Oak Wilt

Research Issue

Oak wilt, caused by the exotic fungus, Ceratocystis fagacearum, is one of the most serious diseases of oaks (Quercus) in the Midwest and kills tens to hundreds of thousands of oak trees every year.  Infection by the fungus causes clogging of water conducting vessels, leading to wilt and death of infected trees.  Red oaks are more susceptible than white oaks and can die within several to many weeks.  Spread of the causal fungus from diseased to healthy trees occurs both above and below-ground.  New infection centers are created when certain species of sap beetles pick up fungal spores from infected trees and carry them to healthy trees.  If these beetles land on fresh wounds (e.g. such as those resulting from storms or tree pruning), the tree will likely become infected.  Below-ground spread occurs when the fungus is carried through the water conducting system from diseased trees to healthy ones through grafted roots.

 Our Research

Our research ranges from specific studies on basic questions concerning insects involved in overland spread of oak wilt to integrating our scientific and experiential knowledge in management guidelines developed by state land management agencies.  Some examples of our research are:
1) determination of the principal insect vector species involved in overland transmission of the oak wilt fungus in the Central United States,
2) use of the systemic fungicide propiconazole to prevent root graft spread of the causal fungus in red oaks,
3) determination of the success rate of mechanical root graft disruption (using vibratory plow) to stop spread of oak wilt in operational disease control programs and comparison of models for locating the root graft disruption lines, and
4) contribution of scientific expertise to the development of statewide guidelines (Wisconsin) to minimize oak wilt threat during timber harvesting activities. 

Expected Outcomes

Our goal is to provide natural resource managers of state, county and urban forests with new or improved tools for integrated management of oak wilt.

Research Results 

Juzwik, J.; Harrington, T.C.; MacDonald, W.L.; Appel, D.N. 2008. Ann. Rev. Phytopathol. (in press). The origin of Ceratocystis fagacearum, the oak wilt fungus.

Hayslett, M., Juzwik, J., and Moltzan, B. 2008. Three Colopterus beetle species carry the oak wilt fungus to fresh wounds on red oaks in Missouri. Plant Disease 92:270-275. 

Juzwik, J.; Cummings-Carlson, J.; Scanlon, K. 2008. USDA FS, SRS.  Risk analysis and guidelines for harvest activities in Wisconsin oak timberlands to minimize oak wilt threat.

Ambourn, A.K., Juzwik, J., and Eggers, J. 2006. Flight periodicities, phoresy rates, and colonization characteristics of Pseudopityophthorus minutissimus in oak wilt centers. Forest Science 52:243-250.

Ambourn, A., Juzwik, J.,  and Moon, R.D. 2005. Seasonal dispersal of the oak wilt fungus by Colopterus truncatus and Carpophilus sayi in Minnesota. Plant Dis. 89:1067-1076.

Eggers, J., Juzwik, J., Bernick, S., and Mordaunt, L. 2005. Evaluation of propiconazole operational treatments of oaks for oak wilt control. Res. Note NC-390, North Central Res. Sta., US Dept. of Agric., For. Serv., St. Paul, MN.

Juzwik, J.; Cook, S.; Haugen, L.; Elwell, J. 2004. GTR-NC-240. Oak wilt: people and trees, a community approach to management. Version 1.3.

Juzwik, J., Skalbeck, T.C., and Neuman, M.F. 2004. Sap beetle species (Coleoptera: Nitidulidae) visiting fresh wounds on healthy oaks during spring in Minnesota. For. Sci. 50: 757-764.

Research Participants

Principal Investigators

• Jennifer Juzwik, US Forest Service - Northern Research Station, Research Plant Pathologist

Research Partners

• A. Ambourn, formerly Graduate Research Assistant, Dept. of Entomology, Univ. of Minnesota
• M. Hayslett, formerly Graduate Research Assistant, Dept. of Plant Pathology, Univ. of Minnesota
• R. Blaedow, Ph.D. candidate, Dept. of Plant Pathology, Univ. of Minnesota
• J. O’Brien, NA State and Private Forestry, US Forest Service, St. Paul, MN
• S. Bernick, Rainbow Treecare Scientific Advancements, Minneapolis, MN
• C. Evenson, Three Rivers Park District, Plymouth, MN
• J. Cummings-Carlson, Wisconsin Dept. Natural Resources, Fitchburg, WI
• K. Scanlon, Wisconsin Dept. Natural Resources, Fitchburg, WI

For further details log on website :
https://www.nrs.fs.fed.us/disturbance/invasive_species/oak_wilt/