrtaceae" (Hawaii State Department of Agriculture Plant Quarantine Interim Rule 07-2) was implemented for one year beginning 28 August 2007.

Ohia rust threat is as large as ever, but ban on imports is allowed to lapse View info about Adobe Acrobat PDF format  important item 
In 2007, in response to the alarm raised by natural resource managers, the Hawaii State Department of Agriculture adopted an emergency rule banning the import of Myrtaceae plants and plant parts from the states of California and Florida and from Central and South America. When the rule expired in late August 2008, the DOA was still working on a permanent rule.

Eucalyptus rust caused by Puccinia psidii and the threat it poses to Australia
"Puccinia psidii, which causes the disease Eucalyptus rust, poses a threat to biodiversity in Australia and the Eucalyptus forest industry worldwide. It is native to South America and Central America and has spread to North America (Mexico, USA - Florida). In mid-2005, the rust was reported in Hawaii, USA, which means it is now present in the Pacific region."


Images

Images of Puccinia psidii ("ohia rust")
Images of Puccinia psidii ("ohia rust") are provided by Forest & Kim Starr.

Puccinia psidii: diagnostic fact sheet for an "invasive and emerging fungal pathogen" (USDA/ARS)
This diagnostic fact sheet from USDA/ARS* about Puccinia psidii includes information about its life history, hosts, and geographic distribution, as well as diagnostic images (including microscopic views) (*U.S. Department of Agriculture/Agricultural Research Service).

Rose apple (Syzigium jambos) on Maui infected with the rust Puccinia psidii
Images of rose apple (Syzigium jambos) on Maui infected with the rust Puccinia psidii are presented online by Maui photographer Philip Thomas, and are freely available for noncommercial use.

Puccinia psidii images from Wikimedia Commons
Images of ohia rust on rose apple are posted on Wikimedia. All images on Wikimedia are free for public use [http://wikimediafoundation.org/wiki/Terms_of_Use].

Puccinia psidii images
Images of Puccinia psidii rust on ohia are from The Plant Doctor, a University of Hawaii service that provides information and online diagnosis for plant pathogens and diseases in Hawaii and the tropics.

Disease index for the rust Puccinia psidii on rose apple in Hawaii View info about Adobe Acrobat PDF format  important item 
Illustrations help define the categories for this disease index and a field survey form is available for reporting Puccinia psidii rust disease (University of Hawaii).

Disease index for the rust Puccinia psidii on ohia (Metrosideros polymorpha) in Hawaii View info about Adobe Acrobat PDF format  important item 
Illustrations help define the categories for this disease index for ohia rust and a field survey form is available for reporting Puccinia psidii rust disease (University of Hawaii).

AQIS field guide to exotic pests and diseases: eucalyptus rust
Eucalyptus rust images and brief overview are provided by Australian Quarantine and Inspection Service's field guide to exotic pests and diseases.

Puccinia psidii images
Plant symptoms and micrographs of Puccinia psidii are on the Forestry Images site.

Puccinia psidii: PaDIL species content page
Images and description of host symptoms caused by Eucalyptus rust, Puccinia psidii, are on this Pest and Diseases Image Library page.

"Ohia rust" (Puccinia psidii) on ohia (Metrosideros polymorpha)
Images of "ohia rust" (Puccinia psidii) on ohia (Metrosideros polymorpha) are provided by "The Plant Doctor" (Scot Nelson).


Distribution

Puccinia psidii on Eucalyptus globulus in Uruguay
"Puccinia psidii is native to South and Central America and the Caribbean, where it causes a serious leaf and shoot disease of a wide range of Myrtaceae (Coutinho et al., 1998). These include the native Psidium guajava (guava) and introduced Eucalyptus species (Ferreira, 1983). In 2002 a rust fungus was observed causing severe damage to one-year old trees during a routine disease survey of E. globulus in Uruguay...."

First report of rust disease on ohia and the causal fungus, Puccinia psidii, in Japan (citation and abstract)
The rust disease on ohia and the occurrence of its causal fungus, Puccinia psidii, were discovered in Japan in 2007 in (Journal of General Plant Pathology, 2009).

