2017 Faculty Update: Jennifer Juzwik
The forest and shade tree pathology laboratory group (see Figure) led by Jennifer Juzwik (Adjunct Associate Professor) and working out of the St. Paul Annex of the Northern Research Station, U.S. Forest Service, has both ongoing and exciting new research and development activities to report on this year. Most of the projects are collaborative efforts with colleagues “near and far.” The lab group’s work can be classified under four topic areas: diagnostics and early detection of oak wilt, etiology of emerging diseases, phytosanitary treatments of hardwood logs for export, and management of important tree diseases. Juzwik, Dr. Brett Arenz and Alex Feltmeyer (M.S. student) are collaborators on a 2015 Minnesota Invasive Terrestrial Plant and Pest Center (MITPPC) funded project led by Dr. Abdennour Abbas (Bioproducts and Biosystems Engineering Dept.) to develop a rapid and accurate diagnostic tool using for nanoaggregation-enhanced chemiluminescence for detecting the oak wilt fungus in sapwood of oak trees. Also working in Juzwik’s lab is Anna Yang, U of MN Researcher (Deptartment of Forest Resources), where she is collaborating with staff from Dr. Jeannine Cavender-Bares’ (Dept. of Ecology, Evolution and Behavior) lab to determine whether hyperspectral sensors can detect pre-visual symptoms of oak wilt in red and bur oak seedlings. This exploratory greenhouse study is funded by a Grand Challenges Research Grant received by Cavender-Bares, Dr. Rebecca Montgomery (Dept. of Forest Resources) and Juzwik. Field studies on the etiology of thousand cankers disease of walnut in the eastern USA have been underway since 2014. Evaluation of Juglans nigra branches on mature trees in Indiana and Ohio that were inoculated with several known (including Geosmithia morbida) or putative canker pathogens in 2015 is underway in cooperation with colleagues at Purdue University. Melanie Moore (US Forest Service Biological Technician) and Margaret McDermott-Kubeczko (PLPA Researcher) were key players in setting up these field experiments and recently completed the evaluation of June 2015 inoculations. In the absence of the walnut twig beetle, G. morbida was found to cause very small, annual cankers on the branches and were similar to those caused by Fusarium solani in Ohio, but did not differ in size from necrosis associated with water controls in Indiana. In addition, Moore has detected G. morbida on an increasing number of scolytine species other than the walnut twig beetle (e.g. weevils, ambrosia beetles) collected in states with and without TCD. Moore is also documenting the mycobiota of the walnut twig beetle collected in its native range (New Mexico) in collaboration with Dr. Peter Kennedy (College of Biological Sciences). In April, Juzwik started working with colleagues on Hawaii Island (USDA-ARS and University of Hawaii-Manoa) to describe the two diseases that contribute to rapid ohia death, a significant and emerging disease currently only known to occur on that island. Kat Sweeney, PlPA Ph.D. student, will use microscopic imaging and histochemical techniques to elucidate patterns of Ceratocystis species colonization in ohia wood and characterize host response. Yang has been leading the biological evaluation efforts for two phytosanitary treatment of log projects: sulfuryl fluoride fumigation funded by USDA NIFA grant and vacuum steam treatment funded by USDA APHIS for the eradication of viable Ceratocystis fagacearum in colonized logs. Collaborators for these projects include colleagues from USDA APHIS PPQ Otis Lab, Virginia Tech, and the University of Tennessee. Lastly, refinement of guidelines for management of oak wilt are the focus of current field research on oak wilt. Evaluation and documentation of the efficacy of double vibratory plow lines at the primary line placement site for stopping the below-ground spread of C. fagacearum began this summer with funding from MITPPC awarded to Cavender-Bares, Montgomery and Juzwik. Paul Castillo (US Forest Service Forester) is assisting U of MN summer interns in site selection and data collection. Juzwik and two Arborjet colleagues are currently completing a comparative study of two injection techniques for systemic fungicide treatment of oak wilt. Feltmeyer will evaluate wound closure response of treated trees as a follow-up to this project.