WHAT ARE ROOT WEEVILS AND WHAT DO THEY DO?

Root weevils are one of the most common insect pests in most landscapes. They attack rhododendrons, azaleas, viburnum, laurel, photinia, and virtually any other plant. The adults typically notch the margin of leaves while the larvae eat the roots. The adult damage is unsightly, but the larval destruction of the roots may be lethal to the plant. Once leaves on plants like rhododendrons are notched, they are unsightly until the plant sheds them.

WHY ARE THEY SO DIFFICULT TO CONTROL?

Most pesticides will not kill root weevils. Root weevils are widespread in “wild” or greenbelt areas where they feed on salal or Oregon grape. They readily migrate from these areas to your planted landscape.

They do most of their damage from early April through October, and primarily damage newly emerged, young, tender leaves. The WSU extension service recommends monthly treatments during this period, if the problem is serious.

WHAT CAN I DO TO REDUCE ROOT WEEVIL PROBLEMS?

Plant rhododendrons that are resistant to root weevils. The WSU extension service has a bulletin that lists resistant varieties. Keep the ground under susceptible plants free of leaves and debris to reduce adult hiding places. You can also discourage root weevils from attacking your plants by removing branches which touch the ground.

If you're trees and shrubs are regularly treated by us, we treat for root weevils on a regular basis during warmer months. If you have plants with serious problems, you may want to do additional treatments between our visits. If you're trees and shrubs aren't regularly treated by us, call us for an evaluation and estimate to treat your landscape.

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