Agronomy and Horticulture Department


Date of this Version

Spring 3-19-2012


Crespo, R.J. 2012. Understanding the biology, inheritance and mechanism of resistance of 2,4-D resistant waterhemp (Amaranthus tuberculatus) - Research Proposal. University of Nebraska-Lincoln. Lincoln, NE, US.


This publication contains the Research Proposal presented to the faculty of the Department of Agronomy and Horticulture of the University of Nebraska-Lincoln in the 2011-2012 academic year. The proposal presented here was developed as part of the Graduate Research Assistantship held by Mr. Crespo under the supervision of Dr. Greg Kruger (University of Nebraska-Lincoln) and Dr. Roch Gaussoin (University of Nebraska-Lincoln). I acknowledge the contributions of Dr. Mark Bernards (Western Illinois University), Dr. Pat Tranel (University of Illinois) and Dr. Stephen Baezinger (University of Nebraska-Lincoln). E-mail:


Waterhemp is a very well adapted summer annual weed to the U.S. Corn Belt region. Auxinic herbicides such as 2,4-D constitute effective and widely used herbicides to control waterhemp and other broadleaf species in cereal crops and turf grasses. Recently, Bernards et al. (2012) have reported a Nebraska waterhemp biotype has evolved resistant to 2,4-D. This finding represents the sixth mode-of action herbicide group to which waterhemp has evolved resistance to. Several attributes may have contributed to make waterhemp a very successful weed and prone to evolve to herbicide resistant: a high genetic variability, aggressive growth habits and high fecundity. The hypothetical scenario of a waterhemp population resistant to several herbicide mode of action constitutes a challenge on weed management, since a traditional herbicide use program could result in unmanageable situation. Several studies that have contributed to the basic understanding for auxinic herbicide resistance are presented. The proposed objectives of this study are: 1) to evaluate the response of the 2,4-D resistant waterhemp population to several other herbicides mode of action,, 2) to assess the type of inheritance pattern of 2,4-D resistance in waterhemp, and 3) to determine if the mechanism of 2,4D resistance in waterhemp is due to differential absorption, translocation, or metabolism of 2,4-D.