Bob Nielsen

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Droopy ears are cute on certain breeds of dogs, but droopy ears on corn plants prior to physiological maturity are a signal that grain fill has slowed or halted. Ears of corn normally remain erect until some time after physiological maturity (black layer development) has occurred, after which the ear shanks eventually collapse and the ears decline or “droop” down. The normal declination of the ears AFTER maturity is desirable from the perspective of shedding rainfall prior to harvest and avoiding the re-wetting of the kernels. PREMATURE ear declination, however, results in premature black layer formation, lightweight grain, and ultimately lower grain yield per acre.





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The grain fill period begins with successful pollination and initiation of kernel development, and ends approximately 60 days later when the kernels are physiologically mature. During grain fill, the developing kernels are the primary sink for concurrent photosynthate produced by the corn plant. What this means is that the photosynthate demands of the developing kernels will take precedence over that of much of the rest of the plant.


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Field corn in Indiana typically enters the critical flowering stages of pollen shed and silk emergence sometime between late June to late July. Success or failure during this period of the corn plant’s life greatly influences the potential grain yield at harvest time.


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The silks that emerge from the ear shoot are the functional stigmas of the female flowers of a corn plant. Each silk connects to an individual ovule (potential kernel). A given silk must be pollinated in order for the ovule to be fertilized and develop into a kernel. Up to 1000 ovules typically form per ear, even though typically only 400 to 600 actual kernels per ear survive until harvest.