Warmer temperatures in late June and early July have helped improve the crop conditions in some areas of the Midwest.
Earlier planted corn has made up some lost ground as far as crop development, while later planted corn and soybeans have experienced very rapid growth.
However, many areas of southern and western Minnesota, along with adjoining areas of northern Iowa and eastern South Dakota, have been impacted by severe storms and excessive rainfall in recent weeks, including hail in some locations. Some fields have considerable drown-out areas and many fields show crop damage.
Crop conditions remain quite variable across the region.
Other than the heavy rainfall, late June and early July featured normal to above-normal temperatures, which has allowed for rapid development of corn and soybeans in many areas of the Upper Midwest.
As of July 3, the accumulated growing degree units (GDUs) at the University of Minnesota Research and Outreach Center at Waseca since May 1 was 881.5, about 10 percent behind normal. However, this is a big improvement from early June, when the GDUs at Waseca were 23 percent behind normal. The GDU accumulation in 2019 at Waseca is still short of that in 2018 when 1143.5 GDUs had been accumulated by July 3.
The continued heavy rainfalls in late June and early July have hampered crop development and caused additional crop loss. Most of the affected region received 100 to 150 percent, or more, of their normal precipitation since May 1, with heaviest rainfall coming since mid-June.
For the year, many areas have now received 20 to 30 inches of precipitation, with portions of southeast and western Minnesota getting 5 to 10 inches of rain since June 25.
In some areas of southwest Minnesota and eastern South Dakota, farm operators did not complete their 2019 corn and soybean planting until late June. There is a considerable number of prevented planted acres in many locations.
The excessive rain is raising concerns about the loss or lack of available nitrogen for the growing corn. Soil nitrogen losses increase substantially during heavy rainfalls early in the growing season.
In some cases, farmers planned to side dress the nitrogen after planting, but have been unable to do so because of the saturated field conditions.
Farmers may need to evaluate the condition of the corn crop before deciding how much to invest in supplemental nitrogen applications.
Another concern is herbicide applications for weed control. Farmers relying on post-emergence herbicides for weed control have had difficulty getting these products applied, resulting in strong weed pressure in some fields.
We have already passed the time window for dicamba herbicide in soybeans, as well as for some other post-emergence herbicides used in corn and soybeans. Producers should contact their agronomist or crop consultant regarding further considerations for late season post-emergence herbicide options for this year’s crop.
The weekly USDA Crop Condition Report on July 1 listed 58 percent of Minnesota’s corn crop and 62 percent of the soybeans as good to excellent. For comparison, the good to excellent crop ratings in Minnesota at this time in 2018 were 84 percent for corn and 79 percent for soybeans.