Worm Pests on Roots of Rhubarb

Cutworms

• Cutworms are green to black and are found in soil surrounding the rhubarb plant. They eat the roots and stalks and cause the plant to decline in health and die if not managed. The best control methods are picking them hand and using an insecticide containing permethrin, cyfluthrin or carbaryl.

Rhubarb Curculio

• Adult stage rhubarb curculios cause extensive damage by burrowing into the stalks. Although often considered the worst of rhubarb pests, their larvae cause just as much damage. The brown to yellow, wormlike larvae are less than an inch in length. They are hard to spot in soil. If unchecked, they eat the rhubarb roots to the point that they become inefficient. There are no insecticides for management. The best control measure is picking and destroying them as they appear.

Wireworms

• The wireworm is yellowish brown becomes between 1 to 2 inches long. Wireworms are common pests for most vegetables, and they can quickly wipe out large portions of crops. Rhubarb is one of the vegetables that it attacks less often, but if a gardener is noticing rhubarb root pests and cannot identify them as anything else, this could be the problem. Wireworms reside in the soil and eat away at the plant's roots. Once they appear, picking them by hand is the only control measure. Use a special insecticide on the soil before planting the next batch of rhubarb.

Japanese Beetle Larvae

• The larvae produced by Japanese beetles are stubborn rhubarb root pests. These white-to-yellow, wormlike pests are usually around 1 inch in length. They stay in the soil surrounding the plant and eat the roots. Gardeners may have to sift through soil daily to check for them, or they could go unnoticed. Combine pesticide applications with picking them away by hand.