Herbicide Resistance – 7 Steps With Something New To Consider – AgFax Weed Solutions

Here is this month’s issue of AgFax Weed Solutions, sponsored by Nufarm’s Midwestern and Southern teams.
Editor: Owen Taylor
Web Editor: Ernst Undesser

Coverage This Month Includes:

States: Alabama, Iowa, Louisiana, Michigan, Minnesota, Nebraska, Tennessee.

Topics: Herbicide resistance management, state-level dicamba policy, problems caused by herbicide antagonism, spring weed control issues.

Okay, you’ve seen plenty of lists that suggest ways to prevent or cope with herbicide resistance. This one is different. It starts with the way the wrong tank-mix combinations can make resistance worse, much worse.
Injury complaints skyrocketed in the soybean-heavy states of Indiana and Illinois in 2019. A regulatory group also requested EPA make any future registration of these herbicides “conditional on a year-by-year basis.”
Warmer temperatures and adequate moisture have set the stage for rapid weed growth in the coming weeks. Since very few weeds were present at the time of pre-plant tillage this year, timely and effective herbicide applications must do the heavy lifting in most weed management programs.
Italian ryegrass has exploded in Louisiana on a huge scale. “Honestly, this is not surprising because we have not been addressing this pest properly.”

“If we don’t control weeds prior to planting, these weeds continue to grow, and they can be harder to control later. This is especially a problem with glyphosate- and ALS-resistant horseweed (marestail).”
Controlling junglerice with a post-emerge program is far from foolproof, based on plenty of failures reported in the last two years. Research now points to herbicide antagonism and coverage issues.
Planting started early in parts of the state and preemerge herbicides went out ahead of rains that perhaps didn’t fall soon enough. Will the herbicides still work? Here’s an overview on possible outcomes and suggestions on post-emerge approaches.
Researchers looked at both Xtend and Enlist, and results varied by technology and season. “This is a reminder for growers who hold unrealistic expectations that new technology will always bail them out.”

Gaining effective control following seasons with heavy weed escapes will both preserve short-term yield and have long lasting effects by diminishing the weed seedbank.
Palmer now packs enough resistance and cross resistance that a pre-emerge package by itself won’t be enough on an increasing number of soybean acres. Here are options.
Crops made a fast start this year and so did weeds. This will be a season to focus on layered preemerge herbicide strategies and the potential to put new technologies to the test.
Plenty of late-spring frosts have singed crops and weeds, raising questions – is it safe to spray the crop and will herbicides actually work on frost-damaged weeds?

3 Key Reports You Might Have Missed
In a couple of states, researchers are seeing slippage when dicamba is applied to certain Palmer amaranth populations. These survivors turn up in tightly controlled comparisons, not random field observations. Consider these findings a wakeup call that is ringing very faintly at the moment – yet we can’t afford to ignore it.
In Australia, new methods of weed control have evolved, and a group of American scientists toured the country’s ag production areas to see these systems in action. They came away with ideas about what might work now and which approaches deserve further evaluations.
Cotton prices plummeted with the onset of the pandemic, putting them at or below the cost of production. Looking for ways to survive, some growers are thinking about a “dirt cheap” way to manage this crop. But with prospects for sloppy pigweed control, can you afford to cut corners?


AgFax Weed Solutions is published by AgFax Media LLC. If you’re receiving this newsletter from us, either a friend or business contact asked us to forward the report to you or you are a regular subscriber to one of our crop, pest and issue-related reports covering states in the Corn Belt, South, Southwest and Far West.

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Questions? Contact Owen Taylor, 601-992-9488

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