Current status of new herbicide-resistant crops
Producers, in the near future, will have access to several new crop cultivars with resistance to a wider range of herbicides than has been available until now. Here is a quick summary of these new crops and when they are expected to reach the market.
Inzen Z grain sorghum. K-State released to sorghum breeding programs a line of grain sorghum that is resistant to ALS herbicides several years ago. DuPont assumed ownership of the technology and those seed companies that signed agreements with DuPont will be developing Inzen Z sorghum hybrids. DuPont also is developing the ALS grass herbicide “Zest,” with nicosulfuron as the active ingredient, for use with these new ALS-resistant grain sorghum hybrids. DuPont will brand name the sorghum “Inzen Z sorghum.” When commercial Inzen Z hybrids are on the market producers will have new opportunities for postemergence grass weed control. DuPont intends to have herbicide registration for Zest completed in time for use on the 2016 sorghum crop.
Enlist corn, soybeans, and cotton. Enlist traits are being developed by Dow AgroSciences. These traits confer resistance to both 2,4-D and aryloxyfenoxypropionate (the “fop” grass herbicides) in corn, and 2,4-D resistance in soybeans and cotton. Dow has developed a new formulation of 2,4-D called 2,4-D choline, which is lower in volatility than 2,4-D amine. This new formulation will be marketed in a premix with glyphosate called Enlist Duo. This premix will be intended for use on Enlist crops, and has just received a full Section 3 Federal label.
Enlist soybean and corn traits have been deregulated by the U.S. Department of Agriculture. However, certain export markets have not been approved yet, so commercial availability is not yet known. Enlist corn and soybeans could potentially be available for the 2015 growing season and cotton in 2016. Enlist soybeans and cotton could alleviate concerns about herbicide drift onto the crop from adjacent applications of 2,4-D. Enlist soybeans will be stacked with both glyphosate- and glufosinate-resistant genes as well, which would also allow the use of glyphosate and Liberty herbicides on those crops.
Xtend soybeans and cotton. Xtend traits are being developed by Monsanto Company. These traits confer resistance to dicamba herbicide. This would allow direct application of new formulations of dicamba to soybeans and cotton to help address glyphosate-resistant weeds, as well as alleviate concerns about dicamba drift onto Xtend crops. BASF and Monsanto are developing new formulations of dicamba with lower volatility and drift potential than Clarity, which already has lower volatility than Banvel. Monsanto will sell a premix of glyphosate and a new formulation of dicamba under the product name of Roundup Xtend. A new dicamba formulation will also be available by itself under the product name of XtendiMax for Monsanto and Engenia from BASF. Xtend crop technologies are still under review in the regulatory process, and probably won’t be available before 2016.
Note: Dicamba- and 2,4-D-resistant soybeans and cotton are not cross-resistant, so application of dicamba on Enlist crops or 2,4-D on Xtend crops would still result in severe injury or plant death. As mentioned above, new formulations of dicamba and 2,4-D are being developed with reduced volatility, but spray drift will still be a concern onto susceptible or non-resistant crops.
HPPD-resistant soybeans. GMO soybeans with resistance to the HPPD-inhibiting class of herbicides are in development by both Bayer and Syngenta. No HPPD herbicides are currently available for use in soybeans, so this would provide a new mode of action and allow for greater diversification of weed control options to help manage herbicide resistant weeds. HPPD-resistant soybeans and matching herbicides still need regulatory approval, so will not be available until 2016 at the earliest.
Dallas Peterson, Weed Management Specialist
Curtis Thompson, Weed Management Specialist and Extension Agronomy State Leader