R6 Stage: Physiological Maturity*
(Begins 55 - 65 days after silking.)
By the R6 stage, kernels have attained their maximum dry weight or dry matter accumulation. The hard starch layer has advanced completely to the cob. A black or brown abscission layer forms, moving progressively from the tip ear kernels to the basal kernels of the ear. It's a good indication of physiological maturity and signals the end of kernel growth. The husks and many leaves are no longer green, although the stalk may be.
GDUs Required** to reach R1 growth stage depends on maturity and is approximately:
|Scout for these Common Pests and Diseases||Timing*|
|Anthracnose Stalk Rot||R5 through R6.|
|Diplodia Ear Rot||R5 through R6.|
|Diplodia Stalk Rot||R5 through R6.|
|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.|
Click on the insect or disease for more information.
* 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.