Based on the number of calls coming in, a combination of 1) applying N in early February (especially liquid N) and 2) continued wet weather has led to N deficiency symptoms showing up in some wheat fields.  Variations in green color within a field can be due to application method as well as weather or soil conditions.  Typical N deficiency symptoms are: bright yellow green color with yellow lower leaves and poor tillering.  A plant tissue test will help to confirm N deficiency and separate it from yellowing caused by low sulfur or low pH.  Widespread N deficiency that is visible after all N has been applied– particularly where early N was applied- may require some additional N in some fields.

What Rate to Apply?  The goal is to apply a modest amount of ‘corrective’ fertilizer without going too high this late in the season especially where rates above 100 lbs N/A have already been applied.  Too much N this late could cause lodging and potentially more diseases in the crop.  A modest rate would be 30 lbs N/A applied as dribbled UAN or granular N flown on the field.  Spraying UAN broadcast is risky and on a hot, sunny day could cause tremendous leaf burn which we do not need this late in the season.  Corrective N must be applied before the flag leaf is fully visible.  The closer to flag leaf N is applied, the less effective it will be in turning a crop around.