If you suspect that your rhubarb plant may be suffering from illness, here are some signs that you can look for.
Change in Leaf Color
One of the most obvious changes to rhubarb plants when disease is present is a change in the color of the leaves. If your plant has leaves turning red, this could be a sign of leaf disease. This disease usually goes after the crown and root areas of your plant. Eventually the entire plant will turn red and shrivel. Instead of changing color completely, leaves can also develop spots on them that are of a different color. Yellow spots on leaves is normally the result of a bacterial infection and should be dealt with at once.
The leaves can also develop sheens on top of them that can be a problem. Depending on the condition, rhubarb plants can develop rust sheens on the leaves or even mildew.
Serious illnesses with rhubarb can destroy the plant from the inside. A rot in the root is an example, but you can catch it before it becomes critical by paying close attention to plants that start to sag. If there is a sudden weakness in the body of the plant for no apparent reason, it could signify a diseased plant.