Late-Season Nitrogen And Disease Management
GREG PFEFFER
DEXTER, MO.
Most of the corn crop in the north delta is late planted this year, and several places received more rain after planting than I can ever remember. Therefore, we may need to consider late-season nitrogen (N) needs and late-season disease control.
Recent research from DuPont Pioneer and universities provides insight to the value of late-season N applications. By flowering (R1), corn has taken up approximately 63 percent of its N requirement for the season. The rest is taken up during the grain-fill period (R1 to R6). Approximately 38 percent of this demand is remobilized from vegetative tissue; the rest is supplied from continued uptake after flowering. In high-yield environments, post-flowering N uptake can range from 85 to 130 lbs N/acre.
Late-season N applications should only be applied to fields with a yield potential greater than 170 bu/a. A pre-tassel application of N should be applied about two weeks prior to tassel. When the corn is four to five feet tall, tassel emergence is approximately 10 to 14 days away. Prior to a rainfall event or irrigation, 100 to 125 pounds of urea treated with AGROTAIN® can be applied to a firm and crusted soil resulting in good N use efficiency. AGROTAIN is an excellent N stabilizer that reduces the amount of N loss through ammonia volatilization.
The 2015 weather pattern also makes it a good year to consider fungicide applications for corn. Some growers do not treat every acre of corn, but focus their attention on the fields that are likely to get the greatest benefit from the fungicide applications. I recommend that growers target fields with high residue, especially corn following corn. Growers may also want to target fields planted with hybrids that are weak in disease tolerance.
In my experience, fields that have a later planting date seem to have a higher incidence of disease pressure earlier in the grain filling period. Also, it would be wise to consider fungicide applications in areas that have a history of higher disease pressure such as low lying areas or fields close to rivers where frequent leaf wetting would occur.
For more information, talk to your local Pioneer sales professional. ∆
GREG PFEFFER: Agronomist for Pioneer, Dexter, Missouri