Last spring a good many folks went back “old school” and applied glyphosate alone for burndown and saw very good results. This includes applications made when nighttime temperatures were below freezing (Picture 1).

Part of the reason for this success was that the glyphosate was applied in a fashion that gives it the best chance for success, meaning at 10 gpa or less.  Glyphosate moves much more readily from the spray droplet into the weed when the droplets have a higher concentration of glyphosate.  Also, the glyphosate was applied with a good surfactant system.

Another reason for this success is that herbicides like dicamba or atrazine were left out of the tank as they can regularly hinder grass control of glyphosate.  The final reason is that glyphosate-resistant horseweed pressure in many fields was very scarce.

In fields that were infested with horseweed, the addition of Elevore controlled that weed and did not appreciably set back grass control of glyphosate.  Unfortunately, Elevore is in limited supply currently. So what other options are there? The addition of Sharpen or Verdict to glyphosate can be a very effective option for overall good burndown including horseweed.

As we transition to late spring applications, adding something for residual weed control can be a good plan.  Herbicides like Leadoff can enhance glyphosate control of larger ryegrass while providing residual control of late-emerging horseweed and grasses.  Corn may be planted immediately after a Leadoff application while a 30-day waiting period is needed before planting soybean or cotton.