CANADIAN FOOD INSPECTION AGENCY  
59 Camelot Drive  
Ottawa, Ontario  
K1A OY9  
Tel: 613 -225-2342    FAX: 613 -773-7163  RMD -13-08 (Consultation)  
Date  
January 23, 201 4 
 
Title:  Pest Risk Management Document – Hymenoscyphus pseudo albidus   (ash dieback  
pathogen ) 
 
 
 
 
 
Preface  
 
As described by the International Plant Protection Convention (IPPC), Pest Risk 
Analysis (PRA) includes three stages: initiation, pest risk assessment and pest risk 
management. Initiating the PRA process invol ves identifying pests and pathways of 
concern and defining the PRA area. Pest risk assessment provides the scientific basis 
for the overall management of risk. Pest risk management is the process of 
identifying and evaluating potential mitigation measures which may be applied to 
reduce the identified pest risk to acceptable levels and selecting appropriate 
measures.  
   
This Risk Management Document (RMD) includes a summary of the findings of a 
pest risk assessment and records the pest risk management proce ss for the identified 
issue.  It is consistent with the principles, terminology and guidelines provided in the 
IPPC standards for pest risk analysis which may be found at https://www.ippc.int/ . 
 
 
 
 
 
 
 
2014 -01-23        RMD -13-08 (consultation)  
Page 2 of 14 TABLE OF CONTENTS  
 
1.0 Executive Summary  ................................ ................................ ................................ ............  3 
2.0 Purpose  ................................ ................................ ................................ ................................  3 
3.0 Scope  ................................ ................................ ................................ ................................ ... 3 
4.0 Definitions, Abbreviations and Acronyms  ................................ ................................ .........  3 
5.0 Background  ................................ ................................ ................................ .........................  4 
6.0 Pest Categorisation Summary  ................................ ................................ .............................  4 
6.1 Pest Biology  ................................ ................................ ................................ .....................  4 
6.1.1  Life History  ................................ ................................ ................................ ...............  4 
6.1.2  Host Range  ................................ ................................ ................................ ................  5 
6.1.3  Symptoms  ................................ ................................ ................................ .................  5 
6.2 Distribution  ................................ ................................ ................................ ......................  5 
6.3 Means of Dispersal and Spread ................................ ................................ ........................  6 
6.4 Potential for Establishment and Spread  ................................ ................................ ...........  6 
6.5 Potential Economic and Environmental Consequences  ................................ ...................  7 
7.0 Risk Management Considerations  ................................ ................................ ......................  8 
7.1 Phytosanitary Requirements Prior to the Implementation of Interim Measures  ..............  8 
7.2 Interim Phytosanitary Measures  ................................ ................................ ......................  8 
7.3 Treatment and Control Options for Hymenoscyphus pseudoalbidus  ...............................  9 
8.0 Risk Management Options  ................................ ................................ ................................ .. 9 
8.1  Option 1: Maintain the Status Quo – Do Not Add Hymenoscyphus pseudoalbidus  to the 
List of Pest s Regulated by Canada ................................ ................................ ...................  9 
8.2  Option 2: Regulate Hymenoscyphus pseudoalbidus  and Implement Phytosanitary 
Requirements for Ash Plant Material  ................................ ................................ ............  10 
9.0 Risk Management Recommendation  ................................ ................................ ................  11 
10.0  Stakeholder Communications  ................................ ................................ ...........................  11 
11.0  References  ................................ ................................ ................................ .........................  11 
12.0  Endorsement  ................................ ................................ ................................ .....................  14 2014 -01-23        RMD -13-08 (consultation)  
Page 3 of 14 1.0 Executive Summary  
 
Hymenoscyphus pseudoalbidus  (ash dieback) is a harmful  pathogen  affecting ash trees in 
Europe. The severity and the rapid spread of the disease, and recent data demonstrating the 
susceptibility of North American ash (Fraxinus  spp.) species to the disease ma ke it a pest of 
concern to Canada.  
 
The risk posed by H. pseudoalbidus  to Canada  was evaluated through a Canadian Food 
Inspection Agency ( CFIA ) Pest Categorisation. The categorisation concluded  that H. 
pseudoalbidus  meets the definition of a quarantine pe st and that its introduction into Canada 
could cause significant negative economic and environmental impacts.  It is expected that H. 
pseudoalbidus  could result in the death or decline of large numbers of ash trees in forests, parks 
and urban landscapes, as  well as in nurseries.  
 
