Grain sorghum producers should soon have a new option for postemergence control of certain annual grass weeds. Several seed companies are developing hybrids of a new type of herbicide-resistant grain sorghum called Inzen-Z sorghum. DuPont Pioneer holds the rights to this new technology, but other seed companies have licensed the right from DuPont to develop these new hybrids as well. The “Z” stands for Zest, the proposed name of a new herbicide from DuPont Crop Protection that will be used in the Inzen-Z sorghum system.
Zest has not yet received approval for use by the U.S. Environmental Protection Agency. That is the final step in the approval process. If Zest receives EPA approval, a small amount of Inzen-Z grain sorghum hybrid seed could be on the market as early as next season, 2015.
The active ingredient in Zest is a new liquid formulation of nicsulfuron, which is also the active ingredient in Accent herbicide used primarily to control non-ALS-resistant shattercane and other annual grasses in corn. Zest is a postemergence grass herbicide.
In grain sorghum, it can control non-ALS-resistant populations of shattercane, volunteer sorghum, volunteer wheat, witchgrass, barnyardgrass, the foxtails, and small-sized crabgrass. Zest may provide poor control of grassy sandbur and stinkgrass unless these grasses are very small at the time of application. Once registered, a complete list of grasses controlled will be provided in the Zest label.
Producers will need to tank mix another herbicide with Zest to get postemergence broadleaf control with a single application. Possible tankmix options include atrazine, dicamba, 2,4-D, and Huskie. Atrazine may antagonize crabgrass control.
One thing producers should be aware of when using this new grain sorghum system is that certain Inzen-Z hybrids are a little yellowish at the time of emergence. These hybrids will grow out of it and appear normal later in the season. Also, the application of Zest herbicide may cause some temporary yellowing to the Inzen-Z hybrids (and by the way, this herbicide will kill non-Inzen-Z hybrids). There is no stunting of the Inzen-Z hybrids from Zest, however, and the temporary chlorosis appears to be cosmetic.
Curtis Thompson, Extension Agronomy State Leader and Weed Management Specialist
cthompso@ksu.edu
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