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Individual Highlight

DNA-based Method Enhances Detection of the Oak Wilt Fungus

Photo of City forester collecting branch sample from actively wilting white oak tree. USDA Forest ServiceCity forester collecting branch sample from actively wilting white oak tree. USDA Forest ServiceSnapshot : Oak wilt is a major cause of tree death in the eastern United States. Symptoms are slower to develop in white oaks species than red oaks and oak wilt in all species may be confused with damage caused by other organisms. A Forest Service scientist and her research partners tested a commercial DNA-based detection method for use by plant diagnostic laboratories. They found that it greatly enhanced the ability to diagnose the fungus in oak wilt-affected trees.

Principal Investigators(s) :
Juzwik, Jennifer 
Research Location : Multiple suburbs of the greater Minneapolis-St. Paul metropolitan area
Research Station : Northern Research Station (NRS)
Year : 2015
Highlight ID : 862

Summary

Oak wilt is an important disease of oaks in the eastern United States. Early and accurate diagnosis of this fungal disease is important for all who wish to control it. A Forest Service scientist, in collaboration with research partners at the University of Minnesota, compared the use of a DNA-based method to the standard isolation method that is used in plant disease diagnostic laboratories. DNA was extracted from sapwood of actively wilting or dead red, bur and white oaks using a commercially available kit. The DNA-based method was superior to the isolation method in detecting the fungus in wilting branches of bur and white oak trees, and similar to isolation for wilting red oaks. The fungus could not be detected in dead branches of bur and white oaks using isolation, but was found in at least one dead branch of each of the same trees using DNA. The fungus was detected in sapwood “scars” left by deteriorated fungus mats in dead red oaks using the molecular method, but not by isolation. The DNA-based method greatly enhances the ability of diagnostic laboratories to detect the oak wilt fungus under a wider range of conditions compared to standard isolation.

Forest Service Partners

External Partners

  • Joseph O'Brien, Northeastern Area State and Private Forestry
  • Anna Yang, formerly Graduate Research Assistant, Department of Plant Pathology, University of Minnesota, St. Paul
  • City foresters from several communities in the Minneapolis-St. Paul metropolitan area

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