RMD -18-01: Pest Risk Management Document – Deregulation of 
Anisogramma anomala , causal agent of eastern filbert blight  
 
 
 
(Original ) 
 
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 involves identifying pests and pathways of concern and defining t he 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 a cceptable 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 decision process for deregulation of 
Anisogramma anomala  (Peck) E. M üll. It is consistent with the principles, terminology and 
guidelines provided in the IPPC standards for pest risk analysis which may be found at the 
International Plant Prote ction Convention website . 
Table of Contents  
Executive Summary  ................................ ................................ ................................ .........................  2 
1.0 Purpose  ................................ ................................ ................................ ................................ ..... 2 
2.0 Scope  ................................ ................................ ................................ ................................ .........  3 
3.0 Definitions, Abbreviations and Acronyms  ................................ ................................ ................  3 
4.0 Background  ................................ ................................ ................................ ...............................  3 
5.0 Pest Risk Assessment Summary  ................................ ................................ ................................  4 
5.1 Pest Biology  ................................ ................................ ................................ ...........................  4 
5.2 Pathways  ................................ ................................ ................................ ...............................  4 
5.3 Economic Con siderations  ................................ ................................ ................................ ...... 5 
6.0 Risk Management Considerations  ................................ ................................ ............................  5 
6.1 Standards of the International Plant Protection Convention  ................................ ...............  5 Page 2 of 9 
 6.2 Plant Protection Regulations and Directive D -00-03 ................................ ............................  5 
6.3 Surveillance and Distribution  ................................ ................................ ................................  6 
6.4 Eradication/Containment  ................................ ................................ ................................ ...... 6 
6.5 Potential Environmental and Economic Consequences  ................................ .......................  6 
6.6 Pest Status in the United States  ................................ ................................ ............................  6 
6.7 British Columbia Hazelnut Industry Considerations  ................................ .............................  7 
7.0 Risk Management Decision  ................................ ................................ ................................ .......  7 
8.0 References  ................................ ................................ ................................ ................................  8 
 
Executive Summary  
 
Anisogramma anomala  is a fungal pathogen native to eastern North America and is an 
impediment to the commercial production of European hazelnuts  (Corylus  avellana ). 
Historically, commercial production of hazelnuts was a profitable , low -input crop west of the 
continental divide , where A. anomala  was absent . In the late 1960s, A. anomala  was detected 
in Washington State  and subsequently spread to British Columbia  where it was first detected in  
2002  (Davison and Davidson 1973,  Sabaratnam et al . 2009) .  
 
In 1975, Canada put regulations  in place  to prevent human -assisted spread of A. anomala  into 
British Columbia.  More recently,  under  Directive D-00-03: Import requirements from the United 
States and domestic movement requirements for material to prevent the introduction of eastern 
filbert blight into British Columbia,  import ation  of Corylus  spp.  from infested origins  was 
restricted  to in vitro  plantlets , thereby  permit ting access to varieties of Corylus  that are 
resistant to A. anomala , while limiting the opportunities for human -assisted  spread  of the pest .  
 
In the years since 200 2, A. anomala  devastated the commercia l hazelnut production area of 
British Columbia . However , the hazelnut industry across Canada is currently undergoing a 
revival, in part based on access to new varieties of Corylus  spp. bred for resistance to A. 
anomala . Resistance is not absolute, and resistant plants are only part of an easte rn filbert 
blight management program that must be implemented for successful commercial production  
(O’Dell 2018, Psch eidt et al . 2017 ). 
 
Anisogramma anomala  can no longer be considered a regulated pest in Canada due to its 
widespread distribution and the lack of control measures aimed at containing or eradicating it. 
The CFIA will take the necessary steps to deregulate this pest, including removing it from 
Schedule II of the Plant Protection Regulations  and from the List of Pests Regulated by Canada . 
Directive D -00-03 will also be repealed.  
 
1.0 Purpose  Page 3 of 9 
  
The purpose of this document is to record risk management considerations and inform 
stakeholders of the Canadian Food Inspection Agency’s (CFIA’s ) decision to deregulate  
Anisogramma anomala  (Peck) E. Müll.  
 
