What do farmers’ weed control decisions imply about glyphosate resistance? Evidence from surveys of US corn fields

Authors

Seth J. Wechsler, USDA - Economic Research ServiceFollow
Jonathan R. McFadden, USDA - Economic Research ServiceFollow
David J. Smith, USDA - Economic Research Service

Date of this Version

2017

Citation

Pest Manag Sci (2017), DOI 10.1002/ps.4598.

Comments

U.S. government work.

Abstract

BACKGROUND: The first case of glyphosate-resistant weeds in the United States was documented in 1998, 2 years after the commercialization of genetically engineered herbicide-resistant (HR) corn and soybeans. Currently, over 15 glyphosate-resistant weed species affect US crop production areas. These weeds have the potential to reduce yields, increase costs, and lower farm profitability. The objective of our study is to develop a behavioral model of farmers’ weed management decisions and use it to analyze weed resistance to glyphosate in US corn farms.

RESULTS: On average, we find that weed control increased US corn yields by 3700 kg ha⁻¹ (worth approximately $US 255 ha⁻¹) in 2005 and 3500 kg ha⁻¹ (worth approximately $US 575 ha⁻¹) in 2010. If glyphosate resistant weeds were absent, glyphosate killed approximately 99% of weeds, on average, when applied at the label rate in HR production systems. Average control was dramatically lower in states where glyphosate resistance was widespread.

CONCLUSION: We find that glyphosate resistance had a significant impact on weed control costs and corn yields of US farmers in 2005 and 2010.