Pacific Northwest Insect Management Handbook

Field and silage corn-Corn rootworm beetle

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Image related to Field and silage corn-Corn rootworm
Western corn rootworm
Diabrotica virgifera virgifera LeConte
Showing damage on roots
© Ken Gray Insect Image Collection
Image related to Field and silage corn-Corn rootworm
Western corn rootworm
Diabrotica virgifera virgifera LeConte
Adult
© Ken Gray Insect Image Collection
Image related to Field and silage corn-Corn rootworm
Western corn rootworm
Diabrotica virgifera virgifera LeConte
Egg(s) on host
© Ken Gray Insect Image Collection
Image related to Field and silage corn-Corn rootworm
Western corn rootworm
Diabrotica virgifera virgifera LeConte
Immature
© Ken Gray Insect Image Collection

Diabrotica spp.

Pest description and crop damage West of the Cascades D. undecimpunctata is most common; east of the Cascades D. virgifera is common. Mature larva is 0.5 inch long, pale yellow, with a brown head and dorsal anal plate. Larvae feed on and mine into corn roots causing stunting and lodging of plants and stand reduction.

Management-cultural control

Crop rotation helps to reduce infestations from D. virgifera as eggs overwinter in soil. The adults of D. undecimpunctata overwinter, therefore crop rotation is not as important in managing this species.

Management-chemical control

Seed treatments

  • abamectin/thiamethoxam (Avicta Duo Corn)-Requires tank mix. Apply as slurry to corn seed. Consult label.
  • clothianidin (Poncho 600) at 1.25 mg ai/kernel or 0.22 lb ai/80,000 seed unit. Commercial treaters only.
  • Chromobacterium subtsugae (Grandevo) bioinsecticide at 0.05 to 0.1 lb ai/A per 1,000 row feet (1.0 to 3.0 lb product /A). PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • imidacloprid (Gaucho 600)-Refer to label for planter box treatment. REI 24 hr.
  • thiamethoxam (Cruiser 5FS) at 1.25mg ai/kernel.

Larvae treatments

  • bifenthrin/indol butyric acid (Empower 2) at 0.005 to 0.006 lb ai/1,000 row ft (8.0 ounces or 0.006 lb ai/100 linear feet of row) to larvae. PHI 30 days. REI 24 hr. Do not exceed 0.3 lb ai/A foliar and at planting plus foliar application per season.
  • Bt/Diabrotica virgifera (Smartstax Pro Enlist). Refer to label instructions.
  • chlorethoxyfos/bifenthrin (SmartChoice 5G, SmartChoice HC) Group 1B insecticide-SmartChoice HC granular application rate at 1.5 to 1.67 oz ai/1,000 row ft; SmartChoice 5G 4.5 to 5.0 oz/100 ft of row with 30 inch row spacing in field and seed corn. REI 2 days or 3 days where annual rainfall is less than 25 inches. T-band over the row or apply in-furrow. Apply with Smartbox system. Do not exceed one application per year.
  • ethoprop (Mocap 15G) nematicide/insecticide at 1.2 oz ai/1,000 row ft. REI 48 hr or 72 hr where annual rainfall is less than 25 inches. One application per season. Incorporate in band above seed row.
  • gamma-cyhalothrin (Declare) Group 3 insecticide at 0.0025 lb ai/1,000 row ft at planting. REI 24 hr. Do not exceed 0.045 lb ai/Acre at plant and 0.06 lb ai/A per season.
  • lambda-cyhalothrin (Warrior II) Group 3 insecticide at 0.005 lb ai/1,000 row ft (planting). PHI 21 days. REI 24 hr. Do not exceed 0.12 lb ai/A from at plant and foliar applications.
  • phorate (Thimet 20G) at 0.056 to 0.075 lb ai/1,000 row ft at plant or cultivation, broadcast or banded but not in-furrow. PHI 30 days to cutting or forage. REI 48 hr. Use only once per season.
  • tefluthrin (Force 3G) Group 3 insecticide at 0.0075 to 0.094 lb ai/1,000 row ft. REI 0 hr. T-band or in-furrow at planting. Do not exceed 0.327 lb ai/A per year. Use only once per season.
  • terbufos (Counter 15G) at 0.056 to 0.075 lb ai/1,000 row ft. Do not exceed 1.3 lb ai/A per season. REI 48 hr or 72 hr if annual rainfall is less than 25 inches. May be side-dressed at cultivation time if preplant treatment was not made. To be effective, apply before corn is 12 inches high.

