When I apply 28% UAN to winter wheat can I also add a herbicide?

Written by Mike Cowbrough

Mike Cowbrough

Areas of Focus • Weed management systems for field crops • Editor of Guide to Weed Control Publication 75

  • A good question. The research is certainly excellent with consistent results across several environments. In my opinion, the biggest concern is that the results may not be the same in later-planted wheat. At most experimental locations in this research, the wheat was planted relatively early (before the bulk of the winter wheat in Ontario was planted); this wheat was well-advanced in development and well-tillered. In fact, early-planted wheat lose tillers without yield reductions.

    Just a speculation, but applying a stress that results in significant leaf injury to wheat plants struggling to maintain active tillers (which is a primary cause for lower yields in late-planted wheat) would probably result in the abortion of tillers that are already limiting yield potential. Managing late-planted wheat to maintain tillers is the primary reason for applying some N early at green up. I would agree with the authors in the summary!