By Scout Nelson
University of Minnesota Extension specialists recently shared insights on nitrogen management and small grain pest updates. Dr. Fabian Fernandez and Dr. Jochum Wiersma discussed these topics in the June 4 Field Notes program.
Nitrogen levels in the soil are currently stable. Because of minimal runoff and limited rainfall, nitrogen loss through denitrification or leaching is low. However, nitrogen mineralization remains slow due to fluctuating spring temperatures. As temperatures stabilize, mineralization will increase, improving nitrogen availability.
Corn growers are advised to apply sidedress nitrogen between the V4 to V8 growth stages for best results. Applying nitrogen too late—after V12—may reduce yield. Fernandez recommends earlier application to meet crop needs and minimize nitrogen loss.
Nitrogen sources vary in loss risk. For example, surface-applied UAN may lose nitrogen unless followed by at least half an inch of rain. Knifing or injecting nitrogen into the soil is a more efficient method. Anhydrous ammonia should also be applied early to avoid root damage. Nitrification inhibitors are not usually needed unless extremely wet conditions arise.
Cover crops may temporarily tie up nitrogen due to microbial activity. In such cases, applying 40 lbs/acre of nitrogen can help crops grow until a full sidedress is applied.
For small grains, fungal disease risk models like the Small Grain Disease Forecasting Model help predict threats such as Fusarium head blight (FHB), tan spot, Septoria, and leaf rust. FHB risk increases with consistent warm, humid weather, especially before heading.
Insect pest activity has remained low this season. Armyworms and aphids, which usually arrive via southern winds, have not been a concern yet.
Farmers are encouraged to monitor local weather models and scout fields to make informed decisions for healthy and productive crops.
Photo Credit: university-of-minnesota
Categories: Minnesota, Crops, Corn