V12 Corn Growth Stages and Scouting Tips

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V15 Corn Growth Stage

V12 Stage*

The potential of kernels per row is determined by at least V15 and maybe as early as V12. The top ear shoot is still smaller than the lower ear shoots, but many of the upper ears are close to the same size.


  • Moisture or nutrient deficiencies from V10 to V15 significantly reduce kernel numbers, ear size and grain yield.
  • Earlier-maturing hybrids progress through growth stages in less time and generally produce smaller ears than later-maturing hybrids. Thus early-maturing hybrids need high plant densities for maximum yields.

GDUs Required** is approximately 910 to reach V12 stage.

** These GDUs apply to a 105- to 110-day hybrid grown in the Central Corn Belt. Hybrid growth is influenced by the growing environment. Individual results may vary.

Scout for these Common Pests and Diseases Timing*
Common Rust V12 through R4.***
Corn Earworm Date of arrival of adult moths from southern states varies each year. Corn at VT to R1 is most attractive to egg-laying females. Scout at R1 or when a significant moth flight is captured in pheromone traps.
Corn Rootworm Larval feeding on roots is most extensive in early through mid-July in most regions of the Corn Belt.
Eyespot V6 through R4. Disease found primarily in northern environments.
Goss's Wilt VE through R6. Disease primarily found in Nebraska and portions of other western states.
Gray Leaf Spot VT through R4.***
Japanese Beetle Scout from VT through R1, until pollination is complete.
Northern Leaf Blight VT through R4.***
Southern Leaf Blight VT through R4.***
Western Bean Cutworm Initiate scouting based on local pheromone trap captures of adults. If trap data are unavailable, begin scouting at VT through R1.

Click on the insect or disease for more information.

* Information from Pioneer and Iowa State University Extension.

*** Scout for these diseases earlier in seed production fields.

Use this information as a guide and it should not be the only factor in making decisions.