2.0 Scope  
 
This RMD provides the history and rationale for the CFIA’s decision to deregulate A. anomala . 
 
Information pertaining to current import requirements for specific plants or plant products may 
be obtained from the Automated Import Reference System ( www.inspection.gc.ca/airs ).  
 
3.0 Definitions, Abbreviations and Acronyms  
 
Definitions of terms used in this document can be found in the International Standard for 
Phytosanitary Measures 5: Glossary of phytosanitary terms  or the Plant Health Glossary of 
Terms . 
 
4.0 Background  
 
Anisogramma anomala , the causal agent of eastern filbert blight , a disease of Corylus  spp. , is 
native to eastern  North Ame rica. Anisogramma  anomala  is nonlethal to  native species of 
Corylus , including  American hazelnut ( C. americana ) and beaked hazel or California hazel 
(Corylus cornuta ). European hazelnut ( C. avellana ), most commonly cultivated for the  
commercial  production of  hazelnuts , is highly susceptible to A. anomala , which is lethal to 
unmanaged trees .  
 
The historic absence of A. anomala  west of the Rocky Mountains permitted the establishment 
of a commercial hazelnut industry, starting in Oregon in the early 1900 s and in British Columbia 
in the 1930 s. 
 
In the 1920 s the Oregon and Washington imposed r egulatory measures to prevent the 
introduction  of A. anomala  (Barss 1930; Thompson 1930) . Canada put similar requirements in 
place in 1975  to protect British Columbia . Despite the efforts to prevent its spread into western 
North America, A. anomala  was introduced to Washington  State  in the late 1960 s (Davison and 
Davidson 1973) . The pathogen continued to  spread in the Pacific Northwest eventually reaching 
Oregon’ s Willamette Valley in 1986 (Mehlenbacher and Olsen 1996).  
 
In 200 2, the CFIA confirmed  the presence of A. anomala  in the British  Columbia Lower 
Mainland region for the first time. The CFIA  published a directive  (D-00-03) in 200 6 to allow  
growers in  British Columbia to import A. anomala -resistant Corylus  varieties developed in 
Oregon , while continuing to limit the risk of human -assisted  spread of the pathogen into British 
Columbia.  In 2007, the British Columbia Ministry of Agriculture (BCAGRI ) reported a further Page 4 of 9 
 detection of A. anomala  on Vancouver Island.  Since its initial introduction to British Columbia, 
A. anomala  has continued to spread within the province and is now present in all areas where 
hazelnuts are commercially produced.  
 
5.0 Pest Risk Assessment Summary  
 
A pest risk assessment  was originally completed on A. anomala  in 1991 (PRA 1991 -01) and 
updated in 1996 (PRA 1996 -14). Three additional assessments were  completed on specific 
aspects of the pest’s biology and its regulation  (PRA 1998 -69, 2014 -86, 2016 -73). 
 
5.1 Pest Biology  
 
Anisogramma anomala  is a fungal pathogen and the causal agent of eastern filbert blight. This 
pathogen  occurs only in North America and is associated with American hazelnut  (C. 
americana ) throughout its native range east of the Rocky Mountains  (Gleason and  Cronquist 
1991). On American hazelnut, A. anomala  is a nonlethal pathogen causing an insignificant 
canker , which typically ranges from 1 to 10 cm in length. In contrast, on European hazelnut (C. 
avellana ), this pathogen can cause cankers that expand at ra tes of up to 1 m per year. If left 
unmanaged, t he e xpanding cankers girdle the branches and limbs, resulting in canopy dieback 
and tree death within  5 to 12 years (Johnson et al . 1996).   
 
European hazelnut becomes susceptible to infect ion by A. anomala  only after budbreak, when 
vegetative buds initiate active growth in spring, and is most susceptible during leaf emergence 
and initial shoot elongation. Initial colonization occurs without obvious symptoms of disease for 
12 to 15 months. Cankers form durin g the spring of the second year of infection and continue 
to expand until late autumn when ascospores are released from mature perithecia . Ascospore s 
are released during periods of rain  and are dispersed by win d. 
 
