Northwest berry Foundation

Management Detail

Weevil, Strawberry Root

in Raspberries

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Latin name: Otiorhynchus ovatus

Description:

Reason for Concern:
1) One of numerous weevil species found in caneberries. It has been the predominant species and contributes to serious economic losses.
2) Emerge in early May and June, can be machine-harvested fruit contaminant.
3) Grubs weaken cane growth by devouring roots, which destroys bark and cortexes.

Identification/Symptoms:
Larvae are white or pink, legless, "C" - shaped grubs. In the larval stage, size is the only characteristic that distinguishes one species from another. About 9 mm long when fully grown with distinct brown heads. They can be found in soil during most of winter and summer. Adults are flightless, hard-shelled beetles, oblong oval in shape, and about ¼” long. They have a broad snout, long, downward curved mouthparts and elbowed antennae. Body is shiny blackish-brown and the wing covers have numerous small pits and small hairs. They feed at night and hide around plant crowns during the day.

Life Cycle:
Adults (nearly all females) appear post bloom, beginning in May and continuing through and after harvest. They climb canes at night to feed on foliage. They lay eggs around the crowns about 1 month after emergence. They lay several eggs each day and usually lay 200 eggs during their adult lifetime (90-100 days). Eggs hatch in 2 to 3 weeks. Larvae burrow into the soil and feed on roots and crowns, grow slowly over summer, and molt 5 to 6 times. By late fall, they have matured to about 5/8” long, enter a prepupal stage in an earthen cell and pupate the following spring/summer. There is one generation per year.

Links:

Scouting:

  • In early-mid April, begin taking 10 beating tray samples from several sites in the field (monitoring technique developed by Washington State University, Whatcom County Raspberry IPM Manual), and record the number found. This is most effective at night or on cool cloudy days as this is when weevils will stay in the foliage.
  • In late May, begin examining foliage for weevil feeding signs (notching of the leaf margins).
  • 1 or 2 weevils found for every 10 beating tray samples taken may warrant the consideration of a pre-harvest spray to target those weevils.

 
Cultural Controls:

None listed at present.

 

For information about chemical controls, check with our Pesticide Guide.

images


photo by K. Gray


photo by A. Antonelli

 

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Northwest Berry Foundation

Northwest Berry Foundation

© 2016

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