Conservation Assessment for Butternut or White walnut (Juglans cinerea) L. USDA Forest Service, Eastern Region 2003 Jan Schultz Hiawatha National Forest Forest Plant Ecologist (906) 228-8491 This Conservation Assessment was prepared to compile the published and unpublished information on Juglans cinerea L. (butternut). This is an administrative review of existing information only and does not represent a management decision or direction by the U. S. Forest Service. Though the best scientific information available was gathered and reported in preparation of this document, then subsequently reviewed by subject experts, it is expected that new information will arise. In the spirit of continuous learning and adaptive management, if the reader has information that will assist in conserving the subject taxon, please contact the Eastern Region of the Forest Service Threatened and Endangered Species Program at 310 Wisconsin Avenue, Milwaukee, Wisconsin 53203. Conservation Assessment for Butternut or White walnut (Juglans cinerea) L. 2 Table Of Contents EXECUTIVE SUMMARY .....................................................................................5 INTRODUCTION / OBJECTIVES.......................................................................7 BIOLOGICAL AND GEOGRAPHICAL INFORMATION..............................8 Species Description and Life History..........................................................................................8 SPECIES CHARACTERISTICS...........................................................................9 ECOLOGY and HABITAT..................................................................................14 Understory Intolerance..............................................................................................................15 Range of Climatic Conditions...................................................................................................15 HABITAT...............................................................................................................16 New England.............................................................................................................................16 CONSERVATION STATUS ................................................................................17 POPULATION VIABILITY AND FRAGILITY...............................................19 Viability.....................................................................................................................................19 Fragility .....................................................................................................................................20 PRIMARY THREAT ............................................................................................20 Symptoms of Butternut Canker and Host Parasite Interactions................................................20 Host Range of the Pathogen......................................................................................................21 TRANSMISSION AND SPREAD OF BUTTERNUT CANKER.....................22 Wind and Rain Borne Transmission .........................................................................................22 Seed Borne Transmission..........................................................................................................22 Insect Transmission Possibilities ..............................................................................................22 Spread of Butternut Canker.......................................................................................................23 OTHER THREATS...............................................................................................24 CONTROL STRATEGIES FOR BUTTERNUT CANKER ............................24 Management Strategies .............................................................................................................24 Genotypes and Clonal Plantings ...............................................................................................25 Grafting of Butternut on Black Walnut.....................................................................................25 Silvicultural Practices................................................................................................................25 Hybrids and Species Resistance and Susceptibility ..................................................................26 Role of the Butternut Canker Pathogen and Host Species for the Development of Further Resistance to the Host ...............................................................................................................27 National and International Quarantine Regulations..................................................................27 STEWARDSHIP....................................................................................................28 Stewardship Needs ....................................................................................................................28 Re-establishment .......................................................................................................................28 Propagation methods for Juglans cinerea.................................................................................29 Conservation Efforts .................................................................................................................30 Tree Retention Guidelines (70-20-50 rule) ..............................................................................31 Guidelines for Selecting Potentially Resistant Trees ................................................................32 SUMMARY ............................................................................................................32 LITERATURE CITED .........................................................................................32 WEB SITES CITED..................................................................................................................40 OTHER RELATED REFERENCES ........................................................................................41 Conservation Assessment for Butternut or White walnut (Juglans cinerea) L. 3 OTHER RELATED WEB SITES.............................................................................................42 APPENDICES........................................................................................................43 APPENDIX A ...........................................................................................................................43 APPENDIX B: ..........................................................................................................................75 Forest Service Contacts:............................................................................................................75 Regional Forest Contacts ..........................................................................................................76 Other Contacts...........................................................................................................................76 Conservation Assessment for Butternut or White walnut (Juglans cinerea) L. 4 EXECUTIVE SUMMARY This Conservation Assessment provides available information regarding Juglans cinerea (butternut), its distribution, life history, habitat, ecology, and management practices. Juglans cinerea occurs throughout the central and eastern United States and southeastern Canada from New Brunswick to Minnesota, and south to Georgia and Arkansas (Gleason & Cronquist, 1991). Juglans cinerea tends to prefer moist, fertile soil and grows rapidly on well-drained soils on hillsides of mixed hardwood forests. At least 17 states within its range have more than 100 occurrences. As a result of butternut canker (Sirococcus clavigignati-juglandacearum), the species is susceptible to high mortality and high rates of infection (NatureServe, 2002). Between the years 1980 to 1994, there was a dramatic decrease in the number of live butternut trees throughout the United States. In many instances populations were down over 75 percent (Ostry et al., 1994). There is no known cure for this fungal disease (canker) and it may eliminate the species (Katovich et al., 1998). ACKNOWLEDGEMENTS Outside Reviewers We would like to thank our academic reviewers and agency reviewers outside of the United States Forest Service for their helpful comments on this manuscript. V.M.G. Nair, Professor of Plant and Forest Pathology, University of Wisconsin-Green Bay. Sylvia Taylor, Adjunct Associate Professor, Natural Resources, University of Michigan, Ann Arbor, Michigan. J. E. Juntz, Professor of Plant Pathology, University of Wisonsin-Madison. National Forest Reviewers We also thank our internal National Forest reviewers for their suggestions and corrections and for providing us with element occurrences for their National Forests. Michael E. Ostry, Research Plant Pathologist, North Central Research Station, St. Paul, MN. Steven Katovich, Forest Entomologist, Northeastern Area National Forests, State and Private Forestry, St. Paul, Minnesota. Manfred Mielke, Forest Health Monitoring, North Central Research Station, St. Paul, MN. We appreciate the reviews of each National Forest botanist and ecologist, but we are especially grateful to Ian Shackleford (Ottawa) for his especially detailed review. See Contact section at end of report for complete list of Forest Botanists/Reviewers. Herbarium and Heritage Data We appreciate the sharing of occurrence information for this species