The planning and preparation growers do before pulling into the field is every bit as important as when they start putting the seed into the ground. Proper Seedbed preparation is required prior to seeding sunflowers whether it’s whether it’s a conventional-till or no-till field.
Starting with clean fields with good chemical control gets plants off to a strong start. Nuseed’s Sunflower Product Development Manager, Alison Pokrzywinski, suggests applying a pre-plant or pre-emergence herbicide in addition to DuPont’s ExpressSun or BASF’s Clearfield production systems.
“The majority of sunflower growers are putting some sort of ‘pre-‘ down, most of them being Spartan, or something from the Spartan Family,” say Pokrzywinski. Spartan, available in the United States, is a Group 14 pre-plant or pre-emergence herbicide with sulfentrazone as the active ingredient.
A Group 15 herbicide with the active ingredient pyroxasulfone has a supplemental sunflower label in the United States. “It’s another tool in the toolbox,” says Pokrzywinski. “Having options helps break up glyphosate use.”
Pre-emergent Herbicides and Effective Modes of Action
According to data from the University of Missouri:
– Some waterhemp populations have evolved resistance to six herbicide classes, including Groups 4, 5, 9, 14, and 27.
– Palmer amaranth has developed resistance to Groups 2, 5, 9 and 27.
– Kochia has developed resistance to Groups 2, 4, 5 and 9 herbicides.
– Marestail, it has developed resistance to Groups 2, 5 and 9.
Bob Weigelt’s, FMC Retail Market Manager, biggest piece of advice is to start mixing and matching different effective modes of action. “In sunflowers, we use Group 1 for grass, Group 2 for broadleaves, and a Group 14 for kocia. Those are the three groups sunflower growers have traditionally used continuously,” says Weigelt.
A variety of new tools exist to fight against these weeds. FMC’s Authority Supreme product combines Group 14 and 15 chemistry and helps to deter the development of resistant weeds, including Group 2, 5 and 9 resistant weeds like pigweed species, kochia and marestail. In sunflower, it can be applied at a use rate of 5.8 to 15.4 ounces per acre, depending on soil type. Make sure to check the label.
The Anthem Flex herbicide from FMC provides residual control of grasses and broadleaf weeds with known resistance to glyphosate and ALS herbicides like waterhemp, Palmer amaranth, and pigweed species. It also suppresses kochia. A sunflower label for this additional Group 15 product is now pending.
“Growers need to do something proactive to head off these problems, especially when it comes to the pigweed invasion that’s coming,” Weigelt adds.
Ken Deibert, Technical Services Manager for BASF based in West Fargo, N.D., says the fight against pigweed is especially concerning and requires new ways of thinking in order to combat it.
Offering both waterhemp and pigweed control, Zidua SC (based on Group 15 chemistry) also suppresses kochia.
BASF’s Beyond herbicide (active ingredient imazamox) is a member of the imidazolinone chemical family. Members of this herbicide family control susceptible weeds by inhibiting the acetohydroxyacid synthase enzyme and are commonly known as AHAS or ALS inhibitors. It may be used with a Clearfield sunflower hybrid to control broadleaf weeds and grasses. At a use rate of 4 fluid oz/acre, it may be applied with an additional grass herbicide if needed.
