The 2024 Tennessee Chapter Pollination Workshop was held on June 8 to great success, bringing together 22 enthusiastic volunteers for a day of hands-on learning at the Tennessee Tech Orchard. Established in 2005 using the direct seed planting method, the TTU backcross orchard includes a row of robust, blight resistant F1 hybrids, resulting from a 2004 cross between a naturally occurring Clay County, TN American chestnut, and the Chinese cultivar ‘Gideon.’ These F1s (originally planted as controls in the 2005 backcross orchard), in addition to their blight resistance, exhibit promising resistance to Phytophthora cinnamomi (causal agent of the phytophthora root rot disease, PRR), which has been validated through progeny tests and PRR-screening (Perkins et al., 2019). They were chosen to be the female parents this year in crosses designed to move PRR resistance into the best selections of the southern TACF chapters.
Dr. Hill Craddock gives a lecture to the volunteers on the biology of Castanea species. Photographer: Greg Weaver
In addition to the genetic makeup of its trees, the TN-TTU-05 orchard was chosen for its accessibility and the ideal structure, which are tall, healthy F1s, spaced in a flat, open area. These orchard conditions make it easier to perform and teach pollination techniques. Beyond its practicality, the orchard’s location near I-40, a major interstate highway, allowed volunteers from across the state to participate.
Volunteer Faith J. up on the ladder to bag the female flowers of the chestnut tree. Photographer: Tom Haxby
During the 2024 workshop, participants heard a short lecture from Dr. Craddock on the pollination biology of Castanea species and saw an active demonstration of emasculation and bagging of chestnut flowers. They learned about the importance of proper labelling and the labelling conventions of the TACF chapter breeders. They were then engaged directly in hand the pollination techniques used to create hybrid chestnut trees using pollen provided by colleagues in the Georgia, Carolinas, and Alabama chapters ladders and bucket lifts to access the crowns of the trees, successfully performing hundreds of pollinations.
Dr. Hill Craddock shows the anatomy of a female flower to a group of volunteers. Photographer: Tom Haxby
The workshop’s outcome was exceptional. The volunteers completed 27 distinct crosses. Fruit set was excellent despite the late summer drought. The burs were harvested in September yielding 2,553 hand pollinated seeds! These efforts advance the TACF breeding program’s goal of stacking resistance to both Phytophthora cinnamomi and Cryphonectria parasitica, ensuring future generations of resilient chestnut trees well adapted to conditions here in the South. Volunteers left with hands-on experience, new knowledge, and a sense of accomplishment, with many eager to apply their skills in their own orchards.
Volunteer group photo after successful pollination workshop at Tennessee Tech Orchard. Photo Katheryn Telles
Perkins, M.T., Robinson, A.C., Cipollini, M, and Craddock, J.H.. (2019) Identifying host resistance to Phytophthora cinnamomi in hybrid progeny of Castanea dentata and Castanea mollissima. HortScience 54(2): 221-225. https://doi.org/10.21273/HORTSCI13657-18