Puccinia psidii: a threat to the Australian environment and economy: a review  important item 
Glen et al. (2007) provide an updated summary of Puccinia psidii distribution.


Case studies

Emerging diseases - Ready and waiting?
Eucalyptus rust (Puccinia psidii) is a serious threat to an Australian national icon (Eucalyptus). In Australia, Puccinia psidii--a 'new encounter' disease--"must be regarded as one of the most serious quarantine threats to Australia."


In the news

The towering risk of making this place like every other place
Journalist Jan Tenbruggencate writes of the threat of a rust (Puccinia psidii) that may have the potential to have serious impact on Hawaii's native forests.

Rust ruins rose apple; guardians fear for ohia View info about Adobe Acrobat PDF format
USGS scientist Lloyd Loope discusses the potential impacts of the pathogen Puccinia psidii on Hawaii's native forests. He says: "Enforcement of stringent Hawaii quarantine regulations would seem to provide the only effective means of protecting our ohia forest. If we lose ohia, we lose our forest."

Rust ruins rose apple; guardians fear for ohia  important item 
The importance of the threat of the so-called "ohia rust" to the future of Hawaii's native forest is highlighted in this December 2008 Maui News article written by Dr. Lloyd Loope for the Maui Invasive Species Committee's series "Kiai Moku" ("guarding the island").

Trees dying off
"Forestry experts fear that a virulent fungus killing rose apple trees on Oahu may spread to ohia trees and other vulnerable native p lants."

Trees dying off (Star Bulletin 8/24/2008)
A virulent fungus killing rose apple trees on Oahu may spread to ohia trees and other vulnerable native plants.

Import ban to affect shipments to Hawaii florists
To prevent imports of the ohia diease Puccinia psidii, the Hawaii Department of Agriculture has banned plants from the Myrtaceae family from California, Florida and South America that could be disease hosts (Honolulu Advertiser, 9/6/2007).


Full-text articles

The challenge of retarding erosion of island biodiversity through phytosanitary measures: an update on the case of Puccinia psidii in Hawaii View info about Adobe Acrobat PDF format
This 2011 report provides up-to-date information about Puccinia psidii in Hawaii and discusses the need for quarantine measures to prevent entry into Hawaii of other strains of this potentially devastating plant pathogen. Most rust fungi are highly host specific, but Puccina psidii has an extremely broad host range within Myrtaceae and gained notoriety with a host jump in its native Brazil from common guava (Psidium guajava) to commercial Eucalyptus plantations. When detected in Hawaii in April 2005, the first invasion outside the Neotropics/subtropics, there was immediate concern for ohia (Metrosideros polymorpha). Ohia comprises 80% of native forest statewide, providing stable watersheds and habitat for most Hawaiian forest birds and plants. Within months, rust spores spread statewide on wind currents, but ohia was found to be only a minor host, showing very light damage. The primary host was non-native rose apple (Syzygium jambos), severely affected at a landscape scale, but the epiphytotic subsided as rose apple was largely defoliated or killed within several years. The limited and stable host range in Hawaii (vs. elsewhere) led the local conservation community to explore possibilities for excluding new genetic strains of Puccinia psidii. Although national/international phytosanitary standards require strong scientific justification for regulations involving an infraspecific taxonomic level, hopes were buoyed when genetic studies showed no apparent genetic variation/evolution in Hawaii's rust strain. A sophisticated genetic study of Puccinia psidii in its home range is near completion; genetic variation is substantial, and host species strongly influences rust population structure. In order to prevent introduction of new strains, Hawaii Department of Agriculture is moving ahead with establishing stringent measures that restrict entry of Myrtaceae into Hawaii. Meanwhile, Puccinia psidii poses a major threat to Myrtaceae biodiversity worldwide.