Due to the significant threat posed by H. pseudoalbidus , the CFIA has implement ed interim 
phytosanitary measures  to mitigate the risk of introducing this pest to Canada. Since January 30, 
2013 , importation of ash ( Fraxinus  spp.) nursery stock, branches and seeds  that was previously 
permitted entry into Canada from infested countries have been prohibited . These measures are 
temporary until the regulatory status of H. pseudoalbidus  in Canada is decided.  Therefore, 
through  this Risk Management Document  (RMD) , the CFIA is seeking  stakeholder s input on two 
risk management options for H. pseudoalbidus . The first option propose s to maintain the status 
quo i.e. not to regulate Hymenoscyphus pseudoalbidus . The second option  proposes to r egulate 
Hymenoscyphus pseudoalbidus  and consequently, to implement p hytosanitary requirements for 
ash plant material . CFIA’s preferred option is No.2.  
 
2.0 Purpose  
 
The purpose of this document is to seek stakeholder input regarding two risk ma nagement 
options for the ash dieback pathogen, Hymenoscyphus  pseudoalbidus  (Queloz et al.). 
 
3.0 Scope  
 
This RMD examines  the risk associated with the introduction of the ash dieback pathogen , H. 
pseudoalbidus , into Canada, and outlines risk management opt ions for this disease.  
 
Information pertaining to current import requirements for specific plants or plant products may 
be obtained from the CFIA ’s Automated Import Reference System ( http://airs -
sari.inspection.gc.ca/airs_external/english/decisions -eng.aspx ).  
 
4.0 Definitions, Abbreviations and  Acronyms  
 
Definitions for terms used in this document can be found in the Plant Health Glossary of Terms 
at http:// www.inspection.gc.ca/plants/plant -
protection/directives/glossary/eng/1304730588212/1304730789969  or the IPPC Glossary of 
Phytosanitary Terms at https://www.ippc.int . 
 2014 -01-23        RMD -13-08 (consultation)  
Page 4 of 14 5.0 Backgroun d 
 
Ash diebac k, caused by H. pseudoalbidus , is a serious emerging plant pest attacking ash trees in 
Europe. Since its detection in Poland and Lithuania in the early 1990s, this pathogen has spread 
across Europe , where it causes mortality of European ash trees. The dise ase is characterised by a 
rapid dieback of the crown, associated with the presence of cankers or lesions girdling the 
affected plant parts , which usually leads to plant death.  
 
Hymenoscyphus pseudoalbidus , often  referred to as Chalara fraxinea,  was recentl y found to be 
affecting some  native  North American ash tree species  planted in Europe.  The new host range for 
the pathogen now includes the native North American species Fraxinus  nigra, F. pennsylvanica  
and F. americana , as well as  F. mandschurica , native to Asia . This expanded host range has 
added to the concern that if the pathogen w ere to be introduced and become established in North 
America, it might cause significant harm to North American Fraxinus species.  
 
In light of the severity and rapid spread of the disease, and reports of the sensitivity of North 
America n Fraxinus  spp., a Pest Categorisation was completed by the CFIA to evaluate the risk 
posed by H. pseudoalbidus  to Canada.  The Pest Categorisation conclude d that H. pseudoalbidus  
meets the definition of a quarantine pest , and its introduction into Canada could cause significant 
negative economic and environmental impacts.  
 
6.0 Pest Categorisation  Summary  
 
The CFIA’s Pest C ategori sation for Hymenoscyphus pseudoalbidus  was completed in  November 
2012  (CFIA, 2012) . The following sections present the highlights of the categorisation.  
 
6.1 Pest Biology  
6.1.1  Life History  
Chalara fraxinea  is the asexual (anomorphic) stage of the fungus Hymenoscyphus pseudoalbidus  
which is considered to be the se xual (teleomorph) stage  of the disease .  Initially, the teleomorph 
was reported to be H. albidus , which was considered to be non -pathogenic, saprotrophic, native 
and widespread in Europe. Further molecular analysis revealed that the sexual stage was actual ly 
a new species which was named H. pseudoalbidus .  Hymenoscyphus pseudoalbidus  produces the 
infective sexually -produced ascospores and is considered to be responsible for the ash dieback 
disease.  Therefore, according to the one fungus, one name principle adopted by the International 
Code of Nomenclature for algae, fungi and plants, the ash dieback disease should be referred to 
as H. pseudoalbidus . 
 
The biology of the fungus is not yet fully understood ; however, observations in Europe have 
suggested that th e pathogen may enter ash trees through the leaves, in particular, the leaf 
petioles, which may enable the pathogen to subsequently grow into the vascular system  of shoots 
(McKinney et al., 2011; Timmermann et al., 2011). Reproductive structures of the sexu al state, 
H. pseudoalbidus , usually appear on previous year’s leaf litter, but  occasionally develop on dead 
shoots of young ash seedlings in nurseries, as well as on dead, broken shoots and twigs in contact 
with the ground (Timmermann et al., 2011).  
 2014 -01-23        RMD -13-08 (consultation)  
Page 5 of 14 6.1.2  Host Range  
Fraxinus  is the only genus know n to be affected by H. pseudoalbidus . Fraxinus  spp. originating 
from North America, Europe and Asia have been found  to be  susceptible to the pathogen (Table 
1). 
 
