Fall Armyworm
Pest Injury Symptoms and Impact on Crop
- Fall armyworm larvae feed inside whorls on young plants
- Feeding injury in leaves ranges from small shot holes to large ragged and elongated holes
- Deep feeding in whorl may destroy developing tassel
- Defoliation reduces photosynthetic area, which may stunt plants and reduce yield
- Larvae will enter through the side of the ear and feed on developing kernels, reducing grain quality and yield
Pest Facts of Fall Armyworm
- Latin name is Spodoptera frugiperda
- Are some of the most important pests in corn worldwide, especially in tropical climates, where they reside year-round in high numbers
- Native to the southern United States and especially damaging on second plantings
- Does not overwinter in most of the Corn Belt but moves north during the season on storms
- Wide host plant range, including:
- Corn, soybeans, cotton, bermudagrass, rice
- Many broadleaf plants
- Many small grains
- Favorable conditions:
- Semi-tropical and tropical climates
- Late-planted corn in whorl stage
- Natural enemies include parasitic wasps and flies, but these cannot reliably keep the pest in check
- Unlike the regular armyworm and other moth larvae, the fall armyworm normally feeds during the day
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Parasitic wasp larvae clustered on a parasitized fall armyworm caterpillar |
Key Characteristics of Fall Armyworm
- Brown/gray larva with distinct tubercles along body
- Three thin white stripes down the back and a distinct white inverted "Y" on head
- Young larvae may be difficult to distinguish from corn earworm (CEW)
- True Armyworm (AWM)
- Subdued colors, present in large numbers
- Smooth cuticle
- Corn Earworm (CEW)
- Bright, variable colors
- Cuticle has "unshaven" look
- Yellow Striped Armyworm (YSA)
- Very bright, with yellow stripe
- Dark spot
Life Cycle of Fall Armyworm
IPM Practices
- Scouting - scout late-planted fields as they reach V5-V8. Thresholds for treatment are based on defoliation levels and potential for FAW larvae entering the ear.
- Pesticides are only effective on young larvae and before they enter the ear
- Utilize early planting to avoid this and other pests
Management Considerations Using Pioneer Products
- Pioneer Bt corn hybrids with Herculex® I or Herculex® XTRA provide a high level of resistance to FAW
- Hybrids with only the YieldGuard® Corn Borer gene are much less effective
- Biological controls: Parasitic wasps / flies - not reliable
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Herculex® I hybrid (left) vs.YieldGard® Corn Borer hybrids (center and right) |
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