A summary of information on the rust Puccinia psidii Winter (guava rust) with emphasis on means to prevent introduction of additional strains to Hawaii
Executive summary and a link to Lloyd Loope's full paper (http://pubs.usgs.gov/of/2010/1082/of2010-1082.pdf, 31 p) on guava rust is available from the USGS Pacific Island Ecosystems Research Center (2010).

A summary of information on the rust Puccinia psidii Winter (guava rust) with emphasis on means to prevent introduction of additional strains to Hawaii View info about Adobe Acrobat PDF format
PDF of Lloyd Loope's full paper (http://pubs.usgs.gov/of/2010/1082/of2010-1082.pdf, 31 p) on guava rust is available from the USGS Pacific Island Ecosystems Research Center (2010).

Incidence and evaluation of a new rust disease on Myrtaceae in Hawaii: Puccinia psidii Winter, guava rust View info about Adobe Acrobat PDF format
The newly-discovered (2005) "presence [of guava rust, Puccinia psidii] in Hawaii is particularly troubling because ohia-lehua [a tree closely related to this rust's hosts] is the dominant overstory tree in over 80% of Hawaii's native forests and is present over a broad environmental gradient in early to late successional stages. Native plant community function, particularly reproductive capacity, could be seriously affected by the spread of the rust." This poster was created by Ann Marie LaRosa (USDA/Forest Service) and Rob Hauff (State of Hawaii DLNR/DOFAW). (Note: editorial notes in brackets--[]--were added by the HEAR webmaster.)

Host range of Puccinia psidii, a potential biological control agent of Melaleuca quinquenervia in Florida View info about Adobe Acrobat PDF format
Puccinia psidii caused disease symptoms on M. quinquenervia, including distortion and abscission of young foliage and dieback of severely infected tips (Rayachhetry, M. B., T.K., Van, T.D. Center, and M. Elliott. 2001. Host range of Puccinia psidii, a potential biological control agent of Melaleuca quinquenervia in Florida. Biological Control 22:38-45.) (NOTE: Puccinia psidii would never be considered for importation as a biological control agent, given its reputation for broad host range within the Myrtaceae; it reached Florida in the late 1970s, but was not introduced as a biocontrol agent.)

Puccinia psidii attacks melaleuca View info about Adobe Acrobat PDF format
Biocontrol of invasive melaleuca with the rust Puccinia psidii may be considered after researchers discover a natural epiphytotic in Florida (Plant Disease, 1997).

Herbário Uredinológico "Victória Rossetti"
Images of Puccinia psidii spores accompany this article from Brazil (in Portugese).

Molecular diagnosis of Puccinia psidii (guava rust) - a quarantine threat to Australian eucalypt and Myrtaceae biodiversity
A species-specific detection assay for guava rust was developed for germplasm screening, disease monitoring and quarantine and incursion management (abstract, Plant Pathology, 2008).

First report of rust disease on ohia and the causal fungus, Puccinia psidii, in Japan (citation and abstract)
The rust disease on ohia and the occurrence of its causal fungus, Puccinia psidii, were discovered in Japan in 2007 in (Journal of General Plant Pathology, 2009).

Puccinia psidii: a threat to the Australian environment and economy--a review
Puccinia psidii causes a rust disease on a broad range of hosts in the Myrtaceae and Heteropyxidaceae. It is native to South America where it can cause severe disease in eucalypt plantations and other introduced Myrtaceae. The pathogen has recently expanded its geographical range to Hawaii, increasing concerns about the potential for an incursion in Australia. This paper reviews the taxonomy, biology, impact and options for control of P. psidii. It also discusses the probable impact if an incursion were to occur in Australia and the preparations that must be made to mitigate adverse consequences.

First report of rust caused by Puccinia psidii on paperbark, Melaleuca quinquenervia, in California
Infections by Puccinia psidii were detected on Melaleuca quinquenervia (paperbark, tea tree) during a regular inspection of a San Diego, California nursery in November, 2010 by San Diego County inspectors.

