Common Rhubarb Plant Diseases:
How to Identify and Treat

Rhubarb is a popular and versatile perennial vegetable that is grown for its tart and tangy stalks. However, like any other plant, rhubarb is susceptible to various diseases that can affect its growth and overall health. Identifying these diseases early on and implementing appropriate treatment measures is crucial in ensuring a successful rhubarb harvest. In this article, we will discuss some common rhubarb plant diseases, their symptoms, and effective treatment options.

1. Rhubarb Crown Rot

Rhubarb crown rot is a fungal disease caused by various species of fungi belonging to the Phytophthora genus. This disease primarily affects the crown of the rhubarb plant, which is the area at the base of the stalks where they emerge from the ground.

Symptoms: Infected plants may exhibit wilting, yellowing, or browning of leaves. The crown may appear soft and mushy, with a foul odor. In severe cases, the entire plant may collapse and die.

Treatment: To prevent crown rot, it is important to ensure proper drainage in the planting area. Avoid overwatering and provide good air circulation around the plants. If crown rot is already present, remove and destroy infected plants immediately to prevent further spread. Avoid planting rhubarb in areas where this disease has occurred in the past.

2. Rhubarb Leaf Spot

Rhubarb leaf spot is a common fungal disease caused by the fungi Mycosphaerella pontederiae and Ramularia rhei. It primarily affects the leaves of the rhubarb plant.

Symptoms: Infected leaves develop small reddish-brown spots that gradually enlarge over time. These spots may have a grayish center and can coalesce to form larger irregular lesions. Severe infections can cause defoliation and weaken the plant.

Treatment: To manage leaf spot, remove and destroy infected leaves as soon as symptoms appear. Avoid overhead watering, as wet foliage provides favorable conditions for fungal growth. Applying a fungicide labeled for use on rhubarb can also help control leaf spot, following the instructions provided by the manufacturer.

3. Rhubarb Crown Gall

Rhubarb crown gall is a bacterial disease caused by the bacterium Agrobacterium tumefaciens. It primarily affects the crown and roots of the rhubarb plant.

Symptoms: Infected plants develop galls or tumor-like growths on the crown and roots. These galls may vary in size and can hinder the plant’s ability to take up nutrients and water. Affected plants may exhibit stunted growth, wilting, and decline over time.

Treatment: Unfortunately, there is no cure for crown gall once a plant is infected. The best approach is prevention through the use of disease-free planting material and avoiding injury to the plant’s roots during cultivation. If crown gall is detected in a planting bed, it is advisable to remove and destroy all infected plants and avoid replanting rhubarb in that area.

4. Rhubarb Powdery Mildew

Rhubarb powdery mildew is a fungal disease caused by the fungi Erysiphe polygoni and Microsphaera polonica. It primarily affects the foliage of the rhubarb plant.

Symptoms: Infected leaves develop a white or grayish powdery coating on the upper surface. As the disease progresses, the coating may spread to cover the entire leaf surface. Severe infections can cause leaf distortion, yellowing, and premature defoliation.

Treatment: To manage powdery mildew, prune or thin out dense foliage to improve air circulation. Remove and destroy infected leaves to prevent further spread of the disease. Applying a fungicide labeled for use on powdery mildew can also help control the disease, following the instructions provided by the manufacturer.

5. Rhubarb Rust

Rhubarb rust is a fungal disease caused by the fungus Puccinia recondita f.sp. polygoni. It primarily affects the leaves of the rhubarb plant.

Symptoms: Infected leaves develop small yellow or orange pustules on the undersides. These pustules may eventually rupture, releasing rusty brown spores. The upper leaf surface may exhibit yellowing and premature defoliation.

Treatment: To manage rust, remove and destroy infected leaves as soon as symptoms appear. Avoid overhead watering, as wet foliage provides favorable conditions for fungal growth. Applying a fungicide labeled for use on rust can also help control the disease, following the instructions provided by the manufacturer.

In conclusion, being aware of common rhubarb plant diseases and their symptoms is essential for maintaining the health and productivity of your rhubarb plants. By implementing appropriate treatment measures and practicing good cultural practices, such as proper watering and adequate air circulation, you can effectively manage these diseases and ensure a bountiful rhubarb harvest. Remember to always follow label instructions when using fungicides to control plant diseases. Happy gardening!