Scientists & Staff
Biological and Environmental Influences on Forest Health and Productivity
Research Plant Pathologist
1561 Lindig Ave.
St. Paul, MN 55108
As a Research Plant Pathologist, I conduct studies on invasive tree pathogens and associated insects. These studies are often conducted in collaboration with scientists, forest health specialists, and foresters in federal, state and county agencies as well as universities. Practical guidelines ranging from preventing introduction of invasive pathogens to managing or mitigating diseases caused by established pathogens are the outcomes of these studies. I also collaborate with US Forest Service Northeastern Area State and Private Forestry and state agencies in detection and monitoring activities for emerging diseases. My current research efforts concern:
- Hickory decline and dieback research
- Determine frequencies of decline/dieback and mortality of smooth bark hickories in appropriate forest cover types where deviations from expected levels of mortality have been observed (Indiana, Iowa, Minnesota, Ohio, New York, and Wisconsin).
- Quantify relationships between decline/dieback incidence and a) pathogen and/or insect pest presence, and b) prior land use, fire history, soils and drought.
- Determine the role of two newly described Ceratocystis species in decline/dieback and mortality of bitternut hickory.
- Oak wilt research
- Investigate temporal and spatial aspects of belowground transmission of C. fagacearum in relation to current disease management strategies. These studies include evaluation of the efficacy of propiconazole and of mechanical root graft disruption in operational, oak wilt control programs.
- Thousand Cankers Disease (TCD)
- Collaborate with state agencies on visual surveys for the disease in Iowa, Minnesota and Missouri
- Evaluate trap tree method for early detection of walnut twig beetle in eastern black walnut in Tennessee and incorporate the method in Indiana and Missouri surveys for TCD
- Investigate other bark and ambrosia beetles known to attack eastern black walnut for their potential association with the TCD pathogen, Geosmithia morbida
I would like to develop two areas of interest into research projects in the near future:
- Molecular probes for detection of selected pathogens on associated insects.
- Describe the major biotic and abiotic factors negatively impacting the health of Colorado blue spruce and of white spruce in Midwestern, urban landscapes.
Why This Research is Important
Oak-hickory forests comprise 29% of the 31 million hectares of forest land in the Upper Midwest (IL, IN, IA, MI, MN, MO and WI). The oak species group is the most important aggregation of hardwoods in the United States. Oak decline and oak wilt are responsible for much of the observed oak deterioration and mortality in the midwestern forests. In addition, new exotic pathogens, such as Phytophthora ramorum (cause of Sudden Oak Death) and Raffaelea quercivora (cause of Japanese oak wilt), are potential threats to the health of oaks in these forests. Our oak disease research addresses both the need for early detection of any unintentionally introduced exotic pathogens and for new or refined management tools for well-established pathogens, such as Ceratocystis fagacearum (cause of oak wilt in the USA).
Hickories are an important component of many forest associations in the eastern United States, particularly various oak-hickory cover types. Sites impacted by hickory decline or dieback and mortality have recently been reported to lose a high proportion of smooth bark hickories, particularly bitternut, over a very short period of time (3 to 5 years). These losses cause a significant, adverse impact to wildlife, timber value and biodiversity in affected stands. Our goal is to identify significant biotic and abiotic contributors to the decline or dieback and develop site or silvicultural guidelines for mitigating the tree losses and stand impacts associated with this problem.
Eastern black walnut (Juglans nigra) is the most economically important hardwood species in the eastern USA. Lumber from this species has a high market price and exports from the USA exceed $ 40 million annually. The species is also important for nut production, wildlife habitat, riparian buffers, windbreaks and other ecosystem services. Thousand cankers disease, caused by an interaction of the walnut twig beetle (Pityophthorus juglandis) and a fungus (Geosmithia morbida), is a threat to the health of eastern black walnut.
