EXPERIMENTS AND EXPERIENCES TO BETTER UNDERSTAND THE PATHOGENIC POTENTIAL OF AUSTROPUCCINIA PSIDII 1)The impact of different strains of Austropuccinia psidii on Hawaii s ohia (Metrosideros polymorpha); 2) The impact of tree genotype and weather on disease expression. By: Phil Cannon U.S.D.A. Forest Service Presented to the Myrtle Rust Symposium Auckland, NZ August 28, 2017
The impact of different strains of Puccinia psidii on Hawaii s ohia Roccabado et al., 2003
Janice Uchida and Eloise Kilgore Find the rust, Puccinia psidii, in 2004
Massive Rose Apple Dieback
In Hawaii, the biggest concerns are for the extensive ohia (Metrosideros polymorpha) forests
Prof. Acelino Alfenas
Puccinia psidii on Guava 1884 G. Winters Photos: Alfenas et al, 2009
In 1973, Puccinia psidii shows up on Eucalyptus grandis and Brazil gets really interested.
Eucalypts are a big business in Brazil
Rodrigo s Sandwich Program
Sampling for Puccinia psidii in Brazil
NJ Tree (using 6 loci) showing the relationship among P. psidii isolates
Host species and locations in Brazil from which each of the five Puccinia psidii strains were isolated. Strain Host Species From Location of Elevation Number Which Isolated Host masl 1 Eucalyptus grandis Sao Paulo 550 2 urophylla x grandis Bahia 78 3 Myrciaria cauliflora Minas Gerais 675 4 Psidium guajava Minas Gerais 587 5 Psidium araca Bahia 120
The six ohia (Metrosideros polymorpha) seed sources used in this test. Family Variety of M. Location Elevation Number polymorpha 1 incana Kapoho Town 25 5 glaberrima Volcano Road 1177 7 glaberrima Saddle Road 1293 8 glaberrima Saddle Road 1284 11 polymorpha Saddle Road 1452 12 polymorpha Saddle Road 1232
Inoculation technique: A measured dosage of uridiniospores from a specific genotype of Puccinia psidii is applied to the underside of leaves of each plant in this splitplot. Immediately after inoculation, this set of ohia seedlings was put in a humid, warm, darkened chamber for 12 hours to promote spore gemination and infection.
Different Strains Cause Different Levels of Infection
Photo of an ohia leaf infected by Puccinia psidii and the image of this same leaf after transformation by the QUANT Image Processing Software (Vale et al. 2003). In this example, 26.65% of the area of the leaf was colonized and this was recorded as the disease severity for this leaf.
Mean percentage of leaf coverage by uredinia following inoculation with five different Puccinia psidii strains on six different ohia (Metrosideros polymorpha) families at 20 days post-inoculation. Strain Host Species From Percent of leaf covered Number Which Isolated by uredinia 1 Eucalyptus grandis 18.1a 2 urophylla x grandis 14.4a 3 Myrciaria cauliflora 15.3a 4 Psidium guajava 4.1b 5 Psidium araca 3.0b
Family Variation in Susceptibility 18 16 14 12 10 8 6 4 2 0 Damage % Ohia 1 Ohia 5 Ohia 7 Ohia 8 Ohia 11 Ohia 12 Damage %
Impact of Puccinia psidii on growth and survival of ohia. Not inoculated Inoculated AUPGC Biomass 549 174 Survival 58.3% 31.3% Not inoculated Inoculated
Conclusions of this study relevant to Hawaii T H E R E A R E M A N Y O T H E R S T R A I N S O F P U C C I N I A P S I D I I ( T H E R U S T ) T H A T A R E C U R R E N T L Y O U T S I D E O F H A W A I I. S O M E O F T H E S E S T R A I N S A R E H I G H L Y P A T H O G E N I C O N O H I A, S O M E O F T H E S E A R E N O T. H O W H A W A I I A N S U S E T H I S I N F O R M A T I O N I S U P T O H A W A I I A N S!
Protecting Hawaii by preventing further strains from entering state P. psidii is federally actionable for Hawaii-bound imports (relies on visual detection of disease symptoms) A Hawaii Department of Agriculture rule requiring quarantine for all live plant material of Myrtaceae species is currently under review by the state attorney general APHIS is considering using the Not Authorized Pending Pest Risk Analysis (NAPPRA) rule in combination with a federal order to restrict Myrtaceae plant material entering Hawaii 2014 Hawaii State Legislature passed a resolution urging state and federal quarantine agencies to use their authorities to prevent additional strains from entering the state State and federal agencies are coordinating so restrictions can be introduced simultaneously Synopsis courtesy of Rob Hauff of DOFAW
36 out of the 80 Hawaiian Myrtaceae species are susceptible to Puccinia psidii Genus # of Species Calistemon 2 Eucalyptus 6 Eugenia 4 Metrosideros 4 Pimenta 2 Syzygium 10
Contributors Brazil ( all of UF Vicosa) Acelino Couto Alfenas Rodrigo Graca Neves Andre Costa da Silva Cristina Aun Pedro Andrade Mainland US Ned Klopfenstein RMRS Amy Ross-Davis RMRS John Hanna RMRS Tobin Peever WSU Phil Cannon USDA For. Serv. Hawaii Janice Uchida U of H Eloise Kilgore Rob Hauff DOFAW Aileen Yeh HARC Chris Kadooka U of H Lloyd Loope USGS J.B. Friday U of H Rob Anderson U of H Shaobin Zhong U of H Anne-Marie LaRosa USFS Cherisa Cole U of H
Known Distribution of Puccinia psidii Identified using molecular techniques Not yet found, but where Myrtaceae are native or planted abundantly
Phylogenetic tree for some genera in the Myrtaceae 4,600 species worldwide! Over 80 of these are in Hawaii
Note: from Alvares et al, 2016
From UBC Botany (& Google)
Selecting for Resistance among Eucalyptus grandis genotypes in Sao Paulo, Brazil (from Silva et al, 2013)
Poamoho Rust Site N
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Kahana Rust Site Trade Winds Poamoho Rust Site N
Environment (E) The Infamous Disease Triangle Imagine that disease propensity is proportional to the size of the triangle
H E New Pathogen
H Conducive Environment New Pathogen
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