Inoculation of the Paul Vonk Orchard, Macon County, NC

June 9, 2009

Dr. Paul Sisco led the effort to inoculate the back-cross chestnut orchard Paul Vonk maintains in Macon County, NC, near the town of Scaly. Paul was assisted by interns, Alisha Goodman and Margot Wallson, and by Paul Vonk and Russell Regnery. The effects of the inoculations on the trees in the orchard will be rated in the near future to determine the degree of resistance individual trees have to chestnut bark blight. After evaluating the ratings, the trees displaying the best resistance, as well as good American chestnut tree characteristics, will be saved for further pollinations that should produce nuts from which trees with strong blight resistance characteristics will be grown.

The orchard is located in Macon County near Scaly, NC. It was inoculated on June 9, 2009 with two strains of chestnut bark blight (Cryphonectria parasitica, one very agressive and one much weaker) to test resistance of individual trees in the orchard to the fungus. As controls, pure American chestnut trees, which should have no resistance to the inoculated bark blight, and Chinese chestnut trees, which should display strong blight resistance, are included in the orchard and will be inoculated as well. (Click on any picture to enlarge it.)

Inoculation Process:

  • The areas on the trees that are to be inoculated are first cleaned with a sterile cloth soaked in a 70% ethanol solution. Two holes are bored with a Number 2 cork borer in the cleaned area near the base of the tree and two places higher on the truck of the tree.
  • Meadowview Farms, the American Chestnut Foundation’s research farm, supplies two strains of chestnut bark blight fungus (one aggressive and one weak) grown in petri dishes on potato agar.
  • Number 2 cork borer are used to remove a plug of the agar on which the more virulent strain of fungus has been grown. She places a plug in each of the two holes previously bored in the bark near the base of the tree.
  • Plugs of agar, on which the less virulent strain of fungus has been grown, are placedĀ  in two spots previously bored in the bark higher on the trunk.
  • Tape is wrapped around the tree trunk at each spot of inoculation to secure the plugs and to ensure they take effect.
  • The resistance that individual trees display to the blight will be rated to determine which trees in the orchard to save for further breeding to produce trees that have good blight resistance and good American chestnut tree characteristics.