farmgate: A Corn Growing Enigma Has Possibly Been Solved.
Immature ears of corn may be popular at restaurant salad bars, but not in your cornfield at harvest time. And beginning in the 2007 crop year, many farmers who frequently found them were becoming as pickled as the salad ingredient. Yield and revenue certainly go down as the number of immature ears increases. An explanation for the problem has been found, and your corn growing practices may need to change to prevent the problem on your farm.
You can’t credit the CSI Miami folks for solving the riddle, but the pat on the back goes to Purdue corn specialist Bob Nielsen, who has found the answer to—what agronomists call--arrested ear development. He says it is quite different from the periodic problem of blunt ears or “beer can” ears, and his report on the problem attributes the halt in ear maturity to the application of herbicides, fungicides, and insecticides with certain additives in the spray, at the time the length of the ear is being determined within the corn plant.
Nielsen and his Purdue colleagues attempted to reproduce the problem. “Three fungicides, one insecticide (I), a commercial non-ionic surfactant (NIS), crop oil concentrate (COC), glyphosate (GLY), ammonium sulfate (AMS), and 2,4-D were applied in various combinations over the canopy of corn on July 18th, at approximately the V14 stage of leaf development (approximately 5 ft tall and 1 - 2 weeks prior to tasseling).” Nielsen says at that stage of plant development, ear size determination was essentially complete, silks were beginning to elongate, and the tips of the ear shoots were visible in the leaf axis in most plants. Nielsen reported that five days after the spray application, it was apparent the surfactant had penetrated to the ear shoot and the upper end of the young cob had begun to dissolve.
Neither the fungicides themselves or with an insecticide caused any problems, but when a crop oil concentrate or non-ionic surfactant was added, problems grew from 3% to 35%. Adding glyphosate increased the problem to 60%. With the growing popularity of a fungicide application to corn as a preventative measure, Nielsen says there were no problems with arrested ear development in conjunction with the practice, but he says there were fewer kernels per ear with those treatments.
The use of foliar herbicides with a spray additive resulted in some severely arrested ears. Problems up to 40% resulted from glyphosate plus 2,4-D; a non-ionic surfactant alone; a crop oil concentrate alone, or ammonium sulfate alone. One of the problems was a shorter cob length, but the glyphosate and ammonium sulfate treatment also curtailed kernel numbers as well.
Nielsen says the bottom line is the knowledge that certain combinations of foliar pesticides and spray additives, when applied at the V-14 leaf stage, have the potential to stop development of the ear of corn, and suspend it in a state of frozen animation.
Summary:
Cornbelt farmers who have been baffled over the increasing number of immature ears of corn at harvest time, may have an answer about the cause of “arrested ear development.” The application of various pesticides, blended with tank mix additives, such as crop oil concentrates and non-ionic surfactants, and applied at the stage of ear development when length is determined may be the cause of the problem. Although more research has to be done, corn growers would be advised to adjust one of the variables to avoid the problem in the future.
Posted by Stu Ellis on December 24, 2008 12:06 AM to farmgate