Historically, A. anomala  was absent from w estern North America , until the pathogen was 
introduced to Washington State during the 1960s (Gottwald and Cameron  1980; Johnson et al . 
1996 ). Research into the development of A. anomala  resistance in Oregon has focused on 
developing Corylus  varieties suitable for cultivation in that region, where the genetic diversity 
and pathogenic variation of A. anomala  is believed to be less than in eastern North America  
(CFIA 2015 ; Muehlbauer 2017 ). Molnar et al. (2010) found that  some A. anom ala-resistant 
Corylus  varieties developed in western North America  expressed symptoms characteristic of 
eastern filbert blight  when cultivated in eastern North America . These observations support the 
idea that there are multiple strains of A. anomala , and that there is likely lower diversity  of 
strains in western North America compared to  eastern  North America.  
 
Currently, there are no regulatory diagnostic procedures capable of readily distinguishing 
between strains of A. anomala  and no catalogue of strain  distribution in North America.   
 
5.2 Pathways  
 Page 5 of 9 
 In addition to natural dispersal by wind, A. anomala  may also be spread by  human -assisted  
means, including the movement of infected plant parts such as  bark, wood, shoots, branches 
and trunks. Roots, foliage,  nuts and growing media associated with plants are not considered to 
be pathways for spread (CABI 201 8).  
 
5.3 Economic Consideration s 
 
Despite the CFIA’s regulations aimed at preventing the spread of A. anomala , the pest has 
established in all commercial production areas of Canada. The introduction and establishment 
of A. anomala  in British Columbia has contributed to  a shift in how hazelnuts are  commercially 
produced. A cr op that was once considered “low-input ” now requires active disease 
management  resulting in increased production costs . Oregon c ontinues to be a major hazelnut 
producing state, despite  the presence of  A. anomala  for more than 30 years. Effective disease 
management strategies have been developed  includ ing: scouting, reducing inoculum load, 
applying fungicides and planting disease -resistant varieties  (Pscheidt et al . 2017) .  
 
Research in eastern North America has continued to advance efforts in breeding resistant 
varieties  and new evidence suggests that some crosses of  A. anomala -resistant varieties from 
Oregon  can provide acceptable protection from at least some of the strains  of A. anomala  that 
are present in the east, although the m echanisms of resistance are  complex and require further 
investigation (Muehlbauer et al. 2018). Continued development of dise ase-resistant varieties 
may serve  to reduce production costs in the future.  
 
6.0 Risk Management Considerations  
 
6.1 Standards of the International Plant Protection Convention  
 
The CFIA is designated as Canada’s National Plant Protection Organization (NPPO) under the 
International Plant Protection Convention. As such, the CFIA’s actions are guided by a suite of 
International Standards for Phytosanitary Measures (ISPM). ISPM 5:  Glossary of Phytosanitary 
Terms  defines a quarantine pest as, “a pest of potential economic importance to the area 
endangered thereby and not yet present there, or present but not widely distributed and being 
officially controlled”  (IPPC 2017).   
 
6.2 Plant P rotection Regulations  and Directive D -00-03 
 
Anisogramma anomala  is currently listed in Schedule II of the Plant Protection Regulations  
(Restricted Movement within Canada), and is included in the List of Pests Regulated by Canada.       
 
Directive D -00-03 describes phytosanitary requirements specific to the prevention of human -
assisted  spread of A. anomala  to British Columbia. In brief, plants for planting from infested 
areas are prohibited; plants for planting from non -infested areas esta blished by annual survey 
may enter British Columbia , and in vitro  plantlets may enter British Columbia from both 
infested and non -infested areas.  Page 6 of 9 
  
The requirements described in D -00-03 were designed to address specific objectives. The first 
objective was t o prevent the human -assisted  spread of A. anomala  to British Columbia . The 
second was to prepare growers for the eventual natural spread of A. anomala  to British 
Columbia  by permitting access to resistant plants developed by hazelnut breeding programs, 
for example the program at Oregon State University.  
 
At the time D -00-03 was developed, resistance to A. anomala was viewed as an alternative to 
integrated pest management and a method to restore Corylus  production as a low -input crop. 
In the intervening years, Molnar et al . (2010) observed that several A. anomala -resistant 
Corylus  spp.  varieties , developed by the hazelnut breeding program at Oregon State University, 
were susceptible to A. anomala  strains pre sent in eastern North America. Based on this 
information, the CFIA considered revising directive D -00-03 to prevent the strains of A. anomala  
present in eastern North America from reaching British Columbia.  After considering all the 
elements that would be required in order to establish ‘official control’, the CFIA has determined 
that regulating A. anomala  at the strain level is not justified.   
 
