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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.

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Keep an Eye out for Asian Copperleaf

September 28, 2023
Map of currently known Asian copperleaf infestations in Iowa, September 2023.

With yet another sighting of Asian copperleaf (Acalypha australis) this fall, it’s a good reminder to keep an eye out for this new species during harvest. Asian copperleaf (Acalypha australis) was first discovered in Iowa in 2016 in a corn field near Cedar Falls. Prior to this discovery, the only documented infestation in North America was within New York City. Since the initial discovery, it has been found in four other locations, totaling five counties across north central Iowa (Figure 1).

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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.

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A New Palmer Amaranth Find Underscores Importance of Scouting

August 16, 2023
Palmer amaranth leaf with a petiole longer than the leaf blade. Folding the leaf over at the base is the fastest way to check for this trait.

This is a great time of year to scout for Palmer amaranth (Amaranthus palmeri) in Iowa crop fields. While Palmer amaranth has been identified in more than half of Iowa’s counties, new identifications have slowed since the widespread introductions on non-crop acres in 2016. A new Palmer amaranth introduction was recently identified in a crop field in central Iowa, highlighting the importance for farmers and agribusiness professionals to remain vigilant in scouting for this species.

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PIDC Dos and Don'ts - Field Crops Edition

June 15, 2023 9:50 AM
Blog Post

We’re well into the growing season in Iowa. We are in full swing in the Plant & Insect Diagnostic Clinic (PIDC) as growers, certified crop consultants, and field agronomists start to notice problems in their fields. While there is information on our PIDC webpage (https://hortnews.extension.iastate.edu/pidc) about the services that we provide, with some sample snafus this spring, I figured it was time to write a brief blog article to remind you here, too.

Spring Management of Multiflora Rose

June 1, 2023 3:02 PM
Blog Post

With the steady growth and production of pasture forages across the state comes the steady appearance and growth of the nuisance pasture weed, multiflora rose (MFR). Due to its unpalatability, most grazing species will not consume MFR, allowing it to continue growing throughout the season and outcompete other forage species and remain persistent.

Multiflora rose bush

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Look before you leap: Cautions for delayed preemergence applications in soybean

May 7, 2023 9:48 PM
Blog Post

The beautiful weather this past week means we’ll see a substantial increase in planted acres on this week’s Crop Progress and Condition Report. Farmers should carefully evaluate their herbicide choices before spraying any planted soybean fields that didn’t get their preemergence (PRE) herbicide on ahead of the rain over the weekend. It is always important to read and follow the label – it’s the law after all.

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