Include a non-ionic surfactant at 2 pints per 100 gallons of mix, or crop oil concentrate at 1 gallon per 100 gallons of spray mix. 

This combination should be very effective on Palmer amaranth (>97 percent) and provide good control of horseweed and giant ragweed (85 to 95 percent).

The advantages to this combination are that it is in the mid-level price range and the metribuzin will provide some relatively inexpensive residual control.

The disadvantage is the trouble some are having with tank-mixes of paraquat products clabbering up in spray tanks. In order to reduce this problem be sure to add the surfactant first then acidify the water in the tank with some sort of AMS product (most often the surfactant and AMS are a pre-mix), then the metribuzin and last add the paraquat product. 

Liberty at a 29 ounce per acre rate is another option. Tank-mix of metribuzin will also help with control and provide some residual of Palmer amaranth. 

Research we just evaluated this week would suggest that AMS should not be added to Liberty as it reduces Palmer control.

This combination should be very effective on horseweed and giant ragweed (>97 percent) and provide good control of Palmer amaranth (>95 percent).

The advantage to this tank-mix is that with the warm temperatures it will be the most efficacious on Palmer amaranth and horseweed of the tank-mixes listed. 

The disadvantage is that it is the most expensive program listed. Moreover, many will likely rather use their Liberty in-crop and not as a burndown. 

The third tank mixture is Verdict or Sharpen tank-mixed with glyphosate. This combination will provide good control of horseweed and small pigweed (90 to 97 percent). Be sure to apply it with the MSO and surfactant as directed by the label. 

The advantage to this tank-mix is that it is fairly economically priced compared to the others. Moreover, it will provide some limited residual of Palmer amaranth.  

The most effective way to apply all three of the tank-mixes listed above is to ensure good converge. This is even more important on weeds that are cut in half. 

Thorough spray coverage is essential for optimal performance. Ground application requires a minimum of 15 gallons of water per acre, and preferably 20 gallons.

Moreover, be sure to utilize the adjuvants as directed by the label.