Herbicide Resistance

Palmer amaranth in corn
Figure 1. Glyphosate-resistant Palmer amaranth infesting corn field in south central Nebraska. (Photos by Amit Jhala)

Grower Q&A: Is this Herbicide-Resistant Palmer Amaranth? June 23, 2017

This week growers facing challenges with Palmer amaranth questioned whether it was due to the product, the environment and lack of rain, or a resistant weed. Several factors could be at play, notes a UNL weed scientist, who recommends starting with preemergence herbicides with residual activity to get the best control.

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Glyphosate-resistant marestail

Postemergence (Rescue) Herbicide Options for Control of Glyphosate-Resistant Marestail in Corn and Soybean May 24, 2017

Several factors have contributed to delayed applications and marestail escapes this spring. Includes recommendations for timely postemergence control in corn and soybean.

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Amit Jhala (left) and Debalin Sarangi
Amit Jhala (left) and Debalin Sarangi (right) along with other scientists detected pollen-mediated gene flow from glyphosate-resistant common waterhemp in Nebraska.

New Research Quantifies the Dispersal of Glyphosate Resistance Trait Through Pollen-Mediated Gene Flow May 18, 2017

The pollen-mediated gene flow was detected 38% to 54% at 0.1 meter distance and 5% to 9% at 50 meters, the highest distance tested in this study.

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marestail

Status of Herbicide-Resistant Weeds in Nebraska March 20, 2017

Nine weed species in Nebraska have now evolved resistance to at least one group of herbicides. Six weed species — common ragweed, common waterhemp, marestail, kochia, giant ragweed, and Palmer amaranth — have confirmed resistance to glyphosate. Rotate herbicide sites of action and weed control practice to avoid contributing to this trend.

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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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Marestail seedling and field infested with marestail
Figures 1 (inset). Marestail plant forming rosette in spring. Figure 2. Corn field infested with glyphosate-resistant marestail in eastern Nebraska. (All photos by Debalin Sarangi).

When is a Good Time to Scout and Control Glyphosate-Resistant Marestail? March 8, 2017

Marestail, also known as horseweed or Canada fleabane, is a winter or summer annual weed in Nebraska. Historically, marestail was found in waste area, field edges, along roadsides, and railway tracks; however, no-till crop production systems over the last 20 years favor marestail germination and establishment in agronomic crops in Nebraska.

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