Preemergence herbicide programs for corn
* ALS-inhibitors. Examples of ALS-inhibitors for use as a soil-applied herbicide for corn include flumetsulam (Python) and Hornet, which is a premix of flumetsulam and clopyralid. Both herbicides have broadleaf activity only. These products are strong on large-seeded broadleaf weeds such as cocklebur, sunflower, and velvetleaf, or the small-seeded common lambsquarters. Adding Hornet to a full rate of an acetamide/atrazine mix as a preemerge treatment will control the annual grasses and add considerably to large-seeded broadleaf weed control. Sunflower appears to be most sensitive to Hornet, followed closely by cocklebur and velvetleaf. Morningglory is less sensitive. Depending on weed species present, control may be improved enough that a postemerge treatment is not needed.
An additional ALS-inhibiting herbicide from DuPont is called Resolve. Also a component in Prequel, which was previously mentioned, Resolve will provide short residual control of grass and broadleaf weeds and should be used as a setup herbicide with a good postemergence weed control program. If ALS-resistant broadleaf weeds are present, these ALS-containing herbicides often will be less effective.
New products for 2013
There are four new herbicides containing Pyroxasulfone labeled for corn in 2013.
* Zidua, from BASF, contains the new active ingredient pyroxasulfone, which is in the acetamide family. Pyroxasulfone provides excellent residual control of annual grasses, with minor activity on shattercane, excellent activity on pigweeds, and good activity on velvetleaf and kochia. Pyroxasulfone has better activity on kochia than other acetamides. When combined with atrazine, this product will be very competitive with other acetamide/atrazine premixes.
* Fierce is a premix of the new active ingredient pyroxasulfone and Valor. This Valent product, because of the Valor component, must be applied to corn at a single use rate of 3 oz/acre at least 7 days before planting. The Valor component in Fierce will provide improved activity on some broadleaf weeds over Zidua alone.
* Anthem, from FMC, is a premix of pyroxasulfone and Cadet. This product will give similar residual weed control as Zidua. However, Anthem will provide some activity on limited broadleaf weed species when applied postemergence.
*Anthem ATZ is a premix of Anthem plus atrazine. The addition of atrazine will enhance broadleaf weed control, especially for kochia, and the large-seeded broadleaf weeds like velvetleaf and morningglory.
The rate structure of Zidua, Anthem, and Anthem ATZ is dependent upon soil texture. Coarse, medium, and fine textured soils allow different rates of these herbicides. Also, these herbicides can be applied on corn up to V4 stage of growth. Product availability of these new herbicides may be limited in 2013.