The link below suggests that you do cover the stalks to prevent crown rot. It is mentioned in the 4th paragraph.

Hope this helps
Ian

Here is a link that might be useful: Tuber harvest

Thank you very much for this excellent article ians_gardener! I have learned so much from this message board! I have decided to dig up all of my dahlias. I have used the saran wrap method and am very impressed with it.

Glad to hear that the Saran method worked for you Mingus Alex. It is a space saver for sure.

I read another interesting approach to blocking rain from rotting tuber clumps once the stalks are cut: squirt in some expandable foam that they use to fill gaps in housing construction around doors and window frames. Doesn't hurt the plants, fills the available space and prevents water from entering.

I am digging the clumps that survived our astronomical rainfall the past few days: they had no such protection, and only two have seemed bothered or slightly rotted. Those two were severe leaners who fell over several times during the growing season, and their stalks may have been weakened or cracked somehow. The clumps fell apart upon digging, which is odd here.