Comparing the Xtend Soybean System to the Roundup Ready System

Background: Federal and international approvals for the Roundup Ready 2 Xtend (Xtend) soybean have allowed in numerous companies to begin selling these varieties this season. Farmers are interested in how these varieties compare with Roundup Ready and/or Roundup Ready 2 Yield soybeans. We intend to investigate the overall system to assess the agronomic performance of the systems. In addition, we will try to assess the genetic effect on relative yield. Roundup Ready 2 Xtend soybeans have been genetically engineered with genes conferring tolerance to both glyphosate and dicamba herbicides. Roundup Ready and Roundup Ready 2 Yield soybeans have been genetically engineered with a gene conferring tolerance to glyphosate herbicide only. To date, two dicamba herbicides have been approved for us in Kentucky on Xtend soybeans (Green 2017). Those two products are XtendiMax and Engenia. These products are different salts of dicamba. Both of these products claim less volatility and drift potential than other formulations of dicamba. Several RR2Xtend soybean varieties were tested in the 2016 Kentucky Soybean Variety Trials (Venard, 2016). The highest]yield RR2Xtend variety ranked 9th, 9th, and 7th in yield for tests the Maturity Group III, IV Early and IV Late tests, respectively. These tests use the same herbicide program for all varieties tested. This test provides evidence of the genetic influence on relative yield. These variety trials do not compare the overall weed control system in conjunction with the genetic traits. Objective: To evaluate relative yield of RR soybean and Xtend soybean in their respective weed management systems.