Sunshine helped corn and soybean growth this past week. Several farm calls were requested and many had to do with poorly growing, yellow corn.

As you drive around the counties, there are areas of yellow and green corn within fields. This can be attributed to ammonia application. Yellow corn has not come in contact with the ammonia nitrogen application zone and green corn plants have reached those zones. As corn nears 15” in height, corn roots extent across the row middles. Corn roots will reach ammonia and corn will turn green. We have not lost nitrogen at this time.

Also in one field, corn planting was delayed following ammonia application but still had roots burned. The soil was very dry and fluffy during application and also tilled. The ammonia application zone had spread farther than what would be typical.

Holcus leaf spot is an early season corn disease and causes light brown lesions on the leaves. This disease was found in several fields and is caused by bacteria. Most hybrids have adequate resistance and being bacteria, a fungicide will not be effective.

Also, a few corn fields had carryover from long lasting soybean herbicides. This is typical during cool springs. The corn plants have a hard time metabolizing the herbicide during cool temperatures and symptoms include stunting and buggy whipping of plants. Typically, damage will be short sections of individual corn rows show damage.

Now is time to conduct stand counts and scout fields for any injury. Corn will enter into the period of rapid growth and corn with adequate nitrogen will turn dark green.

For more information, contact Wayne Flanary, Field Specialist in Agronomy, at 816-279-1691, University of Missouri Extension.