VT Corn Growth Stages and Scouting Tips

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VT Corn Growth Stage

VT Stage*

The VT stage arrives when the last branch of the tassel is completely visible. VT begins about 2 to 3 days before silk emergence. The plant is nearly at its full height. Pollen shed begins, lasting about 1 week on an individual plant basis and 1 to 2 weeks on a field basis. The interval between VT and R1 can fluctuate considerably depending on the hybrid and the environment. Drought stress lengthens this interval.


  • With the tassel and all leaves exposed, the plant is extremely vulnerable to hail from VT through silking (R1). Total removal of leaves can devastate yield potential.
  • If ovules aren't fertilized they produce no kernels on the cob.

GDUs Required** to reach VT depends on maturity and is approximately:

80 920
90 1,075
100 1,175
110 1,280
120 1,420
** Hybrid growth is influenced by the growing environment. Individual results may vary.

Scout for these Common Pests and Diseases Timing*
Corn Earworm 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 is most extensive in early through mid-July in most regions of the Corn Belt.
European Corn Borer As the true stalk develops and European corn borer larvae increase in size, larvae can be found tunneling into the stalk.
Eyespot V6 through R4. Disease primarily found 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 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.
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.