Table 1. Ash  species  (Fraxinus  spp.) know n to be host of  Hymenoscyphus pseudoalbidus . 
 
Origin  Scientific name  Common name  
North American  Fraxinus americana  White ash  
F. nigra  Black ash  
F. pennsylvanica  Green or red ash  
European  F. angustifolia  Narrow -leaf ash  
F. excelsior  European ash, common ash  
F. ornus  Flowering ash  
Asian  F. mandschurica  Manchurian ash  
 
6.1.3  Symptoms  
Hymenoscyphus pseudoalbidus  is characterised by a rapid dieback of the crown, associated with 
the presence of cankers or lesions girdling the affected plant parts, u sually leading to tree death 
(Kowalski and Holdenrieder , 2009; DEFRA, 2012). Symptoms of the disease occur in the bark 
and vascular system of shoots, twigs, branches and stems, as well as on leaves of ash trees 
(Timmermann et al., 2011). The most obvious d isease characteristics are: w ilting, discoloration 
and premature shedding of leaves ; dieback of shoots, twigs and branches ; necrosis of bark, 
leaves and buds ; necrotic cankers in the bark, shoots and branches ; a brown to grey 
discolouration of the inner ba rk; and discoloration of the wood (Bakys et al., 2009; Goudet et al. , 
2012; Timmermann et al., 2011). The appearance of small necrotic lesions on leaf petioles and 
leaflet veins are the first indication of infection (Timmermann et al., 2011). The fungus ha s been 
occasionally detected in roots, but only when the stem was also infected (Schumacher et al., 
2010). Diseased trees react with prolific formation of epicormic shoots (Kirisits et al., 2008). The 
fungus has also been linked to basal stem necrosis (Lan ger and Werres , 2013).  
 
6.2 Distribution  
Since its emergence in Poland , the disease has rapidly progressed across Europe, where, to date, 
the disease has been observed in, or reported from, the following countries : Austria, Bel gium, 
Belarus, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Hungary, 
Ireland, Italy,  Latvia, Lithuania, Netherlands, Norway, Poland, Romania, Russia, Slovakia,  
Slovenia, Sweden, Switzerland , Ukraine  and the U nited Kingdom  (Timmerman n et al., 2011) .  
 
The disease has also been reported outside of Europe . A recent p ublication describes the 
Japanese fungus Lambertella albida as conspecific with H. pseudoalbidus , suggesting that the 
correct name of L. albida , which had previously been reported from the petioles of the Asian ash 
species Fraxinus mandshurica in Japan , is actually H. pseudoalbidus (Zhao et al., 2012). 2014 -01-23        RMD -13-08 (consultation)  
Page 6 of 14 Similarly, H. pseudoalbidus was reported from decomposing leaves of F. mandschurica in China 
in 2013 (Zheng et al. , 2013). No  symptoms of disease were observed on the ash trees in China, 
strengthening the earlier belief  that the pathogen was introduced into Europe from Asia  as some 
Asian ash species such as  Manchurian Ash, planted as ornamental species in Europe, appeared 
immune to the disease  (Coghlan, 2012).  
 
6.3 Means of Dispersal and Spread  
The pathogen can be carried through trade via Fraxinus  spp. b ark, leaves, roots, stems, branches, 
seeds and wood. Movement of infected host material, such as Fraxinus spp. nursery stock, 
appears to be primary pathway for long-distance spread of the disease.  The recent discovery  in 
England nursery plants infected with  H. pseudoalbidus , which were imported directly from other 
nurseries in continental Europe (the Ne therlands), indicates that the pathogen is spread long -
distance via the plants for planting pathway (DEFRA, 2012). As well, the pathogen was shown 
to be able to produce conidia from infected wood (Husson et al., 2012), suggesting that untreated 
ash logs or  related wood products, such as firewood and woodchips, may be able to carry the 
pathogen  over long distances and act as pathways of introduction into disease -free areas.  
 
In Europe, the pathogen is thought to also be spreading naturally over long distanc es via wind -
borne  sexual spores ( ascospores ) (Wingen et al. 201 3; Timmermann et al., 201 1). Sexual spores  
may also disperse via the movement of soil, water, or insect vectors, although no insect vectors 
have been identified to date (Prokrym and Neeley, 200 9; Timmermann et al., 2011). Seeds of 
declining F. excelsior trees have also been shown to carry the pathogen at low levels, although 
the effect of H. pseudoalbidus  on seed germination and seedling emergence is currently 
unknown (Cleary et al., 201 3). Inte rnational trade of Fraxinus seed collected from areas known 
to be infested may  therefore  serve as a potential pathway for the introduction of this pathogen 
(Cleary et al., 201 3). 
 
