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

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)

Related Species

• 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

Herculex® I hybrid (left) vs.YieldGard® Corn Borer hybrids (center and right)