2005 Pollinations

October 12, 2005

During the spring and early summer of 2005, Dr. Paul H. Sisco, Regional Science Coordinator of The American Chestnut Foundation’s Southern Appalachian Regional Office, directed the back-cross breeding of four year old, 100% American chestnut trees. He used pollen from hybrid American/Chinese chestnut trees that grow in the American Chestnut Foundation’s Meadowview Research Farms located in Virginia. The 100% American chestnut trees that were hand pollinated grow in a Mother Tree Orchard at Fletcher Station which is located near Asheville, NC.

Pollination Process

  • The first step in hand pollinating American chestnut trees is to protect the immature female flower stalk (shown between the person’s index finger and thumb)from inadvertently being pollinated by other nearby chestnut trees. Male catkins growing on the same limb are removed to isolate the female flower stalk.
  • A white paper bag is carefully placed over the limb on which the female flower stalk grows. The bag is secured with a large wire paper clip.
  • The white paper bag is removed to expose the female flower stalk when it is time to hand pollinate the mature female flowers of the 100% American chestnut tree, pollen supplied from a known source is used.
  • After the hand pollination is completed, a brown paper sack is carefully placed over the female flower stalk to prevent pollen from nearby trees from affecting the results of the hand pollination effort. A brown paper sack is used to distinguish pollinated female flower stalks from the unpollinated stalks previously bagged. ┬áThe brown paper bag is labeled prior to its being placed over the female flower stalk to identify when the pollination occurred and what the source was for the pollen.
  • The nuts produced will be a back-crossed variety of chestnut (a 100% American chestnut back-crossed with pollen from a hybrid American/Chinese parent) that will be grown and, after three to four years, inoculated with Chestnut bark fungus to determine the tree’s resistance to Chestnut blight. Survivors will be checked for strong American Chestnut tree characteristics. Trees that pass the tests will be used for further back-cross and inter-cross breeding to eventually produce hybrid chestnut trees that are 94% American and 6% Chinese and which demonstrate good blight resistance characteristics. The selected trees will be used to produce nuts for propagation of blight resistant, 94% American/6% Chinese chestnut trees that eventually will be set out into the Eastern forests of America.