6.4 Potential  for Establishment and S pread  
Host species suitable for establi shment and spread of H. pseudoalbidus  are present in Canada . 
These include F. nigra (black ash) , F. pennsylvanica (green or red ash) and  F. americana  (white 
ash) (Drenkhan and Hanso, 2010), all of which are known to be susceptible to the fungus.   
 
In Europ e, the North American black ash species, F. nigra , was severely affected by H. 
pseudoalbidus . Fraxinus nigra  commonly occurs  in Canada  in northern swampy woodlands from 
eastern Manitoba into the Atlantic Provinces including Newfoundland (Farrar, 1995). Fraxinus  
pennsylvanica, was moderately affected  in Europe , with symptoms similar to F. nigra , but with 
less evidence of dead shoots within the canopy. It is the most widely distributed ash in Canada, 
ranging from Saskatchewan to Nova Scotia. Fraxinus  americana  was the least affected  by the 
fungus  in Europe,  showing signs of wilting leaves but only minor dieback of shoots and twigs 
and bark necrosis (Drenkhan and Hanso, 2010). White ash is an eastern species and the most 
common native ash in Canada (Fa rrar, 1995). Fraxinus  excelsior  is considered to be highly 
susceptible to the fungus. It was introduced in North America but it has a relatively limited 
distribution in the Eastern U .S. and Canada  (Prokrym and Neeley, 2009).  
 2014 -01-23        RMD -13-08 (consultation)  
Page 7 of 14 Other species of ash in Canada  include F. quandrangulata  (blue ash), F. latifolia  (Oregon ash) 
and F. profunda  (pumpkin as h). There is currently no data available on the ir susceptibility to H. 
pseudoalbidus .  
 
The known distribution of the fungus includes parts of southern, central, northern and north-
eastern Europe which lie within plant hardiness zones 3 to 10  (NAPPFAST , 2012 ). The 
geographic range of the host Fraxinus species growing in Canada lie predominantly within 
NAPPFAST climate Zones 3 to 8, well within the climatic range of t he countries in which the 
pathogen is known to occur. Southern  and central areas of Saskatchewan, Manitoba, Ontario, 
Quebec, New Brunswick, Nova Scotia and Prince Edward Island, where either native F. 
americana , F. nigra  or F. pennsylvanica  trees grow, wou ld be expected to have climatic 
conditions conducive to disease development, should the pathogen be introduced into Canada.  
 
6.5 Potential Economic and Environmental Consequences  
If introduced into Canada, it is expected that H. pseudoalbidus  could result  in the death or 
decline of large numbers of ash trees in forests, parks and urban landscapes, as well as in 
nurseries. This could lead to significant negative economic and environmental impacts.  
 
Hymenoscyphus pseudoalbidus  symptoms would be highly undes irable aesthetically , if the 
pathogen were to infect urban ash tree populations. In urban environments , symptoms of the 
disease may lead to the removal and replacement of affected ash trees at considerable costs ; the 
average monetary value of urban trees h as been estimated at $700 per tree (Kenney and Idziak, 
2000). This value represents only the replacement costs and does not reflect the benefit to society 
provided by trees in urban environments. In addition, trees in urban environments provide a 
number of  environmental benefits such as helping to remove gaseous air pollution, energy 
conservation (heating and cooling costs), storm -water attenuation, noise buffering, providing 
wildlife habitats, increas ing property values, enhanc ing aesthetics, protection fr om wind and 
psychological well -being (Rosen and Kenney, 2003 ). These benefits could be negatively 
impacted due to a loss of trees in urban environments (Kenney and Idziak, 2000; Rosen and 
Kenney, 2003 .).  
 
Fraxinus americana  is the most common native ash i n Canada and also the most commercially 
valuable species , used in the manufacture of wood products such as handles, sporting goods such 
as hockey sticks and baseball bats, furniture, baskets and kitchen cabinets (Farrar, 1995; Panshin 
and de Zeeuw, 1970). White ash is also used for veneer and hardwood flooring products. Dead or 
dying trees are not used in the manufactur e of wood products for which ash wood is favoured 
(Panshin and de Zeeuw, 1970). Furthermore, the discoloration of the wood caused by the fun gus 
would make wood from affected ash trees undesirable and unmarketable for manufactured wood 
products.  Canada’s ash wood export market would be negatively impacted as this pathogen could 
pose a risk in the more extensive and diverse deciduous forests of the U .S., Canada’s largest 
trading partner (Shore, 1992 ). Hymenoscyphus pseudoalbidus  is considered a reportable 
(quarantine) pest in the U .S. (USDA -APHIS, personal communication, 2012) . 
 
