Jim Ritchie's article in this issue of Today's Farmer addresses glyphosate formulations. This column is a companion to that article. My comments are based upon information obtained from university research, manufacturer specification and practical experience working with these materials.

All formulations of glyphosate are not identical. Compound concentration, appropriate application rates and additive recommendations are product specific. Glyphosate products and rates currently distributed by MFA Incorporated can be found in the Agronomy section of this website. Please pay close attention to these tables when determining glyphosate application rates. For example, a 32-ounce rate of Roundup Ultra is equivalent to a 26-ounce rate of Roundup UltraMax. Applying equal rates of these materials may result in poorer efficacy of the Roundup Ultra.

Another consideration is choice of additives needed to improve glyphosate activity. For example, it is recommended that ammonium sulfate (AMS) be added to all glyphosate formulations. However, when using original Roundup or Touchdown 5, a non-ionic surfactant (NIS) is also recommended. By applying either one of these materials without NIS, you may receive less weed control compared to other glyphosate products.

There has been much discussion, research and advertising energy spent comparing glyphosate formulation and material efficacies. As the director of agronomy technical services for an organization that is responsible for the distribution of several different glyphosate formulations applied over a large geographic region, I have seen no efficacy differences among glyphosate materials at the field level. Any research showing different efficacies among glyphosate products has been at the academic or greenhouse level and is probably not applicable to the real world. Environmental conditions present to provide separation among glyphosate materials would limit the effectiveness of all materials and should prohibit application of any herbicide. All glyphosate products have provided targeted weed control greater than 90 percent of the time.

All products have also shown some weaknesses. Most weed control failures associated with glyphosate have been caused by traditionally tough weed species, poor timing (usually weeds have become too large), weed germination after glyphosate application (glyphosate has no residual activity), lower than recommended product application rates or application influenced environmental factors.

My recommendation concerning glyphosate product choice is to make it based upon a combination of past experience, personal preference, manufacturer comfort, manufacturer programs and price.

If you have a weed control failure with glyphosate or any other herbicide material, please evaluate the entire situation to better determine the cause of that lost activity. Glyphosate formulation should be very low on the list of potential causes for those weed control problems.