This spring drug on for many growers in the Midwest where the continual rain and cool temperatures slowed crop growth and development. But when the heat finally turned on, so did the crop. This is often referred to as the “rapid growth” phase of corn which occurs between the sixth leaf and tassel. As these plants grow, so does their demand for water and key nutrients like nitrogen. Brandon Nystrom is the AgriGold Regional Agronomist for Missouri and parts of Iowa and has been watching the crop very closely. According to research, more than 50% of a corn crops’ nitrogen needs are met during this time frame before pollination. But now that many fields are at, or close to, pollination, does that mean the demand for nitrogen has been fully met?
“Absolutely not,” says Nystrom. “The demand for N throughout the grain fill period is still high as plants pollinate and start packing kernels. Over half of the total N uptake by plants is used to produce grain and the last thing growers want is to be set up for high yields just to fall short at harvest due to a lack of N.”
In a year of heavy spring rains nitrogen loss is a concern. One useful tool is the University of Missouri’s Nitrogen Watch website which helps identify key areas of concern. Nystrom believes that rescue applications of nitrogen can be made through pollination with a few studies showing responses even later. He also points out that adequate nitrogen is important for maintaining plant health and stalk integrity later in the season.
“Several areas throughout the Midwest have received 16 inches or more of rainfall since April. It’s in these areas where growers should really keep a watchful eye on their crop and consider an in-season application if they believe they will run short,” Nystrom explained.
Protect what you have
As plants progress towards grain fill, stalk integrity becomes an even bigger concern. Beyond maintaining adequate crop nutrition, Nystrom believes that protecting the canopy now will help keep plants upright at harvest.
“A healthy canopy will help maintain healthy stalks,” he says.
A major reason for this is that a stressed canopy will have a harder time keeping up with the demand of the plant which can lead to earlier cannibalizing and stalk degradation. If the environment is disease-prone or already has a disease presence, then a grower may consider a fungicide.
“We’ve seen some fantastic results using timely fungicides in the past few years. Many of AgriGold’s NCGA winners factor it into their program every year,” says Nystrom.
He claims that most data shows the best time to apply a fungicide for highest return on investment is typically at or shortly after tassel emergence. However, results can vary between different combinations of hybrids and fungicides.
Know your hybrids
Another significant factor when it comes to stalk quality is differences in hybrid genetics. According to Nystrom, not all hybrids are created equal. While some hybrids may have an excellent green snap score, that does not always indicate great late season standability or tolerance to specific stalk rots.
“As agronomists, it is our job to know and explain to growers both the good and the bad,” said Nystrom. “I utilize AgriGold’s hybrid classification system, Field GX, and my own knowledge of each product to help growers make decisions such as when to spray or when to harvest.”
He believes that growers can maximize yield and avoid standability issues if they know their areas of concern and each hybrid’s strengths and weaknesses.