My rhubarb plant leaves are turning limp, & red to yellow. I pull out & discard these leaves. I loosened the soil with a pitchfork first. They have been fertilized with store-bought bagged compost placed around & not touching. Then mulched with straw. I water evenly when needed to keep them moist. I checked for any signs of rot. I found none. The same happened last season too. I will appreciate your expertise. Thanks in advance.
Linn County Oregon
Red leaves on rhubarb may be a sign of a bacterium, Erwinia rhapontici, also called Red leaf or Bacterial soft rot. It can cause decay in the crown of the plant. Can you send photos showing affected parts of the plant so we can confirm the identification? You can also read more here to see if this may be what is ailing your rhubarb: https://pnwhandbooks.org/plantdisease/host-disease/rhubarb-rheum-rhabarbarum-red-leaf
According to OSU Extension, red leaf might be spread in the soil or by insects that feed on plants, but the research is not conclusive about this.
The recommendations for dealing red lear on commercial rhubarb farms are to dig out and destroy affected plants, and not to replant rhubarb in the same area. This might not be welcome news to a home gardener. If your affected plant is still producing edible stalks you could maintain it for a while, then plant a new rhubarb in another location as far as possible from the affected plant and once it grows big, get rid of the original plant that is affected by red-leaf. Since insects might move the disease between plants there's still some risk to your new rhubarb, but if you are committed to trying to grow this much-loved pie ingredient, you might want to try.
Finally, you might want to check out these directions and make sure your "care and feeding" is optimal for this plant:
Grow Your Own Rhubarbhttps://catalog.extension.oregonstate.edu/ec797
I hope that is helpful and good luck with your gardening.