Resistance Management

glyphosate-resistant Palmer amaranth
Figure 1. A female glyphosate-resistant Palmer amaranth plant in a soybean field in south-central Nebraska. This plant has the capacity to produce up to half a million seeds. (All photos by Parminder Chahal)

Glyphosate-Resistant Palmer Amaranth Confirmed in South-Central Nebraska

March 15, 2017

Palmer amaranth (Amaranthus palmeri S. Wats.) is a C4 dioecious species (separate male and female plants) native to the southwestern United States.

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Handy Bt Trait Table Revised for 2017

January 19, 2017
The Handy Bt Trait Table for US corn production has been updated for 2017. It includes information on all registered Bt corn hybrids commercially available and summarizes which insects are controlled by which hybrids, which Bt and herbicide tolerance traits are expressed in different hybrids, and the Insect Resistance Management Refuge requirements associated with these hybrids.

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Photos of pigweed species
Figure 1. Common pigweed species found in the Nebraska Panhandle. Palmer amaranth and waterhemp are ALS-resistant. Images, from top to bottom in each column, are of seed, seedlings, and plants in the vegetative growth stage. (Source Nebraska Extension EC94-138)

Management of ALS-Resistant Palmer Amaranth and Waterhemp in the Panhandle

January 6, 2017
Palmer amaranth and waterhemp in the Panhandle are resistant to ALS-inhibiting herbicides. While control of these weeds in dry bean can be challenging, corn, irrigated small grains, and sugarbeet make good rotation options for control. A combined pre/post treatment strategy controls weeds in the early part of the season when crop yield is most impacted and weed species are most susceptible to control inputs.

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Horseweed plant stages
Figure 1. (Top left) Newly emerged horseweed seedlings in the cotyledon stage. (Bottom left) Seedling in the rosette stage with true leaves formed. (Right) Horseweed plants that are early in the bolting stage.

Nebraska Extension Pest of The Month: Horseweed

January 5, 2017

Horseweed (marestail, Conyza canadensis L.) is a unique weed species that can emerge in both fall and spring. In Nebraska, unlike the eastern Corn Belt, horseweed populations predominantly emerge in fall as a winter annual.

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UNL greenhouse trial of glyphosate resistance in kochia
kochia in the greenhouse

Managing Glyphosate- and ALS-Resistant Kochia in the Panhandle

December 15, 2016
The development and management of pesticide-resistant kochia in dryland and irrigated systems in the Panhandle including a table of herbicide options for Nebraska.

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Figure 1. Marestail seedling growing in a no-till field. Due to its small size in the fall, pay special attention during scouting, especially in no-till fields where residue can hide seedlings.during scouting.
Figure 1. Marestail seedling growing in a no-till field. Due to its small size in the fall, pay special attention during scouting, especially in no-till fields where residue can hide seedlings.

Fall is Optimal for Marestail Management

October 28, 2016
With corn and soybean harvest nearing completion in Nebraska this is a great time to begin scouting fields for winter annual weeds like marestail. Timing is critical to successful control of marestail, especially in no-till soybeans as many populations have evolved resistance to glyphosate and ALS-inhibiting herbicides.

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Antibiotic Resistance Found to Naturally Occur in Soils

September 22, 2016

Sandra Avant, USDA ARS

U.S. Department of Agriculture (USDA) scientists have found antibiotic-resistant bacteria in Nebraska prairie soils that had little or no exposure to human or animal activity.

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Palmer amaranth
Palmer amaranth

Your Help Needed to Identify Palmer Amaranth Distribution in Nebraska

September 2, 2016
Nebraska Extension is requesting help in identifying the distribution of Palmer amaranth in Nebraska by taking this short survey.

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