Adult treatments

  • alpha-cypermethrin (Fastac CS) Group 3A insecticide at 0.017 to 0.025 lb ai/A. REI 12 hr. PHI 30 days grain and stover; 60 days forage. Retreatment interval 3 days. Do not exceed 0.075 lb ai/A per season.
  • beta cyfluthrin (Baythroid XL) Group 3 insecticide at 0.013 to 0.022 lb ai/A (1.6 to 2.8 fl oz/A). PHI 0 days for green forage and 21 days for grain or fodder. REI 12 hr. Maximum 2.8 fl oz/A in 7-day interval. Do not exceed four applications or 0.088 lb ai/A per season.
  • bifenthrin (Brigade 2EC) Group 3A insecticide at 0.033 to 0.1 lb ai/A (2.1 to 6.4 fl oz/A). PHI 30 days for harvest, grazing, or cutting for feed. REI 12 hr. Do not apply more than 0.3 lb ai/A per season. Rootworm adults only.
  • bifenthrin/zeta-cypermethrin (Hero EW) Group 3A insecticide at 0.04 to 0.1 lb ai/A (4.5 to 11.2 fl oz/A). Only for use on corn rootworm adults. PHI 30 days grain and stover; 60 days forage. REI 12 hr. Do not graze for 30 days after treatment. Do not exceed 0.1 lb ai/A at-plant application, or 0.4 lb ai/A per season.
  • carbaryl (Sevin 4F) insecticide at 1 to 2 lb ai/A. PHI 14 days for forage or silage, 48 days for grain or fodder. REI 24 hr. Do not exceed four applications or 8 lb ai/A per season. Re-treat every 14 days. Latex-based formulations, such as Sevin XLR Plus, are less hazardous to bees.
  • chlorantraniliprole/lambda-cyhalothrin (Besiege) Group 3 & 28 insecticide at 0.052 to 0.08 lb ai/A (6.0 to 10.0 fl oz/A). PHI 21 days. REI 24 hr. As part of an aerial applied corn rootworm control program, use minimum of 9.0 fl oz/A. Do not exceed 0.12 lb ai of lambda-cyhalothrin or 0.2 lb ai of chlorantraniliprole per acre per growing season. Retreatment interval 7 days.
  • Chromobacterium subtsugae (Grandevo) bioinsecticide - at 0.6 to 0.9 lb ai/A per 100 gal. PHI 0 days (2.0 to 3.0 lb product /A). REI 4 hr. OMRI-listed for organic use.
  • cyfluthrin (Tombstone) insecticide at 0.025 to 0.044 lb ai/A (1.6 to 2.8 oz/A). PHI 0 days for green forage and 21 days for grain or fodder. REI 12 hr. Retreatment interval 7 days. Do not exceed four applications or 0.175 lb ai/A per season.
  • deltamethrin (Delta Gold) Group 3 insecticide at 0.018 to 0.022 lb ai/A (1.5 to 1.9 fl oz/A). PHI 21 days for grain or fodder, or 12 days for forage or grazing. REI 12 hr. Do not apply more than 0.095 lb ai/A per season. Retreatment interval 21 days. Limit 5 treatments per year.
  • dimethoate (Dimethoate 400 EC) Group 1B insecticide/miticide at 0.33 to 0.5 lb ai/A (0.6 to 1 pint/A). PHI 14 days forage; 28 days grain. REI 48 hr. Do not exceed 0.5 lb ai/A per season. Do not apply if bees are foraging actively.
  • esfenvalerate (Asana XL) Group 3 insecticide at 0.03 to 0.05 lb ai/A (5.8 to 9.6 fl oz/A). PHI 21 days. REI 12 hr. Do not exceed 0.25 lb ai/A per season.
  • GS-omega/kappa-Hxtx-Hv1a (Spear Biological Insecticide) at 0.8 lb ai/A. PHI 0 days. REI 4 hr. Do not exceed 2 lb ai/A per year.
  • indoxacarb (Steward EC) Group 22 insecticide at 0.059 to 0.11 lb ai/A. PHI 14 days grain, 1 day forage, fodder, silage. REI 12 hr. Limit 2 treatments. Do not exceed 0.22 lb ai/A per year.
  • lambda-cyhalothrin (Warrior II) Group 3 insecticide at 0.02 to 0.03 lb ai/A. PHI 21 days. REI 24 hr. Do not apply more than 0.12 lb ai/A per season, 0.06 lb ai/A after silk initiation, or 0.03 lb ai/A after milk stage.
  • malathion (Gowan Malathion 8, Fyfanon 8) at 0.6 to 1 lb ai/A. PHI 5 days. REI 12 hr. Limit 2 treatments per year. Retreatment interval 7 days.
  • methomyl (Lannate SP) Group 1A insecticide at 0.22 to 0.45 lb ai/A. PHI 21 days for ears, 3 days for forage, and 21 days for fodder. REI 48 hr. Do not exceed 2.25 lb ai/A or 5 treatments per season. Retreatment interval 5 to 7 days.
  • permethrin (Ambush 25W) wettable powder insecticide at 0.1 to 0.2 lb ai/A. PHI 0 days for forage, 30 days for grain harvest or fodder. REI 12 hr. Allow 6 days between applications. Do not apply more than 0.6 lb ai/A per season.
  • tebuconazole/lambda-cyhalothrin (Crossover) Group 3 fungicide/insecticide at 0.14 to 0.16 lb ai/A. PHI 21 days fodder and silage. REI 24 hr. Retreatment interval 7 days. Do not exceed 0.48 lb ai/A tebuconazole or 0.12 lb ai/A lambda-cyhalothrin per season.
  • zeta-cypermethrin (Mustang) Group 3A insecticide at 0.034 to 0.05 lb ai/A. PHI 7 days for grain, stover and forage. Do not exceed 0.2 lb ai/A per season. REI 12 hr. Retreatment interval 3 days.

Kaur, N. (Ed.). 2023 Pacific Northwest Insect Management Handbook.
© Oregon State University.

Use pesticides safely!

  • Wear protective clothing and safety devices as recommended on the label. Bathe or shower after each use.
  • Read the pesticide label—even if you’ve used the pesticide before. Follow closely the instructions on the label (and any other directions you have).
  • Be cautious when you apply pesticides. Know your legal responsibility as a pesticide applicator. You may be liable for injury or damage resulting from pesticide use.

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