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Carpenter Costin Blog

Rhododendrons VS Black Vine Weevil

Overview

The Black Vine Weevil (BVW) is an insect pest that injures plants, Rhododendrons being top choice throughout the US. In Massachusetts there are few natural predators of this species. 

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Adult Black Vine Weevils

The adult weevil is dark gray to black and has subtle white flecking. It has a short broad snout. It can lay as many as 300 eggs near plants over a period of 2-3 weeks. Eggs are laid near the base of the plants and will hatch in two weeks. Black Vine Weevils do not fly so they crawl from shrub to shrub. During daytime the adults hide in dark places; soil, garden debris, lead litter, mulch and even the crevices of the plant. The adult feeding rarely causes serious plant injury, however the feeding habit of the notching of leaves is evidence the pest is present. Action should be taken to mitigate damage by the next generation of BVW. 

Black Vine Weevil -

Black Vine Weevil Larvae

BVW Larvae are a creamy-white color with a brown head. They are the most destructive stage of the Black Vine Weevil. In August, the C-shaped larvae begin tunneling through roots and can girdle the stem feeding just below the soil line on cambium and cause plant death. When the BVW feeds it can cause nutrient deficiencies and poor functioning roots. If the plant has nutrient deficiencies or poor functioning roots the leaves yellow, wilt and plants can die. Thinner foliage is more susceptible than a thicker plant. 

Recommendations

BVW is an active feeder that will quickly drop to the ground if disturbed. This is when foliar applications work best. We recommend doing the following:

  • Pruning rhododendrons so foliage does not touch the ground reducing the Black Vine Weevil's access to the shrubs
  • Clear leaf litter to keep BVW from being able to hide underneath it
  • Apply two Summer Foliar Treatments
  • Fertilize your plants
  • Remove dead or infested foliage to limit overwintering sites

Are you seeing notches on your Rhododendron leaves? Is the damage so extensive that the entire leaf edges are jagged and unsightly? Give us a call now, young new growth is the particular foliage of choice for the BVW. We have more than one control option available.

Keeping plants healthy and happy is the first defense, fertilization is recommended!

If you have any questions about Black Vine Weevil or are interested in any of our services please do not hesitate to contact us at 877-308-8733 or click the link below!

Request A Free Consultation

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