Growing non-GMO Soybeans
In 2018, 2019, and 2020, 94% of the U.S. soybean crop acreage was planted to GMO (herbicide resistant–HR) varieties, according to the USDA-ERS. In those years, respectively, 87.6, 74.9, and 82.6 million acres of soybeans were harvested in this country [NASS]; thus, there were 5.26, 4.49, and 4.96 million acres of non-GMO varieties planted in those respective years. According to a USSEC study, the non-GMO acreage had declined to 3.8 million acres in 2022, and this precipitous decline was attributed to current high commodity prices and farmers’ low interest in raising and managing non-GMO soybeans because of less economic value in their doing so. To support this view, the study reports that current non-GMO premiums have not paralleled commodity prices. For example, in 2021, soybean commodity prices increased by about 48%, while premiums for non-GMO soy food beans increased just 4%. The difference in 2022, though smaller, still favored growing GMO beans vs. growing non-GMO and other identity preserved varieties.
Even though U.S. non-GMO soybean acreage is low in relation to the country’s total soybean acreage, there is continued demand for seed harvested from non-GMO varieties. Thus, there likely will continue to be a niche market for non-GMO soybeans for the foreseeable future.
According to results reported in the USSEC study, farmers list weed control as a significant agronomic challenge they face when growing non-GMO soybean varieties. This seems a reasonable concern since non-GMO varieties cannot tolerate in-season, over-the-top applications of glyphosate, 2,4-D, dicamba, and glufosinate that are applied to control problematic weeds in respective HR varieties that are tolerant of these herbicides. That means that weed control in non-GMO varieties will necessarily rely on mechanical cultivation and/or “conventional” herbicides, or herbicides that were available and used before GMO–HR varieties were developed and planted.
The issue of weed control in non-GMO soybean varieties is addressed in a publication titled “Herbicide programs for non-GMO soybeans–CFAES ANR-92” by Dr. Mark Loux of The Ohio State Univ. and Dr. Bill Johnson of Purdue Univ. The basic components of a weed control program for non-GMO soybean varieties follow.
• Choose fields carefully. Pick fields that have been used for crop rotation with effective weed control that has reduced or prevented replenishment of the soil weed seedbank.
• Rotate GMO and non-GMO varieties. A suggested rotation is growing non-GMO soybeans in a field once every 4 years, with two years of corn and one year of an HR soybean variety in between.
• Start weed-free. This likely will involve fall and/or spring tillage coupled with effective fall and spring weed burndown programs.
• Use a broad-spectrum residual PRE herbicide. Use herbicide premixes that contain two or three active ingredients with different modes of aqction that have good activity on targeted problem weeds.
• Supplement these mixtures. For tough-to-control targeted weeds, add an additional amount of an individual component of a premix to equal the full recommended rate for that component had it been applied alone to control a targeted weed species.
• Follow a basic POST program. Apply appropriate POST herbicides when weed escapes are small–i.e. 4-6 in. tall. Use the recommended spray volume and nozzle type that will maximize activity of POST-applied contact herbicides.
• Scout early and often. With early scouting, be on the lookout for problem weeds that have escaped since these may require more than one POST herbicide application to achieve complete control.
• Do not grow non-GMO soybean varieties in fields with tough-to-control weeds that may be resistant to commonly-applied conventional POST herbicides.
In an article titled “Get help understanding herbicide resistance” by Tom Bechman, Dr. Johnson provides pertinent information about weed resistance to Group 2 [ALS inhibitors] and Group 14 [PPO inhibitors] herbicides that can be applied to non-GMO soybean varieties. According to Dr. Johnson, “keeping up with sites of action, chemical group numbers, and weed resistance can be a daunting task”, especially when growing non-GMO soybean varieties. Thus, producers who grow these varieties need to be especially aware of weed resistance development in their fields and choose herbicides accordingly.
Remember, developing and following an effective herbicide program to control weeds in non-GMO soybeans likely will require more management than if growing GMO varieties–i.e. effective herbicide options are fewer and room for error will be decreased.
Composed by Larry G. Heatherly, May 2023, larryh91746@gmail.com