Field and silage corn-Corn rootworm

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.
  • 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. PHI 30 days. REI 24 hr. Do not exceed 0.3 lb ai/a foliar and at planting.
  • Bt/Diabrotica virgifera (Smartstax Pro Enlist). Refer to label instructions.
  • chlorethoxyfos/bifenthrin (Smart Choice 5G) at 0.2 to 0.25 oz ai/1,000 row ft. 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.
  • chlorpyrifos-
    • Lorsban 15G at 0.075 lb ai/1,000 row ft. PHI 21 days. REI 24 hr. Do not exceed 3 lb ai/a per season. Apply at planting as a band or at cultivation as a band or side-dress.
    • Lorsban Advanced at 0.94 lb ai/a post emergence broadcast. Chemigation permitted. PHI 21 days grain, ears, forage or fodder. REI 24 hr. Limit 3 treatments. Do not exceed 3 lb ai/a per season.
  • Chromobacterium subtsugae (Grandevo) at 0.05 to 0.1 lb ai/a per 1,000 row feet. PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • ethoprop (Mocap 15G) 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) 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) 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) 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 EC) 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) at 0.013 to 0.022 lb ai/a. PHI 0 days for green forage and 21 days for grain or fodder. REI 12 hr. Do not exceed four applications or 0.088 lb ai/a per season.
  • bifenthrin (Brigade 2EC) at 0.033 to 0.1 lb ai/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) at 0.04 to 0.1 lb ai/a. PHI 30 days grain and stover; 60 days forage. REI 12 hr. Do not graze for 30 days after treatment. Do not exceed 0.4 lb ai/a per season.
  • carbaryl (Sevin 4F) 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) at 0.059 to 0.098 lb ai/a. PHI 21 days. REI 24 hr. 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.
  • chlorpyrifos (Lorsban Advantage) at 0.47 to 0.94 lb ai/a. PHI 21 days. REI 24 hr. Do not exceed 3 lb ai/a per season. Apply as a postemergence broadcast spray or through overhead sprinklers.
  • Chromobacterium subtsugae (Grandevo) at 0.6 - 0.9 lb ai/a per 100 gal. PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • cyfluthrin (Tombstone) at 0.025 to 0.044 lb ai/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) at 0.018 to 0.022 lb ai/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) at 0.33 to 0.5 lb ai/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) at 0.03 to 0.05 lb ai/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) 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) 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) 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) 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) 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) 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.