Vernonia lettermannii presented a conditioning challenge in the threshing stage. Threshing is the process by which the seed is mechanically separated from its plant parts, in this case a shell and coma. After multiple failed attempts to separate comas from seed, we found the most effective to be gently rubbing with a sponge against an elongated slotted screen. This produced shells, seeds, and a kind of wool (derived from the comas).
Once separated, the seed could easily become trapped within the 'Ironwool' material, becoming nearly impossible to separate. For this reason, special care was taken during conditioning to minimize contact between both substances.
- Thresh collected seed by rubbing with sponge against screen.
- Use pressurized air nozzle to separate threshed debris from seed by blowing the material through a series of decreasing size screens.
- Separate poorly filled seed from heavier seed using South Dakota Air Blower.
Many thanks to Alan Gaul for his help in the conditioning process.