Chop and drop. I've written before about the virtues of making 'Comfey tea' to use as a fertiliser. That stinky brew is made by steeping the leaves of Comfrey in water for several weeks. [see entry dated 26th. August 2022] 

 An even simpler approach is to cut the leaves off and use them as a mulch, best done at a damp time of year so they break down quickly. There are several clumps on the Rhubarb batch; I gave them the chop and let them drop right there.

 The thinking is that Comfrey is a 'dynamic accumulator' of NPK- nitrogen, phosphorus, potassium. All Symphytum species can be used to for this purpose but S. x uplandicum - sometimes called Russian Comfrey- is the leafiest. Conveniently there is plenty of it growing on and around the allotment.