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    R4 Corn Growth Stage and Scouting Tips

    R4 Corn Growth Stage - Dough
    R4 Corn Growth Stage - Dough

    Click on the above image for a larger view.

    R4 Stage: Dough*
    (Begins 24 - 28 days after silking.)

    Continued starch accumulation in the endosperm causes the milky inner fluid to thicken to a pasty consistency. Usually 4 embryonic leaves have formed as the embryo has grown dramatically from the R3 stage. The shelled cob is a light red to pink. Toward the middle of R4, the embryo will stretch across more than half of the width of the kernel side. Just before R5, kernels along the length of the ear begin to dent or dry. The fifth (last) embryonic leaf and the lateral seminal roots have formed. If this seed is planted, these 5 embryonic leaves will appear the following season after germination and VE.

    Tips*

    • The embryo continues to develop very rapidly.
    • Kernels are about 70% moisture and have accumulated about half their mature dryweight.

    GDUs Required** to reach R4 growth stage depends on maturity and is approximately:

    CRMGDUs
    801,570
    901,775
    1001,980
    1102,180
    1202,385
    ** Hybrid growth is influenced by the growing environment. Individual results may vary.

    Scout for these Common Pests and DiseasesTiming*
    Anthracnose Top DiebackR3 through R5.
    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.