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    R2 Corn Growth Stage and Scouting Tips

    R2 Corn Growth Stage - Blister
    R2 Corn Growth Stage - Blister

    R2 Stage: Blister*
    (Begins 10 - 14 days after silking.)

    R2 kernels are white on the outside and resemble a blister. The endosperm and its now-abundant inner fluid are clear. The embryo is still developing, but it now contains a developing miniature corn plant. Much of the kernel has grown out from the surrounding cob materials. The cob is close to full size. Silks are darkening and beginning to dry out. Starch has just begun to accumulate in the watery endosperm. Kernels are beginning to accumulate dry matter. Seed-fill is beginning.

    Tips*

    • Nitrogen and phosphorus are accumulating rapidly and relocating from vegetative to reproductive parts of the plant
    • The kernels are about 85% moisture and will dry down from this point.

    GDUs Required** to reach R1 growth stage depends on maturity and is approximately:

    CRMGDUs
    801,305
    901,470
    1001,635
    1101,800
    1201,965
    ** Hybrid growth is influenced by the growing environment. Individual results may vary.

    Scout for these Common Pests and DiseasesTiming*
    Common RustV12 through R4.***
    Corn RootwormLarval feeding is most extensive in early through mid-July in most regions of the Corn Belt.
    European Corn BorerAs the true stalk develops and European corn borer larvae increase in size, larvae can be found tunneling into the stalk.
    EyespotV6 through R4. Disease primarily found in northern environments.
    Goss's WiltVE through R6. Disease primarily found in Nebraska and portions of other western states.
    Gray Leaf SpotVT through R4.***
    Northern Leaf BlightVT through R4.***
    Southern Leaf BlightVT through R4.***
    Stewart's WiltDisease is initiated with corn flea beetle feeding from VE to V5. Leaf symptoms appear after R1.
    Western Bean CutwormInitiate 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.