Several new herbicides have been registered for weed control in corn. These new herbicides do not have an active ingredient with a new mode of action, but they are tank mixtures of existing herbicides. Here is the list of corn herbicides expected to be available in the 2015 growing season. 

Anthem™ ATZ [atrazine (42.5%) + pyroxasulfone (5.15%) + fluthiacet-methyl (0.15%)]. It is a premix of three herbicides with different modes of action. It can be applied pre-plant, pre-emergence, or early post-emergence for control of broadleaf and grass weeds in all types of corn. Do not apply more than 39 oz/ac per growing season in coarse-textured soil and do not apply more than 76.46 oz/ac in medium- and fine-textured soils. Do not harvest or feed grain or stover within 70 days of last application. EPA Reg. No. 279-3449. Mode of action groups: 5, 15, 14.

Breakfree® NXT ATZ [acetochlor (33.4%) + atrazine (26.9%)]. It is a premix for pre-plant and pre-emergence control of selected broadleaf and grass weeds in corn. The application rate ranges from 1.4 to 3 quarts/ac depending on soil texture and organic matter content. EPA Reg. No. 62719-671-352. Breakfree® NXT Lite [acetochlor (46.3%) + atrazine (18.3%)]. This herbicide is similar to Breakfree® NXT ATZ, but contains more acetochlor and less atrazine. EPA Reg. No. 62719-670-352. Mode of action groups: 15, 5.

Callisto® GT [glyphosate (34%) + mesotrione (3.4%)]. It is a new premix for post-emergence weed control in glyphosate-resistant (Roundup Ready) corn. Do not apply more than one time per year and do not apply more than 2 pints/ac per year. Do not harvest forage, grain or stover within 45 days after application. EPA Reg. No. 100-1470. Mode of action groups: 9, 27.

DiFlexx™ [dicamba (56.6%)]. It may be used pre-emergence or post-emergence for control of annual broadleaf weeds and control or suppression of many biennial and perennial broadleaf weeds in field corn, field corn grown for silage, white corn, seed corn, and fallow cropland. DiFlexx includes exclusive CSI™ Safener technology which enables plants to better withstand herbicidal activity and provides better crop safety. Additionally, the safener in DiFlexx will safen the use of any amide product used before crop emergence. It can be applied from burndown or pre-plant as far out as 30 days prior to planting through late post-emergence (V10) at a rate of 8 to 16 fl oz/ac. It can be applied sequentially or in tank mixtures to provide a complete weed control program in corn. Do not exceed application rate of 64 fl oz/ac per year. Mode of action groups: 4.

Fierce™ [flumioxazin (33.5%) + pyroxasulfone (42.5%)]. Fierce is a new premix for pre-emergence control of broadleaf and grass weeds in no-till and minimum till corn. Mode of action: flumioxazin is a PPO inhibitor and pyroxasulfone is a seedling growth inhibitor.  EPA Reg. No. 63588-93-59639. Mode of action groups: 14, 15.

Instigate™ [rimsulfuron (4.17%) + mesotrione (41.67%)]. Instigate is a new premix for pre-plant and pre-emergence control of broadleaf and grass weeds in corn. It can be applied up to 14 days prior to planting or before corn emergence. It can be applied within a rate range of 5.25 to 7 oz/ac, depending on soil texture. EPA Reg. No. 352-873. Mode of action groups: 2, 27.

Solstice™ [fluthiacet methyl (2.2%) + mesotrione (38.52%)]. It contains two active ingredients possessing both contact and systemic activity that can be applied post-emergence for selective control of broadleaf weeds in field corn, seed corn, yellow popcorn, and sweet corn. It can be applied up to V8 corn growth stage or until corn is 30 inches tall. Application rate is 2.5 to 3.15 fl oz/ac. If atrazine is mixed with Solstice, do not apply to corn that is more than 12 inches high. EPA Reg No. 279-3461. Mode of action groups: 14, 27.

Zemax™ [S-metolachlor (36.8%) + mesotrione (3.68%)]. Zemax contains the active ingredients of Callisto (mesotrione) and Dual II Magnum (S-metolachlor). This double-mode-of-action herbicide can be applied from 14 days early pre-plant up to 30-inch corn. Zemax is also used in grain sorghum for pre-emergence control of many annual grass and broadleaf weeds. EPA Reg. No. 100-1410. Mode of action groups: 15, 27.

Zidua™ [pyroxasulfone (85%)]. Zidua is a pre-emergence herbicide for control of annual grasses and some small-seeded broadleaf weeds in corn. It is also labeled for early post-emergence application in corn, but only has residual activity. Therefore, when applied post-emergence in corn it should be tank-mixed with another foliar active herbicide for control of existing weeds and Zidua will provide residual activity. Application rates of Zidua vary depending on soil texture. EPA Reg. No. 7969-338. Mode of action group: 15.

More information about the efficacy of these and other herbicides is available in the 2015 Guide for Weed Management in Nebraska (EC130) for sale in a print or downloadable version from at http://marketplace.unl.edu/extension/extpubs/ec130.html

Always refer to the herbicide product label for complete details and directions for use.

Amit Jhala
Extension Weed Management Specialist
Stevan Knezevic
Integrated Weed Management Specialist