By: Paul Kassel
The question comes up from time to time-‘is there an alternative to the Roundup Ready based seed and herbicide system for soybeans?’ Of course there is-we have conventional varieties with conventional herbicides and there is the Liberty Link seed and Liberty herbicide.
The interest in alternative herbicide/seed system occurs because of glyphosate resistant waterhemp that requires the use of conventional herbicides–like Flexstar, Cobra or Ultra Blazer-with our glyphosate applications. So if we have to use something else beside glyphosate, should we change the whole system?
One seed/herbicide system that can be considered are the Liberty tolerant seed varieties and Liberty herbicide. Part of this interest in Liberty Link occurs because there is no confirmed resistance to the group 10 herbicides. Liberty herbicide is the only Group 10 herbicide we have at this time.
Liberty herbicide is not glyphosate-we have to use a little more management with Liberty herbicide. Label guidelines for application of Liberty recommend 5-inch waterhemp, flat fan nozzles, 40 PSI and 10-20 GPA.
The available varieties and the performance of those varieties is always a big question. If you give up some yield performance, any cost savings and/or herbicide, cost savings is quickly erased.
The Iowa Crop Improvement Association and Iowa State University conduct corn and soybean performance tests. Reports, sortable spreadsheets, and data from individual locations are available here.
The following are some observations from the soybean herbicide traits that illustrate the general performance of these varieties in these tests. This data listed below is general in nature but it does show that the Roundup Ready traited soybean varieties and the Liberty traited varieties perform similar in this test.
Varieties in the north Iowa soybean tests
Bu/a no. in test
Liberty Link 61.5 11
Roundup Ready 1 62.5 7
Roundup Ready 2 Yield 63.0 87
North Iowa test Avg. 62.5 115
Varieties in the central Iowa soybean tests
Bu/a no. in test
Liberty Link 56.0 13
Roundup Ready 1 55.7 11
Roundup Ready 2 Yield 55.7 78
Central Iowa test Avg. 55.5 110