- University of Minnesota, Ph.D. Plant Pathology, 1983
- Colorado State University, M.Sc. Plant Pathology, 1978
- Fairmont State College, B.Sc. Biology, 1976
- American Phytopathological Society
- International Society of Arboriculture
- Minnesota Society of Arboriculture
- Northeastern Nursery Association
- Minnesota Shade Tree Advisory Committee
Featured Publications & Products
- Van Sambeek, Jerry; Juzwik, Jenny. 2010. What's killing my walnuts -- how to find help.
- Blaedow, Ryan A.; Juzwik, Jennifer. 2010. Spatial and temporal distribution of Ceratocystis fagacearum in roots and root grafts of oak wilt affected red oaks.
- Blaedow, Ryan A.; Juzwik, Jennifer; Barber, Brian. 2010. Propiconazole distribution and effects on Ceratocystis fagacearum survival in roots of treated red oaks.
- Juzwik, Jennifer; O'Brien, Joseph; Evenson, Charles; Castillo, Paul; Mahal, Graham. 2010. Controlling spread of the oak wilt pathogen (Ceratocystis fagacearum) in a Minnesota urban forest park reserve.
- Park, J.-H.; Juzwik, J.; Haugen, L.M. 2010. Ceratocystis Canker of Bitternut Hickory Caused by Ceratocystis smalleyi in the North-Central and Northeastern United States.
Publications & Products
- Park, J.-H.; Juzwik, J. 2014. Ceratocystis smalleyi colonization of bitternut hickkory and host responses in the xylem.
- Ginzel, Matthew; Juzwik, Jennifer. 2014. Geosmithia morbida, the causal agent of thousand cankers disease, found in Indiana.
- Reed, Sharon; English, James; Juzwik, Jennifer; Ginzel, Matt. 2013. Bark and ambrosia beetles and their associated fungi colonizing stressed walnut in Missouri and Indiana.
- Juzwik, Jennifer; Park, Hi-Hyun; Banik, Mark T.; Haugen, Linda. 2013. Biotic agents responsible for rapid crown decline and mortality of hickory in northeastern and north central USA.
- Park, J.-H.; Juzwik, J.; Cavender-Bares, J. 2013. Multiple Ceratocystis smalleyi infections associated with reduced stem water transport in bitternut hickory.
- Park, J.-H.; Juzwik, J. 2012. Fusarium canker of bitternut hickory caused by Fusarium solani in the North-Central and Northeastern United States.
- Juzwik, Jennifer; Park, Ji-Hyun. 2011. Additional pest surveyed: hickory decline.
- Juzwik, Jennifer; Appel, David N.; MacDonald, William L.; Burks, Susan. 2011. Challenges and successes in managing oak wilt in the United States.
- Ostry, M.E.; Venette, R.C.; Juzwik, J. 2011. Decline as a disease category: Is it helpful?.
- Juzwik, Jennifer; Park, Ji-Huyn; Haugen, Linda. 2010. Hickory decline and mortality: Update on hickory decline research.
- Juzwik, Jennifer; Haugen, Linda; Park, Ji-Hyun; Moore, Melanie. 2008. Fungi associated with stem cankers and coincidental scolytid beetles on declining hickory in the upper midwest.
- Juzwik, Jennifer. 2008. Methyl isothiocyanate and chloropicrin concentrations in bareroot forest nursery soils and above soil surface treatments following fumigation.
- Juzwik, Jennifer; Harrington, Thomas C.; MacDonald, William L.; Appel, David N. 2008. The origin of Ceratocystis fagacearum, the oak wilt fungus.
- Hayslett, Maya; Juzwik, Jennifer; Moltzan, Bruce. 2008. Three Colopterus beetle species carry the oak wilt fungus to fresh wounds on red oak in Missouri.
- Kromroy, Kathryn W.; Juzwik, Jennifer; Castillo, Paul; Hansen, Mark H. 2008. Using Forest Service forest inventory and analysis data to estimate regional oak decline and oak mortality.
