You are here

DNA-based analyses provide critical insights into threats posed by the invasive myrtle rust pathogen

Date: April 15, 2015


Currently, an invasive myrtle rust disease pathogen is spreading around the globe, which threatens native and planted trees/shrubs in the Myrtaceae family, such as eucalypt, guava, and allspice. The established belief was that this rust disease originated on guava in Brazil, then the rust pathogen shifted its host to eucalypt after non-native eucalypts were planted in Brazil, and subsequently has shifted to other hosts around the world. DNA-based studies provided new insights into the emergent myrtle rust disease. 

Myrtle rust
Myrtle rust


Collaborative studies among the Universidade Federal de Viçosa (UFV) – Brazil, Washington State University (WSU), and USDA Forest Service –RMRS and Region 5 FHP conducted DNA analyses on myrtle rust pathogen (Puccinia psidii) samples collected from diverse tree hosts and geographic locations in Brazil.

Key Findings

  • Austropuccinia psidii infections of eucalypt did not originate via a host shift from guava
  • Austropuccinia psidii is an invasive rust pathogen that appears to comprise at least three biotypes (Pandemic, eucalypt/rose apple–Brazil/Uruguay, and guava/Brazilian guava–Brazil)
  • Each A. psidii biotype has different ecological behavior, in terms of associated hosts and suitable climate space
  • The  eucalypt/rose apple–Brazil/Uruguay t biotype of A. psidii likely poses a major threat to native ‘ōhi’a in Hawaii, and other myrtaceous hosts in Australia and Southeast Asia should this biotype ever be introduced
  • An understanding of A. psidii biotypes/genotypes is essential for tracking pathogen spread, conducting threat assessments developing regulatory measures, and implementing management strategies for this invasive pathogen


Featured Publications

Graca, Rodrigo N. ; Ross-Davis, Amy ; Klopfenstein, Ned B. ; Kim, Mee-Sook ; Peever, Tobin L. ; Cannon, Phil G. ; Aun, Cristina P. ; Mizubuti, Eduardo G. ; Alfenas, Acelino C. , 2013

National Strategic Program Areas: 
Invasive Species; Resource Management and Use
National Priority Research Areas: 
Climate Change
RMRS Science Program Areas: 
Forest and Woodland Ecosystems
RMRS Strategic Priorities: 
Disturbance Ecology; Resilient Landscapes
Principal Investigators: 
Principal Investigators - External: 
Jane E. Stewart - Colorado State University
Mee-Sook Kim - USDA Forest Service Pacific Northwest Research Station
Amy Ross-Davis - Oregon State University
Forest Service Partners: 
USDA Forest Service, State & Private Forestry, Forest Health Protection, and Region 5 (Pacific Southwest)
External Partners: 
Acelino C. Alfenas and Rodrigo N. Graça (Universidade Federal de Viçosa, Brazil)
Tobin Peever (Washington State University)
Amy Ross-Davis (RMRS collaborator)
Phil G. Cannon (USDA Forest Service-FHP, Region 5)
Patricia da S. Machado (Departamento de Fitopatologia, Universidade Federal de Vicosa, Brazil
Janice Y. Uchida (Department of Plant and Enviromental Protection Sciences, University of Hawaii at Manoa, USA)
Rob D. Hauff (Division of Forestry and Wildlife, Department of Lands and Natural Resources)
Chris Y. Kadooka (Department of Plant and Environmental Protection Sciences, University of Hawaii at Manoa, USA)
Shigetou Namba (Department of Agricultural and Environmental Biology, The University of Tokyo, Japan)
Nami Minato (Department of Agricultural and Environmental Biology, The University of Tokyo, Japan)
Sofiá Simeto (Programa Forestal, INIA Tacuarembó, Uruguay)
Carlos A. Pérez (Departamento de Protección Vegetal, Facultad de Agronomía, Universidad de la República, Uruguay)
Min B. Rayamajhi (USDA ARS – Invasive Plant Research Lab, USA)
Mauricio Morán (Desarrollos Madereros S.A., Paraguay)
D. Jean Lodge (USDA Forest Service – Northern Research Station, Puerto Rico, USA)
Marcela Arguedas (Escuela de Ingeniería Forestal, Instituto Tecnológico de Costa Rica, Costa Rica)
Rosario Medel-Ortiz (Universidad Veracruzana, Instituto de Investigaciones Forestales, Mexico)
Armando López-Ramirez (Universidad Veracruzana, Instituto de Investigaciones Forestales, Mexico)
Paula Tennant (The Biotechnology Centre, University of the West Indies, Jamaica)
Morag Glen (Tasmanian Institute of Agriculture, University of Tasmania, Australia)
Alistair R. McTaggart (University of Queensland)
Angus J. Carnegie (NSW Department of Primary Industries, NSW Forest Science, Australia)