6.3 Surveillance and Distribution  
 
In 2002 t he CFIA carried out a surve y to detect  the presence of A. anomala  and detected  the 
pathogen  for the first time  in the Lower Mainland region of  British Columbia . In 2007, BCAGRI  
detected the fungus on Vancouver Island.  Anisogramma  anomala  is now considered to be 
present in all areas of Canada  where European or American hazelnuts grow , with the exception 
of a few isolated poc kets in British Columbia’s Okana gan Valley, where the disease has not yet 
been reported.  
  
6.4 Eradication/ Containment  
 
Anisogramma  anomala  is naturally spread by wind -borne spores and cannot be eradicated or 
contained once it has established in an area.  
 
6.5 Potential Environmental and Economic Consequences  
 
Deregulation of A. anomala  is not expected to have a significant impact on the costs  associated 
with commercial hazelnut production because this pathogen is already present in all 
commercial hazelnut production areas of Canada. Deregulation of A. anomala  is expected to 
benefit the commercial hazelnut industry in British Columbia as  grower s will have increased 
access to new A. anomala -resistant germplasm.  
 
Deregulation of A. anomala  is not expected to have a significant environmental impact as this 
pathogen is nonlethal to native Corylus  species.  
 
6.6 Pest Status in the United States  
 Page 7 of 9 
 Anisogramma  anomala  is not regulated at the federal  level in the United States . However, two 
states, Oregon and Washington , have  implemented state regulations to prevent the 
introduction of strains of A. anomala  present in eastern North America  (Anonymous 2012; 
Brown 2014) . 
 
6.7 British Columbia Hazelnut Industry Considerations  
 
Over the past fifteen years t he hazelnut industry in British Columbia has lost nearly ninety 
percent of its orchards to eastern  filbert blight . In 2018 , BCAGRI  launched a 3 -year tree -removal 
and replanting program and a 2 -year disease surveillance and management program for 
hazelnuts. The intention of these programs is to replant disease -resistant varieties  originating 
from Oregon State . However, t he phytosanita ry import requirements that are in place to 
prevent the introduction of A. anomala  to British Columbia also limit the importation of 
hazelnut planting materials and are viewed as an impediment to the growth of British 
Columbia’s hazelnut sector . 
 
7.0 Risk Management Decision  
 
The CFIA has reviewed the available  scientific information and has made  the decision to  
deregulat e A. anomala . Anisogramma anomala  is present in all commercial hazelnut 
production areas of Canada, including British Columbia, and is also harboured by native species 
of Corylus  throughout North America . This pathogen is not under officia l control in British 
Columbia. Anisogramma  anomala  no longer meets internationally accepted  criteria to be 
considered a quarantine pest.  The decision to deregulate  A. anomala  is expected  to benefit  the 
hazelnut industry in British Columbia by improving access to  A. anomala -resistant hazelnut  
varieties .  
 
The CFIA intends to remove  A. anomala  from Schedule II of the Plant Protection Regulations  
during  the next regulatory revi sion process. Until this regulatory change is made, the following 
changes will serve to functionally deregulate A. anomal a. The CFIA will revoke directive D -00-
03: Import requirements from the United States and domestic movement requirements for 
material to prevent the introduction of Eastern filbert blight into British Columbia . In addition, 
the CFIA will not take regulatory ac tion to enforce item 14 (10) of Schedule II of the Plant 
Protection Regulations  as it pertain s to the domestic movement of filbert (Corylus  spp.) .  
 
