Nebraska: Top Weed Problems and Most Common Herbicides

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Stakeholders across Nebraska were surveyed during Nebraska Extension meetings about their top weed management issues. The survey was conducted at seven locations (Atkinson, Norfolk, Gering, Beatrice, Hastings, Kearney and North Platte) representing the four extension districts (Figure 1) in 2015.

A total of 425 responses (growers: 151, crop consultants: 113, and others: 161) were represented in the final survey report. Stakeholders were asked questions on four topics:

  1. Crop Production and Problem Weeds
  2. Herbicide Use
  3. Glyphosate-Resistant Weed Management
  4. Weed Management Research and Extension Priorities

Crop Production and Problem Weeds

Survey results showed that corn and soybean were the major crops in Nebraska. Less than 20% of the total area was planted with alfalfa, dry edible bean, grain sorghum, hay, proso millet, sugarbeet, and wheat. The greatest crop diversity was in the Panhandle district.

In Nebraska the most problematic weeds were common waterhemp, marestail, and kochia, followed by velvetleaf, common lambsquarters, Palmer amaranth, and giant ragweed.

Nebraska Extension districts and survey sites
Figure 1. Nebraska Extension districts and sites where surveys were conducted. Click Image to Enlarge

Respondent Profile

  • 61% of total farmed or scouted cropland was in no-till production
  • 82% of total farmed or scouted cropland was in corn and soybean production
  • 60% of the growers reported having at least one glyphosate-resistant weed on their farm
  • 34% of growers rotated glyphosate-resistant crops with non-glyphosate-resistant crops
Table 1. The top five problem weeds by Nebraska reporting district, based on a 2015 statewide survey.
Rank Northeast Panhandle Southeast West Central
1 Common waterhemp Kochia Common waterhemp Kochia
2 Marestail Common lambsquarters Marestail Common waterhemp
3 Velvetleaf Field bindweed Kochia Marestail
4 Kochia Palmer amaranth Velvetleaf Palmer amaranth
5 Giant ragweed Canada thistle Common lambsquarters Foxtails

The majority of growers and crop consultants who responded were concerned about the evolution and spread of the ALS inhibitor-resistant (for example, Classic, Pursuit, and Sceptor) and glyphosate-resistant weeds, such as common waterhemp, marestail, kochia, Palmer amaranth, and giant ragweed. In this survey, 40%, 26%, 23%, and 11% of growers reported having no, one, two, and three or more glyphosate-resistant weed species, respectively, on their farm.

Herbicide Use

Respondents indicated that residual herbicides applied pre-emergence followed by post-emergence application of glyphosate tank-mixed with other herbicides was the most effective weed management option (Figure 2).

Of the growers, 72% indicated using at least one pre-plant burndown herbicide in the spring. Glyphosate, 2,4-D, and Sharpen (saflufenacil) were the most commonly used pre-plant burndown herbicides listed in the survey.

Chart of pre-emergence herbicide use in corn and soybean, 2015 survey.
Figure 2. Survey respondents indicated use of pre-emergence herbicide was higher in corn compared to soybean. Click Image to Enlarge
Table 2. The top three most commonly used pre-emergence herbicides in field corn, soybean, and grain sorghum, based on a 2015 statewide survey.
Rank Field Corn Soybean Grain Sorghum
1 Lexar EZ/Lumax EZ Authority First/Sonic Bicep II Magnum
2 Corvus Valor/Valor XLT Lexar/Lumax
3 Degree Xtra/Harness Xtra / Keystone NXT Enlite/Envive Atrazine

The majority of corn and soybean acres were treated with glyphosate. Select Max was also listed among the most commonly used soybean post-emergence herbicides to control volunteer corn and other grass weeds.

Table 3. The top three most commonly used post-emergence herbicides in field corn, soybean, grain sorghum, and wheat, based on a 2015 survey.
Rank Field Corn Soybean Grain Sorghum Wheat
1 Glyphosate Glyphosate 2,4-D 2,4-D
2 Halex GT Cadet Dicamba Ally XP
3 Status Select Max and Cobra Huskie and Permit Amber/Rave

Glyphosate-Resistant Weed Management

Growers and crop consultants reported that their average weed management cost in corn and soybean were $36 and $33 per acre, respectively. Cost of weed management for sugarbeet, which was only reported from the Panhandle District, was $43 per acre.

In this statewide survey, 80% of the respondents expressed their concerns regarding the volatility/physical drift of 2,4-D and dicamba following the commercialization of new crop technologies (Roundup Ready 2 Xtend and Enlist). However, misapplication of the herbicides, temperature inversion, tank contamination, and evolution of herbicide-resistant weeds were other concerns.

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Weed Management Research and Extension Priorities

Herbicide-resistant weed management was identified by 48% of respondents as their top priority for research and extension. A variety of other topics, such as the development of new herbicide modes-of-action, integrated pest management, reducing off-target herbicide movement, cover crops, and farm safety were also listed as research and extension priorities.

Read More

The survey results were published recently in the Weed Technology journal. A copy is also available here.

Source URL: https://cropwatch.unl.edu/2018/nebraskas-top-weed-problems-and-most-common-herbicides