Cool temperatures and frost have slowed development of Indiana corn for farmers who planted earlier this year than ever before, a Purdue Extension corn specialist says. According to the U.S. Department of Agriculture’s National Agricultural Statistics Service, an estimated 6 percent of Indiana’s corn crop was planted by April 8, and that number increased to 24 percent by the following week. Cold temperatures, frost and wind damaged many of the seedlings – some fatally. “Probably the best way to describe the general condition of the crop to date is that it is behaving like a crop that was planted in late March and early April,” said Bob Nielsen. “Many of the surviving fields are light green to almost yellow. Almost all of the fields are developing slowly relative to calendar time but are on schedule relative to the more typical cool April temperatures and the resulting slow accumulation of growing-degree days.”
Growing-degree days are a measure of heat accumulation to predict plant development rates. It takes about 115 GDDs for corn to emerge. In a typical Indiana March, GDDs would be almost zero. But because of the unusually warm air temperatures and subsequent warm soil temperatures, the average daily accumulation of soil temperature-based GDDs was about 8-12 per day in the central part of the state, Nielsen said.
When April temperatures fell to normal or below normal, the GDD accumulation slowed to a more normal rate, meaning there were very few GDDs per day. “Nothing about this is unusual, but growers should recognize that early-planted corn in Indiana sometimes faces challenges, not just from typical frost or freeze events in April, but also due to the fact that crop development in April is typically slow from a calendar perspective,” Nielsen said.
One thing he said producers could have done to give the crop a better chance of survival was liberal application of starter fertilizer. “The role of starter fertilizer is to assist young corn plants as they make the transition from kernel reserves to nodal roots during times when root development or function is compromised by less-than-optimum growing conditions,” Nielsen said.
The return of warm weather this week in Indiana is something he said is welcomed by the early-planted crop, as has been the rainfall in areas of the state that were unseasonably dry in March and April.