scholarly journals Genetically Engineered Herbicide-Resistant Crops and Herbicide-Resistant Weed Evolution in the United States

Weed Science ◽  
2017 ◽  
Vol 66 (2) ◽  
pp. 260-273 ◽  
Author(s):  
Andrew R. Kniss
Keyword(s):  
United States ◽  
The United States ◽  
Genetically Engineered ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Resistant Varieties ◽  
Weed Evolution ◽  
Sites Of Action ◽  
Herbicide Use ◽  
The Impact

Genetically engineered (GE) herbicide-resistant crops have been widely adopted by farmers in the United States and other countries around the world, and these crops have caused significant changes in herbicide use patterns. GE crops have been blamed for increased problems with herbicide-resistant weeds (colloquially called by the misnomer “superweeds”); however, there has been no rigorous analysis of herbicide use or herbicide-resistant weed evolution to quantify the impact of GE crops on herbicide resistance. Here, I analyze data from the International Survey of Herbicide Resistant Weeds and the USDA and demonstrate that adoption of GE corn varieties did not reduce herbicide diversity, and therefore likely did not increase selection pressure for herbicide-resistant weeds in that crop. Adoption of GE herbicide-resistant varieties substantially reduced herbicide diversity in cotton and soybean. Increased glyphosate use in cotton and soybean largely displaced herbicides that are more likely to select for herbicide-resistant weeds, which at least partially mitigated the impact of reduced herbicide diversity. The overall rate of newly confirmed herbicide-resistant weed species to all herbicide sites of action (SOAs) has slowed in the United States since 2005. Although the number of glyphosate-resistant weeds has increased since 1998, the evolution of new glyphosate-resistant weed species as a function of area sprayed has remained relatively low compared with several other commonly used herbicide SOAs.

Herbicide-Resistant Weeds in the United States and Their Impact on Extension

2009 ◽  
Vol 23 (4) ◽  
pp. 599-603 ◽  
Author(s):  
Barbara A. Scott ◽  
Mark J. Vangessel ◽  
Susan White-Hansen
Keyword(s):  
United States ◽  
Crop Production ◽  
The United States ◽  
Extension Education ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Herbicide Resistant ◽  
Agronomic Crops ◽  
Survey Results ◽  
The Impact

Herbicide-resistant weeds have impacted crop production throughout the United States, but the effect they have on extension programming has not been evaluated. In June 2007, 38 extension weed specialists throughout the United States, responded to a survey on herbicide-resistant (HR) weeds and the impact they are having on extension education programming. Survey results revealed that HR weeds have had a significant impact on extension programming particularly for agronomic crops. In the last 10 yr, agronomic weed specialists' extension programming was almost twice as likely to be impacted by the presence of HR weeds as compared to horticultural programming. In the next 5 yr, agronomic extension programming is twice as likely to be altered. Of 37 weed species reported, seven genera or species of weeds represented 80% of the major HR biotypes reported. These include Amaranthus species, horseweed, Setaria species, common lambsquarters, kochia, giant ragweed, and Lolium species. Five weed species (common ragweed, common lambsquarters, horseweed, kochia, and three foxtail species) exhibited weed by mode of action (MOA) interactions when evaluated as major or minor problems. Herbicide resistance problem severity differed for weed species, herbicide MOA, and crops. The results of this survey of university extension personnel confirm that HR weeds have impacted extension programming and will continue to impact programming in the future.

scholarly journals Relative toxicity of herbicide use in the United States 1990 to 2015

2016 ◽  
Author(s):  
Andrew R Kniss
Keyword(s):  
United States ◽  
Acute Toxicity ◽  
Chronic Toxicity ◽  
The United States ◽  
Genetically Engineered ◽  
Relative Toxicity ◽  
Herbicide Resistant ◽  
Widespread Adoption ◽  
Herbicide Use ◽  
Modern Farming