A change in forest biodiversity may also occur due to a change in fo rest composition as a result 
of a large decline in ash trees (USDA -APHIS/ARS/FS, 2010). Ash trees often fill gaps in the 2014 -01-23        RMD -13-08 (consultation)  
Page 8 of 14 forest , providing shade for the forest floor; ash is one of the few native trees able to out -compete 
weeds that prevent other species f rom becoming established (USDA -APHIS/ARS/FS, 2010).  
 
7.0 Risk Management Considerations  
 
7.1 Phytosanitary Requirement s Prior to the Implementation of Interim Measures  
The introduction of the H. pseudoalbidus  to Canada would most likely occur through the  
importation of ash wood products, nursery stock, branches and seeds.  Phytosanitary requirements 
for the importation of ash plant material had previously been put in place to mitigate the risk 
posed by other quarantine pests. Phytosanitary requirements in place prior to the implementation 
of the interim phytosanitary measure s for areas other than continental U.S. are described below.  
 
Ash wood products  from foreign source s have been  subject to phytosanitary requirement to 
mitigate the entry of various quara ntine pests  as outline d in D-02-12, Import requirements for 
non-processed wood and other non -propagative wood products, except solid wood packaging 
material, from all areas other than the continental United States  (CFIA, 2011). In general, ash 
wood product s must be free from bark and heat treated or fumigated with methyl bromide as per 
requirements described in the D -02-12, or prior approval is required.  
 
Ash plant s and plant parts for planting have been  Not Approved  Pending Pest Risk Analysis 
(NAPPRA) as per directive D -08-04, Plant protection import requirements for plants and plant  
parts for planting : preventing the entry and spread of regulated plants pests associated with the 
plants for planting pathway , from all countries except the U.S., Germany and t he Netherlands  
(CFIA, 201 3). Ash plant s and plant parts from Germany and the Netherlands have been  required 
to be accompanied by an Import Permit and a Phytosanitary Certificate.  As of January 2013, 
prior to the implementation of the interim phytosanitary measures, there were a very limited 
number of valid Import P ermit s for the import of rooted ash plants , and only for a  diameter equal 
to or less than 10 mm .  
 
From areas other than the continental U.S. , fresh ash decorative branches  have been allowed 
entry  only from Germany and the Netherlands if accompanied by  a Phytosanitary Certificate and 
an Import Permit. However, there were no valid  Import Permit s in the CFIA’s records  as of 
January 2013 . 
 
Dried ash branches larger than 1.5 cm imported from all areas other than the continental  U.S. 
have been  required to be fumigated with  methyl bromide ( CFIA, 2011 ). Dried branches smaller 
than 1.5 cm have not been subject to any specific phytosanitary requirements.  
 
The importation of ash s eeds previously require d an Import Permit . Again, there were very few 
valid I mport Permits for ash seeds in the CFIA’s records as of January 2013.  
 
7.2 Interim Phytosanitary Measures  
On January 30, 2013, due to the important threat posed by H. pseudoalbidus , the CFIA 
implement ed interim phytosanitary measures prohibiting the importation of ash ( Fraxinus  spp.) 
nursery stock and fresh branches from the Netherlands and Germany as well as seeds , in vitro 
plants  and dried branches from all  countries  infested with H. pseudoalbidus . The Auto mated 2014 -01-23        RMD -13-08 (consultation)  
Page 9 of 14 Import Reference System (AIRS) was updated to reflect this and, whe re applicable, Import 
Permits were  amended or cancelled. A World Trade Organisation (WTO) Notification of 
Emergency Measures was published on January 23, 2013. These measures are temp orary until 
the regulatory status of H. pseudoalbidus  in Canada is decided.  
 
7.3 Treatment  and Control  Options  for Hymenoscyphus pseudoalbidus   
There are currently no pesticide products registered for H. pseudoalbidus  in Canada , and limited 
or no pesticide s are registered i n other countries (PMRA, personal  comm unication, 2013 ).  
 
Research into naturally resistant trees ha s been carried out on the European species F. excelsior  
(Kjaer et al., 2012; McKinney et al. , 2011) . A very limited number of trees in the  population 
have been found to show a partial resistance to the pathogen.  We can hypothesize that some level 
of resistance may be present in North American species.  
 
8.0 Risk Management Options  
 
Through this RMD, t he CFIA is soliciting  stakeholders input o n the following proposed risk 
management option s for H. pseudoalbidus . The option chosen will replace the interim 
phytosanitary measures implemented on January 30, 2013.  
 
