Rhubarb is generally robust and easy to grow. However, plants can become targets for common garden pests. Understanding how to identify these pests and their damage is crucial for maintaining healthy plants and ensuring a good harvest.
Identifying Common Rhubarb Pests and Their Damage
Several pests can affect rhubarb, each leaving distinct signs of their presence. Timely intervention requires recognizing these indicators.
Rhubarb Curculio (Lixus concavus) is a beetle that bores into rhubarb stalks, crowns, and roots. This half-inch, dark-colored beetle is often covered with yellowish, powdery material. Damage includes notches on stalks and leaf edges, with sap oozing from stems, sometimes collecting as glistening drops.
Slugs and snails are common garden nuisances feeding on rhubarb leaves, creating irregular holes, especially on younger foliage. Most active during damp conditions or at night, their presence is indicated by shiny slime trails on leaves and stalks. While they can cause extensive leaf damage, healthy rhubarb plants usually withstand slug and snail feeding since the leaves are not consumed by humans.
Aphids, particularly black bean aphids (Aphis fabae), infest rhubarb plants. These small, soft-bodied insects cluster on leaf undersides and stalks, sucking sap from the plant. Heavy infestations lead to curled or wilted leaves, yellowing foliage, and stunted growth. Aphids also excrete honeydew, attracting ants and encouraging sooty mold growth.
Stalk borers (Papaipema nebris) are caterpillars that tunnel into rhubarb stalks. These pests are pinkish-white, about 3.5 inches long. They lay eggs on surrounding grasses and weeds in fall; larvae hatch in spring and migrate to adjacent plants like rhubarb, boring into stalks. Stalk borer damage weakens stems, making them prone to wilting and collapse.
Leaf miners also affect rhubarb, though damage is primarily aesthetic. These larvae burrow within leaves, creating squiggly trails or blotchy patches. Trails appear translucent with white or yellow coloring. They can weaken plants and make them susceptible to other issues.
Preventing Rhubarb Pest Problems
Proactive measures minimize pest infestations and promote robust rhubarb growth. Healthy plants resist and recover from damage more effectively.
Proper site selection is foundational for prevention. Rhubarb thrives in well-drained soil and full sun, reducing humidity and discouraging moisture-loving pests like slugs and snails. Adequate air circulation, through proper plant spacing, deters fungal issues that weaken plants and increase pest susceptibility.
Maintaining garden cleanliness is important for deterrence. Removing plant debris, weeds, and organic matter around rhubarb eliminates hiding spots and breeding grounds for many pests, including slugs, snails, and overwintering curculio beetles. Weeds like dock and thistle can host pests like rhubarb curculio and stalk borers, so control them near your patch.
Ensuring overall plant health through proper watering and fertilization contributes to resilience. Strong, well-nourished rhubarb plants better withstand pest pressure than stressed ones. Consistent care helps maintain its vigor.
Encouraging beneficial insects in the garden provides natural pest control. Ladybugs, lacewings, and parasitic wasps prey on common pests like aphids, keeping populations in check. Creating a diverse garden environment with flowering plants attracts these helpful predators.
Effective Pest Control Strategies
Once pests are present, various control strategies mitigate their impact, prioritizing methods safe for edible plants and the environment. These approaches range from simple manual removal to organic solutions.
Manual removal is a simple, effective method for larger pests. Hand-picking visible pests like rhubarb curculio beetles, slugs, and snails significantly reduces their numbers. Dropping collected pests into soapy water effectively destroys them. For aphids, a strong water spray from a garden hose dislodges them.
Organic solutions offer another control layer. Insecticidal soaps apply directly to soft-bodied pests like aphids, disrupting protective waxes and leading to dehydration. Neem oil, from the neem tree, acts as an insect growth regulator and repellent. When using these products, follow label instructions carefully for dilution and application, applying during cooler parts of the day to avoid leaf burn.
Simple trapping methods are effective for slugs and snails. Shallow dishes with beer or a yeast-sugar-water mixture attract and drown these pests. Placing boards or damp newspaper near plants overnight creates hiding spots that attract slugs and snails, allowing easy collection and disposal in the morning.
Physical barriers deter certain pests from reaching rhubarb plants. A band of diatomaceous earth around plant bases deters slugs and snails, as its sharp particles abrade their soft bodies. Copper strips also act as a barrier; slugs and snails experience an unpleasant reaction when crossing copper.
Persistent or severe infestations might warrant other options. For edible plants, start with the least toxic methods and exhaust organic and cultural controls before stronger measures. Consulting a local extension office or plant specialist provides tailored advice for specific pest challenges.