Hop-Root weevil

Includes

Black vine weevil (Otiorhynchus sulcatus)
Rough strawberry root weevil (Otiorhynchus rugosostriatus)
Strawberry root weevil (Otiorhynchus ovatus)

Pest description and crop damage Larvae are legless white grubs with tan heads. They overwinter 2 to 30 inches deep in the soil. Adults generally are black but may be brown. The smallest weevil, O. ovatus, is the most injurious. Larvae feed on plant roots. Adults feed on foliage but cause no significant damage.

Management-chemical control

  • azadirachtin (various formulations)-See label for rates. PHI 0 days. REI 4 hr. Works best on early larval stages. Applications can be repeated every 7 days or as needed. Some formulations are OMRI-listed for organic use.
  • bifenthrin (various formulations) at 0.06 to 0.1 lb ai/a. PHI 14 days. REI 12 hr. Do not exceed 0.1 lb ai/a per application or 0.3 lb ai/a per season. Minimum application interval is 21 days. For best results, apply as a foliar spray at night to the plant base and lower 3 feet of vine. Group 3A insecticide.
  • imidacloprid/bifenthrin (Brigadier, Swagger) by ground or air at 0.06 to 0.20 lb ai/a. REI 12 hr. PHI 28 days. Do not apply more than 0.1 lb ai/a of imidacloprid or more than 0.1 lb ai/a of bifenthrin per application. Do not apply more than 0.30 lb ai/a of any bifenthrin formulation or 0.30 lb ai/a of any imidacloprid formulation per season. Group 4A/3A insecticides.
  • pyrethrins/azadirachtin (Azera) at 0.013 to 0.0044 lb ai/a azadirachtin/0.014 to 0.048 lb ai/a pyrethrins. PHI 0 days. REI 12 hr. Apply when pest populations first appear. Reapply every 5-7 days as needed up to 10 times per season. Do not apply more than 0.050 lb ai/ a pyrethrins per season. Some formulations are OMRI-listed for organic use. Group 3 insecticide.
  • thiamethoxam (Platinum) at 0.125 lb ai/a. PHI 60 days. REI 12 hr. Do not exceed 0.266 lb ai/a per season. Apply (1) to the soil a band on each side of the hop row, (2) by drip irrigation into the root zone, or (3) as a hill drench. Incorporate band and hill drench applications with irrigation within 24 hr. Group 4A insecticide.

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