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South Central Ag Lab Weed Management Field Day

Brandy VanDeWalle

Those interested in learning the latest in weed management technologies and herbicides for weed control in corn, soybeans and sorghum are invited to attend Nebraska Extension Weed Management Field Day to be held on Wednesday June 26, 2024 from 9 am to 1 pm at South Central Ag Lab near Clay Center, NE. The Field Day is free to attend and lunch; UNL Dairy Store Ice cream will be provided. Register is required at https://agronomy.unl.edu/fieldday.

Tour one features onsite demonstrations of new technology/herbicides for weed control in soybeans in sorghum such as:

  • Planting Green and Residual Herbicide Interaction in soybean: Planting green refers to no-till planting of the primary crop into actively growing cover crop. Cereal rye is the most planted cover crop in corn/soybean cropping systems in Nebraska. The objectives of this project are (1) To evaluate effect of planting green on performance of residual herbicides applied pre-emergence for weed control in soybean, and (2) Effect of early termination of cereal rye versus planting green on weed control and soybean yield.
  • Inter-seeding Small Grains (Barley, Oat, and Wheat) in Soybean for Weed Suppression: Evaluate the effect of inter-seeding small grains into soybean on weed suppression and soybean yield and grain quality.
  • Comparison of Herbicide Programs for Weed Control in Soybean: Unbiased comparison of herbicide programs of different companies for weed control in Roundup Ready 2 Xtend and Enlist soybean. New herbicides and multiple herbicide-resistant soybean will be discussed for management of herbicide-resistant weeds.
  • Evaluating Residual Herbicides for Overlapping Residual Weed Control in Soybean: Can we achieve season-long weed control in soybean by using residual herbicides applied pre-emergence and post-emergence without a foliar active herbicide? This project will discuss the possibility of complete residual weed control in soybean.

Tour two features onsite demonstrations of new technology/herbicides for weed control in corn such as:

  • Comparison of Herbicide Programs for Weed Control in Corn: Unbiased comparison of herbicide programs by different companies for weed control in Roundup Ready/LibertyLink corn. New herbicides in corn will be discussed.
  • Control of Corn Volunteers in Enlist Corn: Volunteer corn is a major weed in corn-soybean cropping systems. Project will demonstrate how to control volunteer corn in Enlist corn using Assure II and a premix of glufosinate (Liberty) + quizalofop (Assure II).
  • Evaluating Surtain (saflufenacil + pyroxasulfone) for weed control and crop safety in corn & popcorn: Surtain is the new Kixor herbicide based on solid-encapsulation technology, enabling pre- and early-post-emergence application for weed control in corn.
  • Control of Corn Volunteers in iGrowth and Double Team Sorghum: When sorghum is planted after corn, corn volunteer is a major weed. iGrowth sorghum is a new herbicide-resistant sorghum that provides an opportunity for post-emergence control of grass weeds, including corn volunteers. ImiFlex (imazamox) and Zest (quizalofop) will be evaluated for control of volunteer corn.
Crops, Horticulture

2,4-D Amine vs. Ester Formulations

Brandy VanDeWalle

The other day I got a question from a client regarding the different formulations of 2,4-D, a very common herbicide used widely by gardeners and farmers. I found a great fact sheet from Purdue University which described the differences and is summarized below. It starts out by saying that the amine and ester of 2,4-D are both formulations of one of the oldest and widely used herbicide families, as they were developed in the mid-1940’s by the military for vegetation control. It works as a growth regulator herbicide which induces unorganized growth in the plant which can therefore crush the vascular system of the plant, blocking it off from nutrients, sugar and water.

Used to control annual, biennial, and perennial broadleaf weeds, 2,4-D has little effect on grasses, thus making it the most popular herbicide used in lawns. While it is effective if applied at the correct time, drift can easily occur in non-targeted broadleaf plants due to the result of 2,4-D volatility, its ability to turn into a vapor and move off site. This is how the amine and ester formulations can differ.

Purdue’s publication goes on to summarize that the ester formulation of 2,4-D have higher vapor pressures and tend to volatilize more than amines, therefore one should use an amine formulation when volatilization is a concern with sensitive plants. I always caution people who use 2,4-D that volatility increases in hot, dry weather. When temperatures are above 85 degrees F, only the amine formulations should be used. Ester formulation is more effective at penetrating the leaf cuticle, so amine use rates are usually higher than ester rates to compensate for reduced absorption.

WeedGuide

One weed I’ve been receiving several questions on is the purple flower growing in lawns – most likely henbit. It definitely flourished with last year’s drought, but for best control, apply a broadleaf herbicide in the fall. To achieve 90% control of henbit, apply a post emergent herbicide such as Trimec when in the early growth stage. There are several formulations of Trimec which uses 2,4-D as an active ingredient.

In summary, know which formulation you are working with, apply during the most effective time for your target species and adjust rates accordingly. As always, follow label directions and take the proper safety precautions to protect your health. For more helpful information on which herbicides to apply and when, go to UNL Extension’s Weed Guide.