Disease index for the rust Puccinia psidii on ohia (Metrosideros polymorpha) in Hawaii
Uchida, Janice Y., Robert C. Anderson, Chris Y. Kadooka, Anne Marie LaRosa, and Cheresa Coles. 2008. Disease index for the rust Puccinia psidii on ohia (Metrosideros polymorpha) in Hawaii. CTAHR Plant Disease publication PD-38, Feb. 2008. College of Tropical Agriculture and Human Resources (CTAHR). Honolulu. 16 pp. illus.

Disease index for the rust Puccinia psidii on rose apple in Hawaii
Anderson, Robert C. and Janet Y. Uchida. 2008. Disease index for the rust Puccinia psidii on rose apple in Hawaii. CTAHR Plant Disease publication PD-38, Feb. 2008. College of Tropical Agriculture and Human Resources (CTAHR). Honolulu. 12 pp. illus.

Uredinales species pathogenic on species of Myrtaceae
Simpson, J.A., K. Thomas, and C.A. Grgurinovic. 2006. Uredinales species pathogenic on species of Myrtaceae. Australasian Plant Pathology 35(5) 549-562.

Eucalyptus rust: A disease with the potential for serious international implications.
Coutinho, T.A., M.J. Wingfield, A.C. Alfenas, and P.W. Crous. 1998. Eucalyptus rust: A disease with the potential for serious international implications. Plant Dis. 82:819-825.

Uredinales species pathogenic on a species of Myrtaceae
A recent (2006) synopsis of worldwide hosts of Puccinia psidii is presented here. Puccinia psidii is now known to occur on species in both subfamilies of Myrtaceae, including one of two tribes of the subfamily Psiloxyloideae and seven of the 15 tribes of subfamily Myrtoideae, a total of 20 genera and 71 species. Susceptibility to Puccinia psidii seems to be low among species of Myrtaceae from the Americas but more common among taxa from Asia, Australia and the Pacific.

Puccinia psidii: a threat to the Australian environment and economy--a review
Puccinia psidii causes a rust disease on a broad range of hosts in the Myrtaceae and Heteropyxidaceae. It is native to South America where it can cause severe disease in eucalypt plantations and other introduced Myrtaceae. The pathogen has recently expanded its geographical range to Hawaii, increasing concerns about the potential for an incursion in Australia. This paper reviews the taxonomy, biology, impact and options for control of P. psidii. It also discusses the probable impact if an incursion were to occur in Australia and the preparations that must be made to mitigate adverse consequences. (=abstract)

Resistance to rust (Puccinia psidii) in eucalyptus: mode of inheritance and mapping of a major gene with RAPD markers (abstract)
The resistance to rust is genetically controlled in eucalyptus and is one of the few examples of the involvement of a major gene in a non-coevolved pathosystem (Theoretical and Applied Genetics, 2003).


Abstracts

Molecular diagnosis of Puccinia psidii (guava rust) - a quarantine threat to Australian eucalypt and Myrtaceae biodiversity
A species-specific detection assay for guava rust was developed for germplasm screening, disease monitoring and quarantine and incursion management (abstract, Plant Pathology, 2008).


Presentations

Developing an Australian guava rust strategy View info about Adobe Acrobat PDF format
Guava rust's significant threat to Myrtaceae and biodiversity in Australia, the Pacific and South-East Asia, is examined by the Australian Center for Agricultural Research (2/10/2006).


Other resources

Uredinales species pathogenic on species of Myrtaceae
The nomenclature of the species of rust fungi that occur on species of Myrtaceae is reviewed and several changes are made. The known hosts of the myrtaceous rusts are recorded. Guava rust (aka "ohia rust"), Puccinia psidii, is now known to occur on species in both subfamilies of Myrtaceae, including one of two tribes of the subfamily Psiloxyloideae and seven of the 15 tribes of subfamily Myrtoideae, a total of 20 genera and 71 species. Susceptibility to Puccinia psidii seems to be low among species of Myrtaceae from the Americas but more common among taxa from Asia, Australia and the Pacific.

