Why Are the Leaves on My Rhubarb Plants Turning Bright Red?

Rhubarb leaves should be a consistent green.

Rhubarb leaves should be a consistent green.

Rhubarb (Rheum rhabarbarum, hardy in U.S. Department of Agriculture plant hardiness zones 3 to 8) is known for its bright red stalks that become mellow and sweet tasting when cooked in pies and jams. This perennial plant is usually simple to grow, but it can develop problems that require fast action. Among these are two diseases, both known as red leaf. One is a leaf spot disease and the other is a type of rot. Neither is welcome in a garden because both result in the death of the plant.

The Whole Leaf

If the whole leaf seems to be turning red -- or worse, several of the leaves -- the plant probably is infected with bacteria called Erwinia rhapontici. This is one of two conditions called red leaf, and in this case, the name is well earned. The entire leaf begins to turn red and the crown and the roots of the plant end up rotting. While seeing frilly red leaves might look pretty at first, it is a sign that the plant is severely infected. The only treatment for rhubarb infected with Erwinia is removal and destruction. You will not be able to plant rhubarb in the same spot again, and you will need to control insects in the area to avoid spreading the bacteria to other rhubarb plants.

Spots of Trouble

Two fungi, Ascochyta and Ramularia, cause a leaf spot disease that is also called red leaf. The leaves do not turn completely red, but they develop spots that have red margins. Harvest stalks with infected leaves quickly, but remove and destroy the plant at the end of the season. Burn or bag infected plant parts, although the plant will probably die within a couple of years. Aphids spread leaf spot fungi, so controlling aphids in your garden is essential.

Turnip Mosaic Virus

A condition caused by the turnip mosaic virus can occasionally cause reddish spots on rhubarb leaves. Turnip mosaic can be confused with Erwinia red leaf. This virus is spread by aphids, but controlling aphids does not seem to help much since the bugs can feed -- and spread the disease -- before they die.

Cultural Control

Rhubarb is grown for its stalks and not its leaves; the leaves contain such high levels of oxalic acid that eating the leaves could be fatal. This is a perennial plant that can live eight years, and after a few years, gardeners generally split the crowns and increase their plants. However, if the plant you split has any bacteria or viruses lurking, you could spread those diseases. Erwinia infections usually spread because an infected crown has been split and used to start a new planting. Use only certified disease-free crowns when adding new rhubarb plants to your garden. Clean up debris around the base of the plants and old leaves. Leaf spot fungi can hide among old leaves and over winter.

About the Author


Photo Credits

  • Martin Poole/Photodisc/Getty Images
Suggest a Correction