Bob Nielsen

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Given the near record late planting of the 2019 Indiana corn crop and the continuing agony of delayed development of the crop, much of the coffeeshop talk down at Cecil’s Corner Cafe in recent weeks has centered on the risk of the late crop not maturing before a light frost damages the crop or an outright lethal freeze (28F) kills the crop.


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Delayed planting of corn in the upper Midwest often increases the risk that the grain will not mature prior to a killing fall freeze. Physiological maturity occurs near the time the so-called “black layer” develops at the tips of the kernels where they connect to the cob (Nielsen, 2019a).



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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.




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Twisted whorls sometimes develop in young corn plants early in the rapid growth phase. The cause is not well understood. The tightly twisted whorls eventually unwrap to reveal yellowish upper leaves that turn green after a few days of exposure to sunlight. Effects on yield are essentially nil. The curious phenomenon often referred to as the “twisted whorl syndrome” is beginning to show up in some fields in recent days. This “problem” often occurs when young corn shifts quickly from weeks of slow development (cool, cloudy weather) to rapid development (warm, sunny weather). Earlier planted corn has certainly experienced such a change in weather conditions in recent weeks. The occurrence of the twisted whorl syndrome is not uncommon, but rarely affects a large number of fields in any given year or a large percentage of plants within a field. The typical growth stage when growers notice the twisted whorls is[Read More…]