8.1  Option 1: Maintain the  Status Q uo – Do Not Add Hymenoscyphus pseudoalbidus  to 
the List of Pest s Regulated by Canada  
Under this option, the CFIA would not regulate H. pseudoalbidus . Interim emergency measures 
would be cancelled.  No additional phytosanitary requirements would be applied to host material  
to mitigate the risk of introduci ng H. pseudoalbidus  into Canada . 
 
  Advantage s: 
 No additional requirements  restricting  the importation of Fraxinus  spp. from infested 
countries.  
 No regulatory action (e.g. official control, eradication, non -compliance) would be 
taken by the CFIA to limit t he impact of this pathogen if detected in Canada.  
 
Disadvantages : 
 If introduced into Canada, H. pseudoalbidus  could result in the death or decline of 
large numbers of ash trees both in forests, parks and urban landscapes, as well as in 
nurseries leading t o significant negative economic  (domestic and export)  and 
environmental impacts.  
 There is currently no known treatment option available to control the incidence and 
spread of H. pseudoalbidus  if introduce d in Canada.  
 In the North American context , where emerald ash borer is spreading rapidly through 
the continent and represent s a very serious  threat to ash resource s, adding a n 
additional pest burden  could compromise the su stainability of this resource . 
 2014 -01-23        RMD -13-08 (consultation)  
Page 10 of 14 8.2  Option 2: Regulate Hymenoscyphus pseudoalbidus  and Implement P hytosanitary 
Requirements for A sh Plant Material  
Phytosanitary requirements for host material would be modified  to take into account the risk 
posed by H. pseudoalbidus . The following  additional  import conditions  would be applied  to 
Fraxinus  spp. plant material : 
 Nursery stock (rooted and unrooted) from  all infested countries, including  the 
Netherlands and Germany , would be prohibited entry into Canada.  
 In vitro plantlets from the Netherlands and Germany would be required to be 
accompanied by a Phytosanitary Certificate attesting that the plant material has been 
tested and found free of H. pseudoalbidus . In vitro plantlets from all other infested 
countries will remain NAPPRA.  
 Fresh and dried branches (including wreath s) of all diameter s and see ds originating 
from infested countries would be prohibited entry into Canada.  
 
The c ountries c urrent ly infested with H. pseudoalbidus  countries are listed in section 6.2 of this 
RMD. In addition to those countries,  CFIA would also consider all other count ries from the 
European Union  to be potentially infested  in view of  the wide distribution of this disease  in 
Europe . 
 
The CFIA believe that the currently available  scientific data do es not support  the development of 
phytosanitary measures for ash plants and  plant parts for planting ( i.e. rooted and unrooted 
plant s, fresh and dried branches and seeds ) that would mitigate the risk associated with H. 
pseudoalbidus to an acceptable level. As more information on the disease becomes available, the 
CFIA may be able  to consider pest -free areas and systems approach es as satisfactory mitigation 
measures for countries from which import  was previously approved i.e. the Netherlands and 
Germany. All other infested countries  (currently NAPPRA)  would still be subject to a fu ll Pest 
Risk Analysis t o determine if they would be admissible . For the U.S., p hytosanitary requirements 
would remain unchanged  as H. pseudoalbidus  is not known to occur in the U.S.  
  
Phytosanitary requirement s for ash wood products (e.g. sawn wood ) would  continue to require a 
Phytosanitary Certificate attesting that the wood ha s been either heat -treated or fumigated with 
methyl bromide. It is currently believed that th ese two treatments adequately mitigate the risk of 
introducing H. pseudoalbidus  into Cana da via these wooden products  and no further action is 
required . Prior approval would still be required for any other ash wood products.  
 
Advantages:  
 By regulating H. pseudoalbidus , the CFIA would have the authority to require 
phytosanitary measures for hos t material and to respond to incursion s by applying 
official control measures.  
 Implementing phytosanitary requirements for host material of H. pseudoalbidus  will 
mitigate the  risk of introduc ing this pathogen to Canada and help preserve our ash 
wood  and p lant export market.   
 Further prevent the entry into Canada of a potentially ineradicable pest.  
 Strengthens the North American Perimeter Approach as the U.S. regulates H. 
pseudoalbidus . 2014 -01-23        RMD -13-08 (consultation)  
Page 11 of 14  
Disadvantages:  
 Canadian i mporters would not be allowed to import ash nursery stock, branches and 
seeds from countries  infested with H. pseudoalbidus . 
 Resources  may be  needed by the CFIA  to enforce the regulation if non -compliance s 
are found  in imported products  and to administer and enforce Official Control 
(eradication or containment measures ). 
 In the future, r esources may be needed by the CFIA to review proposals for pest free 
areas or systems approaches submitted by infested countries wishing to export ash 
plant material to Canada.  
9.0 Risk Management Recommendation   
 
After critical evaluation of Hymenoscyphus pseudoalbidus  (ash dieback pathogen ), along with  
the risks associated with its potential introduction into Canada, the CFIA’s recommended risk 
management option No. 2.  The CFIA will consider all comments re ceived regarding the options 
proposed, including the recommended option before a final risk management decision is made.  
   
