A discussion of rhubarb root crown rot, also known as stem rot, root rot and foot rot. Learn about phytophthora species fungi and what you can do if your rhubarb has crown rot.
What Is It?
Rhubarb crown rot is a plant disease which is aternately known by the names stem rot, foot rot, and root rot. Rhubarb crown rot is caused by the phytophthora species of fungi, and can be caused by any one of several fungi in this classification. Most often rhubarb plants, which are infected with phytophthora species fungi causing crown rot, causes the entire plant to die off after damage has been done to the leaves, leafstalks, stems and roots of the rhubarb plant.
What Does It Look Like?
Damage from rhubarb crown rot first manifests in rhubarb leaves which tend to turn brown and then begin to have sunken and water-soaked spots on them. These fungally affected rhubarb leaves then wilt quickly. Sunken, water-soaked spots also appear on the leafstalks of rhubarb plants which have been infected with phytophthora species fungi causing crown rot. Rhubarb leaves will eventually turn yellow on infected rhubarb plants and then the rhubarb stalks progress to a very weak point where they bend and then die. As the phytophthora species fungal infection progresses it inevitably kills off the entire rhubarb plant if left untreated with fungicide.
How Does It Manifest?
Rhubarb plant crown rot beings when phytophthora species fungi attack and invade rhubarb plants at the plant crowns and root stems. Plant crows are the juncture on the rhubarb plant where the stems and roots meet. The phytophthora species fungi which cause rhubarb crown rot thrive in heavy soils which are easily waterlogged with excessive moisture. Once the phytophthora species fungi has attacked the rhubarb plant, it quickly causes the stems and roots of the plant to rot, rapidly wilting the plant as it travels through it's nourishment system and infects leaves and stalks. The phytophthora species fungi which causes crown rot becomes most active in its spread during temperatures of 60° to 75° F which often occur in late spring or early summer months. Spores of this fungi are spread by either splashing water, rain or running water around infected soil and plants and quickly spread from infected to healthy plants by this means.
What Can I Do About It?
When you first notice the signs of rhubarb crown rot, make sure you remove and destroy all plant leaves which show signs of infection. You can try to save the plant by spraying a captan or basic copper sulfate fungicide to the plant at the crown and base as well as to all surrounding soil. However, once the The phytophthora species fungi has infected the rhubarb plant and begun crown rot it is likely your plant will die. If you elect to remove the entire infected plant it is best to do so carefully to prevent spread of fungal spores to nearby healthy plants. You will also want to spray the previously mentioned fungicides around the crown, base and soil of nearby healthy plants to prevent spread of the fungi. Overwatering can spread spores, so avoid this action. Also, when you plant rhubarb you should always make sure you are getting your transplants from a reputable company and that you purchase disease-free plants.
