Red around my roobarb leaves
Could you tell me whot I can do to put it right pleas Margaret
Certified GKH Gardening Expert
Make sure that you have plenty of drainage holes in your container. This looks like a fungal infection which will be caused by the soil remaining too wet for too long. I would apply dolomitic lime and wettable sulfur to the top of the soil. This will kill off the infection, while conditioning the soil back to a more fertile condition for the plant.
Keep in mind that the old leaves may not recover completely, but the spread of the infection will stop.
This article will give you more information on the care of rhubarb: https://www.gardeningknowhow.com/edible/vegetables/rhubarb/grow-rhubarb.htm