10.0 Stakeholder Com munications  
 
The following trading partners and stakeholders will be notified of changes in import 
requirements resulting from the risk management decision:  
 Trading partners (including a World Trade Organization notification, the International Plant 
Protection Convention Phytosanitary Portal, etc.);  
 CFIA  Program Officers, inspection staff, Import Service Centers, et c.;  
 Other government organizations (e.g. the Canadian Border Services Agency); and  
 Industry stakeholders . 
 
11.0 References  
 
Bakys R, R Vasaitis, P Barklund, IM Thomsen , J Stenlid. 2009. Occurrence and pathogenicity  
of fungi in necrotic and non -symptomati c shoots of declining common ash ( Fraxinus excelsior ) 
in Sweden. Eur opean  Journal of  Forest Res earch  128(1): 51-60. 
 
Cleary, MR, N Arhipova, T Gaitnieks, J Stenlid, and R Vasaitis.  2013. Natural infection of 
Fraxinus excelsior  seeds by Chalara fraxinea . Forest Pathology  43(1): 83-85. 
 
Canadian Food Inspection Agency (CFIA). 2011. Directive D -02-12: Import requirements for 
non-processed wood and other non -propagative wood products, except solid wood packaging 
material, from all areas other than the continent al United States (July 18th, 2011 (6th Revision))  
 
Canadian Food Inspection Agency (CFIA). 2012. Pest Categorisation: Chalara fraxinea  
(Hymenoscyphus pseudoalbidus ) (Ash Dieback Pathogen). Plant Health Risk Assessment Unit, 
Plant Health Science Division. O ttawa, Ontario. April 16 2012, Revised November 16, 2012.  
 2014 -01-23        RMD -13-08 (consultation)  
Page 12 of 14 Canadian Food Inspection Agency (CFIA). 2013. Directive: D -08-04: Plant Protection Import 
Requirements for Plants and Plant Parts for Planting ( November  25th, 201 3 (2nd Revision))  
 
Coghlan, A. 2012 . Are Europe's ash trees finished?. New Scientist. 31 October 2012. Online 
publication [http://www.newscientist.com/article/dn22449 -are-europes -ash-trees -finished.html  ] 
 
Department for Environment, Food & Rural Affairs  (DEFRA ). 2012. Rapid Risk Assessment : 
Rapid assessment of the need for a detailed Pest Risk Analysis for Chalara fraxinea . Online 
publication. 
[http://www.fera.defra.gov.uk/plants/plantHealth/pestsDiseases/documents/chalaraFraxinea.pdf  ] 
Accessed November 6th, 2012.  
 
Drenkhan R  and M Hanso. 2010. New host species for Chalara fraxinea  . New Disease Reports 
22, 16. 
 
Farrar, JL. 1995. Trees in Canada. Fitzhenry & Whiteside Limited and the Canadian Forest 
Service Natural Resources Group. 502 pp.  
 
Forestry Commission ( Great Britain ). 2012. Chalara  dieback of ash ( Chalara fraxinea ). Online 
publication . [http://www.forestry.gov.uk/chalara  ]. Accessed November 13th, 2012.  
 
Goudet, M and D Piou. 2012. Ash dieback or chalarose - what do we know? Revue Forestiere 
Francaise. Vol. 64(1): 27 -40.  
 
Husson, C,  O Cael, JP Grandjean, LM Nageleisen and B Marcais, 2012. Occurrence of 
Hymenoscyphus pseudoalbidus on infected ash logs. Plant Pathology  61(5): 889 -895. 
 
Kenney, WA and C Idziak. 2000. The State of Canada's Municipal Forests - 1996 to 1998. 
Forestry Chron icle 76(2): 231 -234. 
 
Kirisits T, M Matlakova, S Mottinger -Kroupa, and E Halmschlager. 2008. Involvement of 
Chalara fraxinea in Ash Dieback in Austria. Forstschutz Akuell 44.  
 
Kjaer, ED, LV Mckinney, LR Nielsen, LN Hansen and JK Hansen. 2012. Adaptive pote ntial of 
ash ( Fraxinus excelsior ) populations against the novel emerging pathogen Hymenoscyphus 
pseudoalbidus . Evolutionary Applications  5(3): 219 -228. 
 
Kowalski , T and O Holdenrieder. 2009. The teleomorph of Chalara fraxinea , the causal agent of 
ash dieba ck. Forest Pathology 39: 304 -308. 
 
