Extremely dry conditions in late August and September have not only reduced corn and soybean yields in Indiana, but will make harvest conditions very difficult. According to the latest USDA crop brief, Indiana corn and soybeans are drying down very quickly. Purdue corn specialist Bob Nielsen says this will likely result in very weak stalks, “Severe stress this late in the growing season, especially during grainfill after successful pollination and kernel set, can cause plants to ‘cannibalize’ themselves to meet carbohydrate needs of developing grain.” Corn plants taking stored carbohydrate reserves in lower stalk and leaf tissues and moving them to developing ears can cause weakening of lower stalks and higher risk of root and stalk rots.
According to Nielsen, harvesting this year’s stressed corn may be a challenge, “Such cannibalized or diseased plants are naturally more apt to break over or lodge in response to strong winds, potentially turning grain harvest into a frustrating and challenging operation.” He recommended that, “Growers ought to be walking drought-stressed fields during the next several weeks to assess the presence and severity of weakened stalks, then work toward prioritizing the weakest fields for early harvest to minimize the risk of significant mechanical harvest yield losses.”
Talk of improving yields as grainfill began just a few weeks ago has given way to discouragement as hot dry conditions have significantly reduced Indiana yield potential. “Plain and simple, the ‘frosting is off the cake’ for many cornfields around Indiana as dry and often excessively hot conditions continue through the end of this 2013 grain-filling period,” Nielsen said. “In fact, for some fields, the ‘cake’ is disappearing, too.”
According to Nielsen, there is a common misconception that growers don’t have to worry about yield potential when corn has hit dent. “Once corn reaches dent stage, many folks can be heard confidently stating that there is no reason to worry about further crop stresses because ‘the crop is made,'” he said. “Actually, by the time a crop reaches full dent, only about 60 percent of the crop has been ‘made’ and there is still 40 percent of the potential yield on the table yet to be determined.” In fact, corn plants can still fall victim to sudden and complete death as late as two weeks before physiological maturity if conditions are bad enough. Whole plant death can translate to yield losses as high as 12 percent. “A crop is not ‘made’ until it has successfully reached physiological maturity,” he stated.
The situation is not any better for soybeans. Soybean specialist Shawn Casteel says harvesting soybeans may also be impacted by this year’s crop stress, “Many of the plants have put on pods very close to the ground and this will be very difficult if not impossible to harvest.” The latest report indicated some Indiana soybean fields were beginning to shut down because of the late season drought.