- Downing, Marla c.; Thomas, Vernon L.; Juzwik, Jennifer; Appel, David N.; Reich, Robin M.; Camilli, Kim. 2008. Using classification tree analysis to predict oak wilt distribution in Minnesota and Texas.
- Schwingle, B.W.; Juzwik, J.; Eggers, J.; Moltzan, B. 2007. Phytophthora species in soils associated with declining and nondeclining oaks in Missouri forests.
- Ward, Kathleen; Kromroy, Kathryn; Juzwik, Jennifer. 2007. Transformation of the oak forest spatial structure in the Minneapolis/St. Paul metropolitan area, Minnesota, USA over 7 years.
- Seeland, T.M.; Ostry, M.E.; Venette, R.; Juzwik, J. 2006. An annotated bibliography of invasive tree pathogens Sirococcus clavigignenti-juglandacearum, Phytophthora alni, and Phytophthora quercina and a regulatory policy and management practices for invasive species.
- Ambourn, Angie K.; Juzwik, Jennifer; Eggers, Jordan E. 2006. Flight periodicities, phoresy rates, and levels of Pseudopityophthorus minutissimus branch colonization in oak wilt centers.
- Wang, Dong; Fraedrich, Stephen W.; Juzwik, Jennifer; Spokas, Kurt; Zhang, Yi; Koskinen, William C. 2006. Fumigant distribution in forest nursery soil under water seal and plastic film after application of dazomet, metam-sodium and chloropicrin.
- Wang, Dong; Fraedrich, Stephen W.; Juzwik, Jennifer; Spokas, Kurt; Zhang, Yi; Koskinen, William C. 2006. Fumigant distribution in forest nursery soils.
- Kromroy, Kathryn; Ward, Kathleen; Castillo, Paul; Juzwik, Jennifer. 2006. Relationships between urbanization and the oak resource of the Minneapolis/St. Paul metropolitan area from 1991 to 1998.
- Wang, D.; Juzwik, J.; Fraedrich, S.W.; Spokas, K.; Zhang, Y.; Koskinen, W.C. 2005. Atmospheric emissions of methyl isothiocyanate and chloropicrin following soil fumigation and surface containment treatment in bare-root forest nurseries.
- Ward, Kathleen; Juzwik, Jennifer. 2005. Change in the Minneapolis/St. Paul Metropolitan Area Oak Forests from 1991 to 1998.
- Wang, Dong; Juzwik, Jennifer; Fraedrich, Stephen. 2005. Emission and soil distribution of fumigants in forest tree nurseries.
- Eggers, Jordan; Juzwik, Jennifer; Bernick, Shawn; Mordaunt, Lori. 2005. Evaluation of propiconazole operational treatments of oaks for oak wilt control.
- Ambourn, Angie K.; Juzwik, Jennifer; Moon, Roger D. 2005. Seasonal dispersal of the oak wilt fungus by Colopterus truncatus and Carpophilus sayi in Minnesota.
- Ward, K.; Juzwik, J.; Bernick, S. 2004. Efficacy of Alamo for prophylactic and therapeutic treatment of oak wilt in red oaks, 2004.
- Scarbrough, Dwight; Juzwik, Jennifer. 2004. Native and exotic insects and diseases in forest ecosystems in the Hoosier-Shawnee ecological assessment area.
- Juzwik, J.; Cook, S.; Haugen, L.; Elwell, J. 2004. Oak Wilt: People and Trees, A Community Approach to Management.
- Juzwik, Jennifer; Skalbeck, Thomas C.; Newman, Marc F. 2004. Sap beetle species (Coleoptera: Nitidulidae) visiting fresh wounds on healthy oaks during spring in Minnesota.
- Cohen, S.D.; Juzwik, J., eds. 2003. Sudden oak death online symposium.
- Kromroy, Kathryn W.; Juzwik, Jennifer; Castillo, Paul D. 2003. Use of USDA forest inventory and analysis data to assess oak tree health in Minnesota.