Langer, G. and S. Werres.  2013.  Fungi associated with stem necrosis on ash trees infected with 
Hymenoscyphus pseudoalbidus  in Schleswig -Holstein . (Abstract) COST Action FP1103  
FRAXBACK 4th MC Meeting & Workshop “Frontie rs in ash dieback research”, 4 -6th of 
September 2013, Sankt Gertrud Konferens, Malmö, Sweden  
 2014 -01-23        RMD -13-08 (consultation)  
Page 13 of 14 Marčiulynienė D., M. Clear, D. Shabunin, J. Stenlid and R. Vasaitis. 2013. Detection of 
Hymenoscyphus pseudoalbidus  in Primorye region, Far East  Russia . (Abstract) COST Action 
FP1103 FRAXBACK 4th MC Meeting & Workshop “Frontiers in ash dieback research”, 4 -6th of 
September 2013, Sankt Gertrud Konferens, Malmö, Sweden  
 
McKinney LV, LR Nielsen, JK Hansen, and ED Kjær. 2011. Presence of natural genetic 
resistance in Fraxinus excelsior (Oleraceae) to Chalara fraxinea (Ascomycota): an emerging 
infectious disease . Heredity 106:  788–797.  
 
NCSU/APHIS Plant Pest Forecast (NAPPFAST) . 2012. NAPPFAST Global Plant Hardiness 
Zones based on CFSR base data. North Carolina State University APHIS Plant Pest Forecasting 
System . August, 2012.  Online publication. [http://www.na ppfast.org ]  
 
Panshin AJ, C de Zeeuw. 1970. Tex tbook of wood technology. Vol. 1. Structure, identification, 
uses, and properties of the commercial woods of the United States and Canada. McGraw -Hill 
Book Company, Toronto, pp. 705.  
 
Pautasso M , G Aas,  V Que loz and  O Holdenrieder. 2013.  European ash ( Fraxinus excelsior ) 
dieback – A conservation biology challenge. Biological Conservation 15 8: 37-49. 
 
Prokrym, DR and AD Neeley. 2009. New Pest Advisory Group (NPAG) Report: Chalara 
fraxinea T. Kowalski: Ash dieba ck. United States Department of Agriculture , Center for Plant 
Health Science and Technology , Plant Epidemiology and Risk Analysis Laboratory . 
 
Rosen, MR and WA Kenney. 2003 . Urban Forestry Trends in Canada. Online publication.  
[http://www.fao.org/docrep/AR TICLE/WFC/XII/0752 -B1.HTM ] 
 
Shore TL. 1992. Ambrosia beetles. Forest Pest Leaflet #72, Canada -British Columbia 
Partnership Agreement on Forest resource Development: FRDA II.  
 
Schumacher J., R Kehr and S. Leonhard. 2010. Mycological and histological invest igations of 
Fraxinus excelsior  nursery saplings naturally infected by Chalara fraxinea . Forest Pathology 40: 
419-429. 
 
Timmermann V, I Borja, AM Hietala, T Kirisits and H Solheim. 2011. Ash dieback: pathogen 
spread and diurnal patterns of ascospore dispers al, with special emphasis on Norway. EPPO 
Bulletin, 41:  14–20. 
  
USDA –APHIS/ARS/FS. 2010. Emerald Ash Borer, Agrilus planipennis Fairmaire,  
Biological Control Release Guidelines. USDA –APHIS –ARS -FS, Riverdale, Maryland.  Online 
publication. [http://na.fs.fed .us/fhp/eab/ar/ar.shtm  ]. Accessed November 2012.  
 
Wingen LU, MW Shaw  and JKM Brown . 2013. Long -distance dispersal and its influence on 
adaptation to host resistance in a heterogeneous landscape. Plant Pathology 62(1): 9 -20. 
 2014 -01-23        RMD -13-08 (consultation)  
Page 14 of 14 Zhao  Y-J, T Hosoya, H -O Baral,  K Hosaka and M Kakishima. 2012. Hymenoscyphus 
pseudoalbidus , the correct name for Lambertella albida reported from Japan. Mycotaxon. 122: 
25-41. 
 
Zheng, H. -D. and W. -Y. Zhuang. 2013. Hymenoscyphus albidoides sp. nov. and H. 
pseudoalbidus from China. Mycological P rogress DOI: 10.1007/s11557 -013-0945 -z. 
[http://link.springer.com/article/10.1007%2Fs11557 -013-0945 -z/fulltext.html  ]. Accessed 
January 16, 2014 . 
 
12.0 Endorsement  
 
Approved by:  
 
 
_________________________________________  
Chief Plant Health Officer  
 
Signat ure of the Chief Plant Health Officer is required only on completion of the pest risk 
management process, to indicate approval of the final decision.  This section is included in the 
RMD after stakeholder consultation has occurred and a final decision is m ade.