Interactive association between Puccinia psidii and Oxyops vitiosa, two introduced natural enemies of Melaleuca quinquenervia in Florida (abstract)
Puccina psidii and Oxyops vitiosa influence each other's life cycle and possibly antagonize each other's effects as biological control agents of M. quinquenervia because both agents compete for newly expanding foliar tissues for colonization, reproduction, and survival during their early stages of development.

Puccinia psidii attacks melaleuca View info about Adobe Acrobat PDF format
Biocontrol of invasive melaleuca with the rust Puccinia psidii may be considered after researchers discover a natural epiphytotic in Florida (Plant Disease, 1997).

Guava Rust by any other name, may just be as bad: Australia needs to do more now
Guava rust complex background and recommended actions are from the Australasian Plant Pathology Society, Inc.

Ecological studies of Puccinia psidii (in Portugese) View info about Adobe Acrobat PDF format
Temperature effects on the germination of Puccinia psidii spores are part of this summary of a thesis from Universidade Estadual Paulista, Sao Paulo (6/21/2001).

Puccinia psidii on Eucalyptus globulus in Uruguay
"Puccinia psidii is native to South and Central America and the Caribbean, where it causes a serious leaf and shoot disease of a wide range of Myrtaceae (Coutinho et al., 1998). These include the native Psidium guajava (guava) and introduced Eucalyptus species (Ferreira, 1983). In 2002 a rust fungus was observed causing severe damage to one-year old trees during a routine disease survey of E. globulus in Uruguay...."

Heteropyxis natalensis, a new host of Puccinia psidii rust (abstract)
The first species outside the Myrtaceae shown to be susceptible to P. psidii is a South African tree (Australasian Plant Pathology, 2005).

CTAHR eXchange information on Puccinia psidii presentations
Presentations on guava rust were made by University of Hawaii faculty at the 2008 Hawaii Conservation Conference, according to this posting on the College of Tropical Agriculture and Human Resources electronic bulletin board.

CTAHR Research News, September 2006 (vol. 2, issue 7) View info about Adobe Acrobat PDF format
Citation for "First report of a rust disease on Ohia caused by Puccinia psidii in Hawaii" is listed on the last page of this newsletter.

Ohia rust information from CTAHR Hawaii Forestry Extension
Links to good information about ohia rust (Puccinia psidii) and its hosts are presented by the Hawaii Forestry Extension (CTAHR/University of Hawaii).

Eucalyptus rust contingency plan developed
Australian plant health authorities are better prepared for an incursion of eucalyptus rust (also known as guava rust) with the completion of a contingency plan for the disease (article in Plant Protection News, 3/2008).

AQIS field guide to exotic pests and diseases: eucalyptus rust
Eucalyptus rust images and brief overview are provided by Australian Quarantine and Inspection Service's field guide to exotic pests and diseases.

Review of "Diseases and Pathogens of Eucalypts" View info about Adobe Acrobat PDF format
"Highly commended as a reference text to practising forest pathologists, eucalypt foresters, researchers, university teachers and students at tertiary level", is the conclusion of this review of the book on eucalypt diseases published by CSIRO, Australia, 2000.

Hawaii Board of Agriculture meeting actions 8/28/2007
A prohibition on the importation of plants and plant parts in the family Myrtaceae from areas infested by Puccinia psidii was enacted by the Hawaii DOA.

Puccinia psidii information from CTAHR (Univ. Hawaii)
A rust (ed.: subsequently identified as Puccinia psidii) was reported found on nursery seedlings of ohia (Metrosideros polymorpha), one of Hawaii's most common forest trees.

Interaction between fungal rust Puccinia psidii and Australian weevil Oxyops vitiosa, on Melaleuca quinquenervia in Florida View info about Adobe Acrobat PDF format
Rust fungus and Australian weevil, two naturalized enemies of melaleuca, compete for newly expanding foliar tissue and may antagonize each other's effects as biocontrol agents of melaleuca (Rayamajhi, M.B., T.K. Van, P.D. Pratt, and T.D. Center. 2006. Interactive association between Puccinia psidii and Oxyops vitiosa, two introduced natural enemies of Melaleuca quinquenervia in Florida. Biological Control. 37:56-67.)


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