- Ocamb, C. M.; Juzwik, J.; Martin, F. B. 2002. Fusarium spp. and Pinus strobus seedlings: root disease pathogens and taxa associated with seed.
- Juzwik, Jennifer; Kromroy, Kathryn; Allmaras, Raymond. 2002. Comparison of Tillage for Improving Soil Conditions and Root Health in Barefoot Nurseries.
- Juzwik, Jennifer; Kromroy, Kathryn; Allmaras, Raymond. 2002. Comparison of tillage equipment for improving soil conditions and root health in bareroot nurseries.
- Kyhl, John F.; Bartelt, Robert J.; Cosse, Allard; Juzwik, Jennifer; Seybold, Steven J. 2002. Semiochemical-mediated flight responses of sap beetle vectors of oak wilt, Ceratocystis fagacearum.
- Cervenka, Valerie J.; Skalbeck, Thomas C.; Kyhl, John F.; Blackford, Darren C.; Juzwik, Jennifer J.; Seybold, Steven J. 2001. How to identify common nitidulid beetles associated with oak wilt mats in Minnesota.
- Cease, Kory R.; Juzwik, Jennifer. 2001. Predominant nitidulid species (Coleoptera: Nitidulidae) associated with spring oak wilt mats in Minnesota.
- Juzwik, Jennifer. 2000. An oak wilt primer.
- Juzwik, Jennifer; Schmidt, Thomas L. 2000. Oak wilt and oak decline in the upper midwest USA.
- Juzwik, J; Gust, K. M.; Allmaras, R. R. 1999. Influence of cultural practices on edaphic factors related to root disease in Pinus nursery seedlings.
- Juzwik, Jennifer; Johnson, Gary. 1999. Oak Wilt in Minnesota: It's Still Here and We're Doing Something About It!.
- Juzwik, Jennifer. 1999. Overland transmission of Ceratocystis fagacearum: extending our understanding.
- Burnes, Todd A.; Juzwik, Jennifer; Blanchette, Robert A. 1999. Screening Pinus sylvestris grown for the production of Christmas trees for resistance to western gall rust Peridermium harknessii using different sources of aeciospores.
- Juzwik, Jennifer; Cease, Kory R.; Meyer, Jason M. 1998. Acquisition of Ophiostoma quercus and Ceratocystis fagacearum by nitidulids from O. quercus-colonized oak wilt mats.
- Juzwik, Jennifer; Meyer, Jason M. 1997. Colonization of oak wilt fungal mats by Ophiostoma piceae during spring in Minnesota.
- Juzwik, J.; Stenlund, D. L.; Allmaras, R.R.; Copeland, S. M.; McRoberts, R. E. 1997. Incorporation of tracers and dazomet by rotary tillers and a spading machine.
- Schmidt, Elmer L.; Juzwik, Jennifer; Schneider, Brian. 1997. Sulfuryl fluoride fumigation of red oak logs eradicates the oak wilt fungus.
- Seybold, Steven; Juzwik, Jennifer. 1996. HOW to Identify Common Nitulid Beetles Associated with Oak Wilt Mats in Minnesota.
- Juzwik, J.; Rugg, D. J. 1996. Seedling mortality and development of root rot in white pine seedlings in two bare-root nurseries.
- Ocamb, Cynthia M.; Juzwik, Jennifer. 1995. Fusarium species associated with rhizosphere soil and diseased roots of eastern white pine seedlings and associated nursery soil.
- Juzwik, Jennifer. 1993. Morphology, cultural characteristics, and pathogenicity of Rhizosphaera kalkhoffii on Picea spp. in northern Minnesota and Wisconsin.
- Juzwik, Jennifer; O Brien, Joseph G. 1990. Premature Needle Loss of Spruce.
National Research Highlights
|Eastern Black Walnut Trees Plagued by More Than Thousand Cankers Disease|
Thousand cankers disease, caused by the interaction of the walnut twig beetle and the fungus Geosmithia morbida, has been detected in four easte ...