If you’ve grown plants before, you know that the road to harvesting produce is not always smooth. Sometimes called pieplant, rhubarb is a cold-hardy perennial plant that many treat as a fruit once it reaches the kitchen. Although rhubarb plants are relatively easy to grow, they aren’t immune to rhubarb growing problems.
Check for common signs of trouble in your vegetable garden to ensure your rhubarb matures. One of the most common problems for rhubarb plants is leaf discoloration. Before reaching maturity, your rhubarb plant’s leaves may turn yellow or even red, signaling your plant is dealing with an issue as it grows.
Rhubarb is known for its bright red stems and leafy green foliage. Other common problems for gardeners trying to grow rhubarb are pests that threaten the health of your plants. Some pests enjoy feeding on the leaves of vegetables, leaving behind a skeleton of veins if left unchecked.
Rhubarb Diseases and Pests
Most issues for rhubarb plants come from bacteria or fungal infections and bugs that threaten the health of your maturing plant. With some intervention, your rhubarb plants survive these problems and make it to harvest.
Luckily, some of the issues that target rhubarb plants are not fatal and won’t prevent you from growing rhubarb plants quickly at home to make a delicious rhubarb pie.
Rhubarb Growing Problems: Leaf Spots
Several diseases may target rhubarb plants and cause discoloration of plant leaves. Red or yellow spots may spread across the green leaves of your crop.
Ascochyta is a genus of fungi that infects many types of plants. These fungi create small circular lesions on leaves that develop brown rings with a white center. After a few days of infection, the leaf spots turn brown and the leaves die.
Ramularia is another type of fungi in the same genus. The spots on rhubarbs become larger lesions, eventually turning white and tan with a purple border. Infected plants develop red dots, known as rhubarb rust spots.
The stalk of the rhubarb plant becomes infected. Rhubarb stalks develop white fungal growths that turn brown as the plant’s tissue dies.
Sanitation is the key to keeping the spread of the fungal spores under control. Infected plants infect other plants through direct contact or splashing water. Dispose of any contaminated plant debris and keep your gardening supplies clean to avoid spreading the fungus.
Anthracnose Stalk Rot
The first signs of anthracnose stalk rot are wilted leaves and large lesions growing on rhubarb stems. These lesions turn black and fill with water. The plant’s stems may become twisted and collapse in more severe infections.
Anthracnose is common in areas with cool weather and wet springs. Anthracnose is also common among stressed plants that are not healthy enough to resist the infection. Prevent further stalk rot by disposing of any infected stalks.
How to Handle Rhubarb Leaves Turning Yellow
There are a few reasons you may have rhubarb leaves turning yellow. Rhubarb is similar to other leafy greens and often displays similar growing problems. It grows large leaves that require lots of water to grow healthy, and if your plant lacks proper moisture, the leaves may turn yellow.
Watering too frequently may result in plant wilting. Having proper nutrients in the soil is another contributing factor to your plant’s health. Soil lacking in iron and nitrogen may result in your rhubarb leaves turning yellow. Water your plant every other day, or use a tester kit to measure the moisture and nutrients in your soil.
Phytophthora crown or crown rot is a disease that creates lesions on the leaf stalks. These lesions enlarge and cause the leaves of the plants to wilt, eventually collapsing the entire stalk.
Because diseases overwinter in the soil, avoid planting new plants in the same spot for at least four years. If the soil remains infected, your rhubarb crowns may continue to suffer from crown rot.
Reduce risk of infection in the leaves by planting rhubarb in the fall for best results. Plant rhubarb in well-draining soil in full sun with good air circulation. Preventative hydrogen peroxide treatments applied to your garden help kill pathogens and diseases.
Combine water and hydrogen peroxide in a tank sprayer or a watering can. Spray across your garden bed so it seeps into the soil. After treatments, water your plants as usual.
Common Pests for Rhubarb Plants
Curculios are large beetles that feed on the stalk of rhubarb plants. These beetles don’t typically cause severe damage, so mature plants are not at risk of serious harm. The beetles lay eggs on the stems of nearby weeds, so adding organic matter mulch around your rhubarb is the best way to keep these pests away.
The rhubarb stalk borer is another pest that lays eggs on weeds and overwinters in its egg stage. Leaf borers tunnel inside leaves to feed. Like beetles, remove nearby weeds to control the number of leaf borers near your rhubarb plants.
How to Grow Rhubarb (Rheum)
Rhubarb thrives in a cool climate but must undergo a dormancy period to produce impressive yields. As a perennial, rhubarb grows and produces stalks for many years.
Plant rhubarb in soil well-amended with material from your compost pile. Because rhubarb grows steadily for years, it’s best to put it in an area of the garden where it grows undisturbed or grow rhubarb in raised beds.
Purchase bare-root rhubarb crowns from your local nursery or garden center. The rhubarb crowns from the nursery have an established root system in peat moss or pots ready to transplant. Rhubarb plants are heavy feeders, so prepare a planting hole of at least four inches deep in fall or early spring.
Rhubarb leaves contain oxalic acid, which causes kidney problems in humans. The stalks of rhubarb plants contain this acid in a much lower concentration, safe for humans to eat.
Among the different varieties of rhubarb, there are red and green stalk types. Among green-stalk varieties, Victoria is one of the most popular. Victoria rhubarb is a favorite among gardeners for its thick stems and tart flavor.
The first year after you plant your rhubarb, you won’t be able to harvest any stalks. Slowly start harvesting rhubarb the second year and then harvest rhubarb regularly the third year. Don’t remove more than one-third of each plant’s stalks each growing season.
Divide your rhubarb plants every five years to avoid overcrowding. In early spring or fall, cut roots into sections roughly two inches across and replant these pieces to complete the propagation of your plant.
Rhubarb plants are excellent additions to a garden that adds bright color and unique flavor once you bring your crops into the kitchen. Resolve any rhubarb diseases and pests issues to ensure your crops reach maturity so you have the best yield possible.
If our article helped you understand common rhubarb growing problems, please share our guide with your fellow rhubarb gardeners on Facebook and Pinterest to spread information about typical rhubarb diseases and pests.