The continued below average temperatures are slowing corn development significantly, says Joel Ransom, North Dakota State University Extension agronomist.
"There's a justifiable concern about the corn crop maturing late this season, particularly for fields that were planted late," he says.
According to the USDA NASS crop progress report for the week ending Aug. 4, corn silking in North Dakota was 81%, behind last year's 99% for the same time last year but ahead of 74% average. Corn at the dough stage was 3%, well behind 53% at the same time last year and the 16% average.
In South Dakota, corn silking was 87 percent as of the week ending Aug 4. That was behind 95% silking at the same time last year but ahead of 70% average. Dough was 15%, behind the 36% for last year at the same time, but near 14% average.
Corn that was silking the first week in August should mature in late October, if it receives another 900-1100 growing degree days during that period, Ransom says.
The following table relates growth stage to calendar days and GDDs maturity and the affect of frost on yield, moisture content and test weight at different stages. The ranges listed below are fairly large in order to take into account variances in temperature within the state and in the relative maturities of the hybrids grown, Ransom says.