AMES — Controlling weeds in farm fields is an annual challenge – especially with more weeds becoming resistant to herbicides.
Fortunately, producers have a wide range of options to counter weeds, including some creative ways that may not have been employed in the past.
At this year’s Farm Progress Show, Aug. 30-Sept. 1 in Boone, Iowa State University Extension and Outreach will showcase one of the more innovative, and practical methods of controlling weeds: a weed seed destructor.
Fitted to a combine, the weed seed destructor does what its name implies. It pulverizes and destroys seeds so that they cannot germinate.
The weed seed destructor (by Redekop) will be attached to the back of a John Deere 680 combine and will be available for viewing outside the ISU Extension and Outreach tent. While the machine will not be operating during the show, visitors can see it in operation on a computer screen, and they can ask questions of weed science experts.
“We want to give the public a chance to see and ask about this innovative form of weed control technology,” said Prashant Jha, professor and extension weed specialist at Iowa State. “Farmers in central Iowa and in Harrison County are already using this technology and we expect more will do so in the coming years.”
Other methods of weed control will also be featured, including videos of chaff lining, a method that guides the harvested chaff into narrow bands as it flows out the back of the combine at harvest, which reduces the spread of weed seeds by more than 95% across the fields and contains weed seeds in smaller spaces.
The harvester or combine is modified with a baffle that separates the chaff (containing the majority of weed seeds) from the straw. The chaff is directed into narrow central bands using a chute at the rear of the combine.
Weed seeds in the chaff are subjected to decay, and burial of small-seeded weed species such as waterhemp in the chaff will potentially result in reduced emergence in the subsequent growing season. High application rates of herbicides or shielded sprayers can be used to selectively control emerged weeds in those narrow bands in the field.
The weed control display will also allow visitors the chance to test their knowledge of weed specimens found in the Midwest. Sixteen different species will be available for visitors to identify.
Visitors will also have the chance to learn more about waterhemp, and how it can be suppressed using cereal rye as a cover crop. Photos and sample trays will show the results of using no rye, rye terminated at 4-6 inches tall, and rye terminated close to heading.
“We’re going to be showing the potential for biomass (cover crops) to suppress weeds like waterhemp, and how the results vary based on the height of the cover crop,” said Jha.
Cereal rye has the best potential to suppress weeds because it accumulates more biomass than other cover crop species. A study that was done for the Farm Progress Show shows an incremental decrease in waterhemp based on the density of rye.
Field studies indicate cereal rye biomass of 4,500 to 5,000 pounds per acre at termination can significantly suppress waterhemp emergence in soybeans and reduce the size and density of waterhemp at the time of exposure to postemergence herbicides.
Additionally, producers can view a map of where herbicide resistance has been documented in Iowa based on the recent survey and ask questions to Jha and other specialists about their own experience with herbicide-resistant weeds.
Jha will be joined at the show by ISU Extension and Outreach field agronomists Angie Rieck-Hintz, Meaghan Anderson, Gentry Sorenson and Mike Witt and several weed science graduate students.