Herbicide use is among the most criticized aspects of modern farming operations, especially in response to widespread adoption of genetically-engineered (GE) herbicide-resistant crops. Many previous analyses of herbicide use have relied on flawed metrics in an attempt to evaluate trends in herbicide intensity and toxicity. Here, it is shown that herbicide use intensity has increased over the last 25 years in corn, cotton, rice, and wheat. Although GE glyphosate-resistant crops have been previously blamed for increasing herbicide use, herbicide use increased more rapidly in the non-GE crops rice and wheat. Even as herbicide use has increased, the chronic toxicity hazard associated with herbicide use decreased in 3 out of 6 crops, while acute toxicity hazard decreased in 5 out of 6 crops. In GE glyphosate-resistant crops, glyphosate accounted for 26% of corn, 43% of soybean, and 45% of cotton herbicide applications. However, due to it’s relatively low chronic toxicity, glyphosate contributed only 0.1%, 0.3%, and 3.5% of the chronic toxicity hazard in these same crops, respectively.

scholarly journals Relative toxicity of herbicide use in the United States 1990 to 2015

2016 ◽  
Author(s):  
Andrew R Kniss
Keyword(s):  
United States ◽  
Acute Toxicity ◽  
Chronic Toxicity ◽  
The United States ◽  
Genetically Engineered ◽  
Relative Toxicity ◽  
Herbicide Resistant ◽  
Widespread Adoption ◽  
Herbicide Use ◽  
Modern Farming

Herbicide use is among the most criticized aspects of modern farming operations, especially in response to widespread adoption of genetically-engineered (GE) herbicide-resistant crops. Many previous analyses of herbicide use have relied on flawed metrics in an attempt to evaluate trends in herbicide intensity and toxicity. Here, it is shown that herbicide use intensity has increased over the last 25 years in corn, cotton, rice, and wheat. Although GE glyphosate-resistant crops have been previously blamed for increasing herbicide use, herbicide use increased more rapidly in the non-GE crops rice and wheat. Even as herbicide use has increased, the chronic toxicity hazard associated with herbicide use decreased in 3 out of 6 crops, while acute toxicity hazard decreased in 5 out of 6 crops. In GE glyphosate-resistant crops, glyphosate accounted for 26% of corn, 43% of soybean, and 45% of cotton herbicide applications. However, due to it’s relatively low chronic toxicity, glyphosate contributed only 0.1%, 0.3%, and 3.5% of the chronic toxicity hazard in these same crops, respectively.

scholarly journals Herbicide-resistant weeds in turfgrass: current status and emerging threats

2020 ◽  
Vol 34 (3) ◽  
pp. 424-430
Author(s):  
James T. Brosnan ◽  
Matthew T. Elmore ◽  
Muthukumar V. Bagavathiannan
Keyword(s):  
United States ◽  
Herbicide Resistance ◽  
Production Systems ◽  
The United States ◽  
Target Site ◽  
Current Status ◽  
Weed Species ◽  
Management Tools ◽  
Herbicide Resistant ◽  
Target Site Resistance

AbstractHerbicide-resistant weeds pose a severe threat to sustainable vegetation management in various production systems worldwide. The majority of the herbicide resistance cases reported thus far originate from agronomic production systems where herbicide use is intensive, especially in industrialized countries. Another notable sector with heavy reliance on herbicides for weed control is managed turfgrass systems, particularly golf courses and athletic fields. Intensive use of herbicides, coupled with a lack of tillage and other mechanical tools that are options in agronomic systems, increases the risk of herbicide-resistant weeds evolving in managed turfgrass systems. Among the notable weed species at high risk for evolving resistance under managed turf systems in the United States are annual bluegrass, goosegrass, and crabgrasses. The evolution and spread of multiple herbicide resistance, an emerging threat facing the turfgrass industry, should be addressed with the use of diversified management tools. Target-site resistance has been reported commonly as a mechanism of resistance for many herbicide groups, though non–target site resistance is an emerging concern. Despite the anecdotal evidence of the mounting weed resistance issues in managed turf systems, the lack of systematic and periodic surveys at regional and national scales means that confirmed reports are very limited and sparse. Furthermore, currently available information is widely scattered in the literature. This review provides a concise summary of the current status of herbicide-resistant weeds in managed turfgrass systems in the United States and highlights key emerging threats.

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