R5 Corn Growth Stage and Scouting Tips
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(Begins 35 - 42 days after silking.)
At R5, all or nearly all kernels are dented or denting. The shelled cob is dark red. The kernels are drying down from the top, where a small hard layer of starch is forming. This starch layer appears shortly after denting as a line across the back of the kernel (the non-embryo side). With maturity, the hard starch layer and line will advance toward the cob. Accumulated starch is hard above the line but still soft below the line.
GDUs Required** to reach R1 growth stage depends on maturity and is approximately:
|Scout for these Common Pests and Diseases||Timing*|
|Anthracnose Top Dieback||R3 through R5.|
|Anthracnose Stalk Rot||R5 through R6.|
|Diplodia Ear Rot||R5 through R6.|
|Diplodia Stalk Rot||R5 through R6.|
|European Corn Borer||Second-generation egg masses are laid in late-July through August.|
|Fusarium Ear Rot||R5 through R6.|
|Fusarium Stalk Rot||R5 through R6.|
|Gibberella Ear Rot||R5 through R6.|
|Gibberella Stalk Rot||R5 through R6.|
|Stewart's Wilt||Disease is initiated with corn flea beetle feeding from VE to V5. Leaf symptoms appear after R1.|
|Western Bean Cutworm||Scout ear tips for feeding.|
* Information from Pioneer and Iowa State University Extension.
Use this information as a guide and it should not be the only factor in making decisions.