On November 9, 2016, the USEPA approved the use of XtendiMax with VaporGrip Technology starting in 2017 on Roundup Ready 2 Xtend Soybeans. This is a new formulation of dicamba herbicide that promises to have low volatility. A new tool to combat the tough to control weeds, such as tall waterhemp and palmer amaranth. Its herbicide site of action is Synthetic Auxins, Group 4.
READ THE LABEL!!! This product has a very restrictive label with wide set-back areas; wind speed restrictions; low weed height restrictions; maximum and minimum use rates; and the specific nozzle to be used.
XtendiMax be used on weeds no taller than 4 inches in post-emergence applications. In fact, the label states "Monsanto Company does not warrant product performance of applications to labeled weeds greater than 4 inches in height." The minimum use is 22 fluid ounces (0.5 lb a.e. dicamba) per acre and the maximum use is 22 fluid ounces (0.5 lb a.e. dicamba) per acre for post-emergence applications.
Since dicamba herbicide can cause crop damage to sensitive crops, the label requires the use of "only Tee Jet® TTI11004 nozzle with a maximum operating pressure of 63 psi when applying XtendiMaxTM With VaporGripTM Technology or any other approved nozzle found at www.xtendimaxapplicationrequirements.com. Do not use any other nozzle and pressure combination not specifically listed on this website." The sprayer boom is not to exceed a boom height of 24 inches above target pest or crop canopy.
There is a wind speed table that shows the allowable wind speeds and their directions for applying this product. In addition, "maintain a 110-foot downwind buffer (when applying 22 fluid ounces of this product per acre, post-emergence rate) between the last treated row and the closest downwind edge of sensitive areas (in the direction in which the wind is blowing)."
Before making an application, applicators are required to survey the neighboring areas for non-target sensitive crops and to check sensitive crop registries, such as Illinois DriftWatch, to identify specialty crop and certified organic fields. The label makes it very clear that it is the applicator that is responsible for herbicide drift, "AVOIDING SPRAY DRIFT AT THE APPLICATION SITE IS THE RESPONSIBILITY OF THE APPLICATOR."
As with any growth regulator type of herbicide, sprayer system cleanout is extremely important to avoid injury to non-dicamba-tolerant crops as are planting restrictions for certain crops.
The XtendiMax technology will be a new tool for farmers in their battle to control weeds, however good herbicide stewardship needs to be practiced. Remember to rotate herbicide sites of action, use several weed control strategies – cultivation, cover crops and crop rotation, sequential herbicide applications with alternate sites of action, and clean plant residue off of harvest equipment when moving between fields.
Remember here in Illinois, we have already identified a tall waterhemp population that is resistant to the Synthetic Auxins (Group 4) herbicide site of action. That is right, we already have weeds present in our state that are resistant to XtendiMax's herbicide site of action, so please use this product responsibly.