By Scout Nelson
A recent Field Notes session hosted by UMN Extension offered insights into post-June rain field conditions. The focus was on nitrogen application strategies and early-season disease development in Minnesota.
For nitrogen timing, experts advise not delaying sidedress applications without strong justification. “It’s either in the soil profile in a plant available form when the plant demands it – or it’s not.” Nitrogen should ideally be in place by the V12 corn growth stage. Equipment trends show more farmers using Y-drop nozzles or their own machinery for quicker in-season applications.
Urease inhibitors are now more affordable and effective for urea treatments in dry or uncertain weather. They help reduce volatilization risk but need at least 0.25 inches of rain to work. Nitrification inhibitors, typically used in the fall, are less needed in-season due to the short uptake window.
Regarding rainfall and nitrogen loss, saturated soils pose a risk. However, moderate rainfall is unlikely to cause serious nitrogen loss unless drainage is poor. Denitrification becomes a concern with high soil temps and extended saturation. “Twenty-five percent of the nitrogen in UAN is already in nitrate which is the most easily lost form.”
In terms of crop diseases, Pythium root rot is winding down, while Rhizoctonia is being observed in soybeans. Phytophthora remains a season-long concern due to resistance issues. Later-season threats include sudden death syndrome (SDS), tar spot in corn, and white mold in soybeans, with development highly dependent on July–August conditions.
“Use IPM Pipe Tar Spot webpage to track where tar spot has been reported so far this season across the nation on a county level.”
The key advice is to monitor soil conditions, apply nitrogen in a timely manner, and stay alert for developing diseases as the season progresses.
Photo Credit:gettyimages-studio2013
Categories: Minnesota, Crops, Corn, Soybeans, Weather