1. Insect
  2. Agronomic Crops
  3. Field and Silage Corn Pests

Field and silage corn-Armyworm

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Image related to Field and silage corn-Armyworm
Beet armyworm
Spodoptera exigua Hubner
Immature female adult
© Ken Gray Insect Image Collection
Image related to Field and silage corn-Armyworm
Beet armyworm
Spodoptera exigua Hubner
Egg(s) on host
© Ken Gray Insect Image Collection
Image related to Field and silage corn-Armyworm
Beet armyworm
Spodoptera exigua Hubner
Adult
© Ken Gray Insect Image Collection

Includes

Armyworm (Pseudaletia unipuncta)
Beet armyworm (Spodoptera exigua)

Pest description and crop damage Outbreaks are more severe in cooler, wet conditions. Armyworm larvae are most threatening from August through October. Mature larvae are 1.5 inches long. Color varies from brown (armyworm) to green. Moths occasionally are attracted to weeds in corn fields.

Management-chemical control

For best results, apply treatments when armyworms are small to medium size (0.25 to 0.75 inch).

  • alpha-cypermethrin (Fastac CS and Fastac EC) Group 3A insecticide at 0.02 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.
  • azadirachtin (Aza-Direct, Azaguard and several formulations) Biological insecticide/nematicide at 0.02 to 0.35 lb ai/A. PHI 0 days. REI 4 hr. Some formulations are OMRI-listed for organic use.
  • Bacillus amyloliquefaciens D747 TGAI/bifenthrin (Ethos 3D, Ethos XB) at 0.04 to 0.2 lb bifenthrin ai/A. Do not exceed 0.3 lb bifenthrin on field corn per season. REI 12 hr. PHI Group 3A insecticide, Group 44 fungicide.
  • Bacillus thuringiensis (Javelin WG) biological insecticide at 0.5 to 1.5 lb/A. PHI 0 days. Use according to individual manufacturer's label instructions. OMRI-listed for organic use.
  • 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. Do not exceed four applications or 0.175 lb ai/A per season.
  • bifenthrin Group 3A insecticide/miticide -
  • Brigade 2EC at 0.033 to 0.1 lb ai/A foliar, 0.04 lb ai/A preemergence, or 0.047 to 0.062 lb ai/A preplant incorporated. 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. Do not apply Capture LFR as foliar treatment.
  • Sniper LFR at 0.04 to 0.16 lb ai/A. Apply as T band over open furrow or in-furrow with seed. Do not apply more than 0.2 lb ai/A at plant. Field corn-Do not exceed 0.3 lb bifenthrin/A/season including pre-plant.
  • Capture LFR at 0.04 to 0.2 lb ai/A (3.4 to 17.0 fl oz/A).
  • bifenthrin/chlorantraniliprole (Elevest) at 0.098 to 0.167 lb ai/A. REI 12 hr. PHI 30 days. No more than three applications per year. Do not apply more than a total of 0.2 lb ai/A of chlorantraniliprole and 0.3 lb ai/A of bifenthrin per year. Group 3A and 28.
  • bifenthrin/zeta-cypermethrin (Hero EW) Group 3A insecticide at 0.04 to 0.1 lb ai/A foliar or at planting (4.5 to 11.2 fl oz/A). See label for row spacing or per linear feet. 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 0.099 lb/A zeta-cypermethrin and 0.398 lb/A bifenthrin per year.
  • Burkholderia spp. (Venerate XC) bioinsecticide at 1 to 4 quarts/A. PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • carbaryl (Sevin 4F) insecticide at 1 to 2 lb ai/A. PHI 14 days for forage or silage grazing, and 48 days for grain harvest. REI 24 hr. Do not exceed four applications or 8 lb ai/A per season. 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. 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. Use higher listed rates within listed range for large larvae.
  • chlorantraniliprole (Coragen) Group 28 insecticide at 0.045 to 0.098 lb ai/A. PHI 14 days. REI 4 hr. Do not exceed 4 treatments or 0.2 lb ai/A per season. Retreatment interval 7 days.
  • Chromobacterium subtsugae (Grandevo) bioinsecticide at 0.3 to 0.9 lb ai/A per 100 gal (1.0 to 3.0 lb product /A). PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • cyfluthrin (Tombstone) insecticide-Apply to 1st and 2nd instar only at 0.025 to 0.044 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. 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, and 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.
  • 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.
  • gamma cyhalothrin (Declare) Group 3 insecticide at 0.01 to 0.015 lb ai/A. Effective on first and second instar larvae only. PHI 1 day for grazing and forage, or 21 days for fodder and silage. REI 24 hr. Do not exceed 0.06 lb ai/A per season.
  • GS-omega/kappa-Hxtx-Hv1a (Spear Biological Insecticide) at 0.8 lb ai/A. PHI 0 day. 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.
  • methomyl (Lannate SP) Group 1A insecticide at 0.22 to 0.45 lb ai/A. PHI 21 days for ears, 3 days for forage, 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.
  • methoxyfenozide (Intrepid 2F) Group 18 insecticide at 0.06 to 0.25 lb ai/A. PHI 21 days. Do not exceed 1 lb ai/A per season. REI 4 hr.
  • methoxyfenozide/spinetoram (Intrepid Edge) Group 5 and 18 insecticide at 0.094 to 0.281 lb ai/A. PHI 28 days. REI 4 hr. Do not exceed 0.625 lb ai methoxyfenozide and 0.125 lb ai spinetoram per acre per year. Limit 3 treatments. Retreatment interval 4 days except 2 days for silking.
  • permethrin- Group 3 insecticides -
    • Ambush 25W at 0.1 to 0.2 lb ai/A foliar or as preemergent. 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.
    • Loveland Permethrin Cutworm Bait at 0.1 to 0.15 lb ai/A. REI 12 hr. PHI 0 days for forage; 30 days for grain harvest or fodder. Retreatment interval 7 days. Do not exceed 0.45 lb ai/A per season.
    • Pounce 1.5G at 0.0075 to 0.015 lb ai/1,000 row ft soil or 0.1 to 0.15 lb ai/A broadcast. PHI 0 days for forage; 30 days for grain harvest or fodder (stover). REI 12 hr. Apply in furrow or as band at planting. Retreatment interval 7 days. Do not exceed 0.45 lb ai/A per season.
  • spinetoram (Radiant SC) Group 5 insecticide at 0.023 to 0.047 lb ai/A. PHI 3 days forage or fodder; 28 days grain. REI 4 hr. Do not exceed 0.125 lb ai/A per year. Do not exceed 3 treatments. Retreatment interval 4 days.
  • spinosad (Success) Group 5 insecticide at 0.023 to 0.094 lb ai/A. PHI 28 days grain or fodder; 7 days forage. REI 4 hr. Do not exceed 0.188 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 0.04 to 0.05 lb ai/A. PHI 7 days for grain, stover and forage. Apply no more than 0.2 lb ai/A per season. Retreatment interval 3 days.