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Suspected 2,4-D Resistant Waterhemp Population Discovered

February 13, 2024

We know the evolution of resistance in waterhemp populations happens faster than new herbicides are discovered, so the recent report of dicamba resistant waterhemp in Iowa by Bayer was not unexpected. Corteva has now reported the discovery of a suspected 2,4-D resistant waterhemp population in Iowa.

Crops: 

Dicamba-resistant Waterhemp in Iowa

September 5, 2023

While the registration of 2,4-D and dicamba products for over-the-top use in resistant-varieties has improved waterhemp control for many farmers, weed scientists warned that these herbicides would eventually select for resistant waterhemp populations. Bayer recently reported the discovery of two likely dicamba-resistant waterhemp populations in Iowa, which warrants a discussion on best management practices to slow the evolution of resistant waterhemp populations.

Crops: 

New cut-off date for over-the-top dicamba use in Iowa for 2023

February 22, 2023 2:08 PM
Blog Post

On February 16, the U.S. Environmental Protection Agency (EPA) approved the label amendments that further restrict the use of over-the-top (OTT) dicamba in Iowa, Illinois, and Indiana. For the 2023 season, the revised federal labels for XtendiMax, Engenia and Tavium contains a new cut-off date restriction for OTT dicamba use:

Don’t Let the Pigweeds Produce Seed

July 29, 2022 7:16 PM
Blog Post

This is the time of the year when late-season pigweeds (waterhemp and Palmer amaranth) poke through the soybean canopy and produce seeds. These late-season pigweeds either emerged after herbicide applications, or survived inappropriately timed or less-than-effective postemergence herbicides. Given waterhemp and Palmer amaranth’s propensity to evolve resistance to herbicides, it is also possible that the survivors are resistant to the postemergence herbicide that was used.

Pay attention to crop size restrictions on herbicide labels!

June 7, 2022 9:26 AM
Blog Post

Postemergence herbicide application season is already upon us in much of Iowa, but with the delayed crop planting in some areas, it may extend through much of the month of June. Herbicide application timing should always focus on the sizes of weeds targeted but remember that many products use crop growth stage and calendar date as application restrictions.

2022 ISU Weed Science Field Day is on July 14

May 26, 2022 10:01 AM
Blog Post

This year’s Weed Science Field Day will be held on Thursday, July 14 at the Iowa State University Curtiss Farm, Ames, IA.

Although the 2022 cold and wet spring has significantly delayed corn and soybean planting in Iowa, we are still on track to demonstrate corn and soybean research plots on the Field Day.

The Field Day will include an update on corn and soybean herbicide programs, status of herbicide resistance in waterhemp in Iowa, cereal rye cover crop for weed control, and demonstrations of novel harvest weed control methods including chaff lining and seed destructor.

In the Mad Rush, Don't Forget Your Herbicide!

May 6, 2022 2:18 PM
Blog Post

This spring's weather has resulted in an unusually slow start to the growing season, especially when compared with the past two years. In springs like these, field operations are condensed and there may be temptation to skip some of the field preparation to get acres planted in a timely manner. This article will address considerations for herbicide applications in these situations.

Coping with Herbicide Shortages in 2022: Adding More Tools in the Toolbox

March 7, 2022 6:02 PM
Blog Post

Shortage of key herbicides, glyphosate and glufosinate, in 2022 has emphasized the need to implement integrated weed management (IWM) strategies in corn and soybean. It is time to consider adding more tools in the weed control toolbox. In the previous blog post, we discussed alternative herbicide programs (Tool# 1) available for weed control in 2022 to stretch glyphosate and glufosinate over more acres. In this article, we will discuss other weed control tactics (cultural and mechanical strategies) to plan for 2022 and beyond.

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