As part of the deregulation  process , A. anomala will be removed from the List of Pests 
Regulated by Canada and the Automated Import Reference System  (AIRS) will be updated to 
reflect that th e importation of articles of Corylus  spp. are no longer subject to the requirements 
described in directive D -00-03. Importation of Corylus  spp. plants for planting from the 
continental United States  and the Netherlands  will require a permit to import and a 
phytosanitary certificate. Corylus  spp. plants for planting from the rest of the world are 
considered Not Authorized Pending a Pest Risk Analysis  (NAPPRA). Trading partners will be 
notified through the World Trade Organization that A. anomala  is no longer a pest regulated by 
Canada.  Page 8 of 9 
 8.0 References  
 
Anonymous. 2012.  Eastern Filbert Blight Quarantine (Chapter 16 -474 WAC), Washington State  
Legislature. Last updated: 12/6/2012.  
Barss, H. P. 1930.  Eastern filbert  blight. California Department of Agriculture Bulletin 19:489 - 
490.  
Brown, K.  2014.  Oregon Bulletin (Supplements the 0214 O regon Administrative Rules  
Compilation). Volume 53, No. 6. State of Oregon. June 1, 2014.  
CABI. 2018 . Anisogramma anomala  (eastern filbert blight) . CAB International.  
https://www.cabi.org/isc/datasheet/16431  (accessed on  December 10, 2018 ). 
CFIA (Canadian Food Inspection Agency). 2015.  Risk of “New Virulent Strains” of Anisogramma  
anomala  to British Columbia Hazeln ut Industry – PRA 2014 -86. Plant Health Risk 
Assessment Unit.  
Davison, A. and Davidson, R. 1973.  Apioporthe  and Monochaetia  cankers reported in  Western 
Washington. Plant Disease Reporter.  
Gleason,  H. A. and Cronquist, A. 1991.  Manual of vascular plants of northeastern United States  
and adjacent Canada.  
Gottwald, T. and Cameron, H. 1980.  Disease increase and the dynamics  of spread of canker  
caused by Anisogramma anomala  in European filbert in the Pacific  Northwest. 
Phytopathology 70(11):  1087 -1092.  
IPPC. 2017.  International Standard for Phytosanitary Measures, ISPM No. 5, Glossary of  
phytosanitary terms , Food and Agricultural Organization of the United Nation, Rome, 
Italy.  
Johnson, K. B., Mehlenbacher, S. A., Stone, J.  K., Pscheidt, J. a nd Pinkerton, J. N. 1996.  Eastern  
filbert blight of European hazelnut. Plant Disease 80(12):1309.  Oregon State University 
Extension Service , Eastern Filbert Blight Help Page . 
Mehlenbacher, S. and Olsen, J. 1996.  The hazelnut industry in Oregon, USA.  Proc. IV  
International Symposium on Hazelnut 445.  
Molnar, T.  J., Goffreda, J.  C. and Funk, C. R. 2010. Survey of Corylus resistance to Anisogramma   
anomala from different geographic locations. HortScience. 45(5): 832 -836.  
Muehlbauer, M. 2017.  The use of  molecular and biochemical tools to assist in the breeding of 
hazelnuts ( Corylus spp.). Thesis – Doctor of Philosophy. Rutgers University. New 
Brunswick, New Jersey.  
Mue hlbauer, M., Capik, J.  M., Molnar , T. J. and Mehlenbacher, S.  A. 2018. Assessment of t he 
‘Gasaway’ source of resistance to eastern filbert blight in New Jersey. Scientia 
Horticulturae 235: 367.  
O’Dell, T. 201 8. Performance of New Hazelnut Cultivars in British Columbia – Final summary of  
hazelnut variety trial established in 2011 . Nature Tech Nursery Ltd. 
https://www.naturetechnursery.com/library -articles -and-other -info/  (accessed  
December 10, 2018 ).  
Pscheidt, J. W. , Pinkerton, J. and Johnson, K. B . 2017.  What is Your Risk from Eastern Filbert  
Blight? Oregon State University.  
http://oregonstate.edu/dept/botany/epp/EFB/risk.htm  (accessed on January 8, 2017).  
Sabaratnam, S. , Joshi, V. and Sweeney, M. 2009 . Plant Pathology Report. Abbotsford  Page 9 of 9 
 Agriculture Centre , BC Ministry of Agriculture and Lands. January, 2009.  
Thompson, M. A. 1930. Summary of State and Territorial plant Quarantines Affecting interstate  
Shipments. USDA Mis cellaneous Publication No. 80 (Revised April, 1933), Washington, 
D.C.