By Keith Robinson
August 28, 2014
Indiana corn is developing ahead of the weather-damaged crop of 2009 when similarly wet conditions left much of the grain infected with fungal diseases at harvest, Purdue Extension corn specialist Bob Nielsen says.
But uncertainties for some of the crop still lie ahead. Nielsen noted that there are concerns that this year's crop could suffer the same fate as the 2009 crop, which matured late, dried down slowly before harvest and was laden with ear rots and mycotoxins - toxic substances produced by the fungi that cause some ear rots.
"The good news is that the progress of the 2014 Indiana corn crop is roughly two weeks ahead of the 2009 corn crop at this point," Nielsen said in a late-August update on the crop. Nielsen will discuss his report in detail at several field days for farmers over the next couple of weeks.
"If crop progress continues at this pace, the bulk of the state's corn crop should mature between early and late September, in contrast with the 2009 crop that matured during the first three weeks of October," he said. "Consequently, field drydown of the grain prior to harvest should occur under relatively more favorable climatic conditions than that of 2009, resulting in faster drydown and a lower risk of delayed grain harvest."
Nielsen said some areas had excessive rainfall early this growing season, damaging or killing young plants, and areas that missed rains are showing symptoms of mid-season drought stress. Some fields sustained damage from wind or hail storms throughout the summer, and some were affected by early outbreaks of foliar diseases such as northern corn leaf blight or gray leaf spot.
"Granted, growing conditions have not been perfect everywhere, but severe crop stress has nevertheless been restricted to relatively few acres," Nielsen said, noting that the U.S. Department of Agriculture's National Agricultural Statistics Service so far has rated at least 70 percent of the statewide crop in good to excellent condition the entire season.
As a result, Nielsen agrees with the NASS estimate that this year’s Indiana crop could produce 179 bushels per acre, two more than the record 2013 crop. The NASS also projects total production at a record 1.04 billion bushels.
Nielsen said, however, some fields could sustain damage from excessive rain that fell in some parts of the state the third week of August, and fields in more areas of the state are showing symptoms of nitrogen deficiency. Although warmer, muggier conditions might cause an increase in late-season foliar diseases, corn in most areas is far enough along that it will not affect yield.
With ear rots already appearing in some fields, Kiersten Wise, Purdue Extension specialist for field crop diseases, encouraged farmers to scout their fields for the symptoms of Gibberella and Diplodia ear rots. The fungus that causes Gibberella ear rot produces the mycotoxin deoxynivalenol (DON or vomitoxin), and grain buyers will be testing for the presence of this mycotoxin in grain this fall. Fields with Gibberella should be harvested as early as possible and grain dried to below 15 percent moisture content. If this corn is left in the field or in the bin above that moisture content, it will be at increased risk for mycotoxin accumulation.
Fields with severe photosynthetic stress - from foliar disease, hail damage, nitrogen deficiency, waterlogging and drought stress - during the latter half of the grain filing period also should be harvested as early as possible, Nielsen said.
"Time will tell whether these will become a major issue in the 2014 crop," he said. "I am hopeful that the combination of 'normal' maturation in mid- to late September, coupled with, hopefully, favorable field drydown conditions will minimize this threat."
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