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Schmidt: Palmer Amaranth

By Staff | Aug 25, 2017

Last week I had the opportunity to travel to the University of Nebraska Experiment Station at North Platte, NE with a number of my NDSU Extension colleagues as well as a number of industry representatives and Ag media personnel. During our time there we were able to learn firsthand how data collected from the North Platte station’s wind tunnel is incorporated into pesticide labels and also how palmer amaranth is affecting the ag industry and Nebraska Farmers.
Our first day was spent at the North Platte Experiment Station where we toured the Pesticide Application Technology (PAT) laboratory, which is home to two wind tunnels. Research conducted via these wind tunnels provides data for better understanding off target pesticide drift potential with different nozzle types, application pressures, and spray solutions at different wind speeds.
Our group was broken into sub-groups to participate in hands-on nozzle selection exercises to fit a given scenario. Each nozzle was tested, allowing us to see differences in coverage via droplet size and application coverage at differing wind speeds, travel speeds, and spray volume.
The PAT lab also evaluates the effect tank-mixtures has on droplet size as well as how droplet size can be managed for drift mitigation.
The data collected from the wind tunnel in combination with field results could help explain some of the dicamba drift issues being see this growing season across the nation where new dicamba-resistant soybean technology has been implemented.
During Day 1, we also participated in an entomology segment where we visited the station’s entomology lab to learn about insect pests affecting corn and soybean and their research to find parasitic insects to manage these pests. This was followed by a field tour of research being conducted at the North Platte station.
On Day 2, we visited an Ag retailer at Holdrege, NE and toured palmer amaranth affected soybean and corn fields in the area. This part of the trip was breathtaking! It is difficult to find the right words (especially those that can be printed) to describe what we saw in those fields. We definitely DO NOT want this weed here! The weed I am posing with is one of the smaller ones but the stem was easily 4-5 inches in diameter, which will cause some serious challenges at harvest.
As we all know, palmer amaranth – a type of pigweed, is very prone to herbicide resistance (multiple modes of action to date) and grows aggressively. It can grow 2-3 inches per day in optimum conditions, which makes application timing critical. However, like any resistant weed, chemical control cannot be the only method of weed management relied upon.
Since it is likely only a matter of time before palmer amaranth reaches our area, please take time to consider implementing as many of the following strategies as possible to manage herbicide tolerant and resistance weeds now as no single strategy is likely to be totally effective:
* Scout Fields before and soon after herbicide application and manage escapes with effective herbicides or other weed control methods.
* Apply effective PRE herbicides at full rates
* Apply effective POST herbicides that include multiple modes of action in tank-mix or in sequential applications.
* Use full herbicide rates and effective adjuvants
* Spray weeds when they are small. Generally small weeds (<3 inches) are more susceptible to herbicides than large weeds. * Practice Zero Tolerance-- Scout fields after herbicide application and row closure and kill uncontrolled weeds. Mowing, hand weeding and cultivation or tillage may be necessary to accomplish this. * Control weeds in field perimeters, drown out, and non-crop areas * Rotate herbicides with different modes of action in consecutive years * Clean tillage and harvest equipment * Evaluate weed management at the end of each season. Develop a plan for the following year and stick to it. * For more information on palmer amaranth, please visit www.ag.ndsu.edu/NorthCentralREC/weed-science-research/palmer-amaranth-information or contact Yolanda at the Pierce County Extension office by calling 776-6231 ext. 5.

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