Otiorhynchus spp.

Description

Root weevils feed on the leaves of shrubs as adults and on roots as larvae. Both lifestages of the insect cause extensive damage to landscape plants. Though there is only one generation each year, the feeding can continue year round causing exaggerated damage to plants in one growing season.

Symptoms & Diagnosis

Feeding damage induced by adult weevils manifest as notching along the margins of foliage. Larval feeding of root systems is particularly damaging with risk of the root crown becoming girdled. Plants will become stunted, chlorotic, and fail to produce new growth with enough damage. Heavy larval infestation causes eventual death.

Treatment

Root weevil adults and larvae are controlled through foliar and soil applications. Properly timed treatments throughout the year will ensure control of both stages of root weevil. Contact applications for adult weevils should be reserved for late in the day as adults are nocturnal feeders.

Management

Managing tree stress is a crucial component of insect management. Tree can remain healthier and aesthetically pleasing longer by properly managing water, avoiding compaction and grade changes, and controlling insects. Fertilization improves plant vigor.

Affected Species

• Rhododendron spp. (Rhododendron)
• Rhododendron spp. (Azalea)