Assessing the Impacts of PGR-Based Weed Management Systems to Plant and Insect Diversity in Agricultural Landscapes

EPA Grant Number: FP917131
Title: Assessing the Impacts of PGR-Based Weed Management Systems to Plant and Insect Diversity in Agricultural Landscapes
Investigators: Egan, John F
Institution: Pennsylvania State University
EPA Project Officer: Lee, Sonja
Project Period: August 23, 2010 through August 22, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Pesticides and Toxic Substances


The impending commercialization of cotton and soybean genetically modified for resistance to plant growth regulator herbicides (PGR) including dicamba and 2,4-D will allow these compounds to be used much more widely in the future. Because these herbicides are volatile and prone to drifting off of crop fields, there is the potential for non-target damage to susceptible crops and natural vegetation. Focusing on dicamba, my research objectives are to quantify dicamba vapor drift at field and landscape scales and to measure the effects of low doses of this herbicide on susceptible crops and natural plant and insect communities in agroecosystems.


To combat a crisis with glyphosate resistant weeds, the biotechnology industry is developing crops that can tolerate other herbicide ingredients, including the plant growth regulator herbicides (PGR) dicamba and 2,4-D. A potential problem is that PGR herbicides can be volatile and often move away from targeted fields as droplets and vapors. My research will quantify vapor drift of PGR herbicides and explore potential risks to farmers growing susceptible crops and to natural habitats.


Dicamba vapor drift will be empirically measured at field scales by applying the herbicide to test plots and measuring emitted vapor concentrations at increasing distances using potted soybeans as a bioassay system. These results will be translated to landscape scales using GIS simulations that combine this data with previously-used air dispersion models. A comprehensive literature based meta-analysis will assess the effects of drift-level doses of dicamba on soybean, cotton, and other important susceptible crops species. Effects on natural plant and associated insect communities will be assessed using experiments on field edge and hedge row habitats treated with low doses of dicamba.

Expected Results:

My research will provide data to ensure that PGR-resistant crops are commercialized with a robust understanding of any potential risks to environmental quality. Data on the dynamics of dicamba vapor drift will help develop strategies to minimize or avoid vapor drift while using this herbicide effectively. A comprehensive analysis of crop susceptibility will help farmers understand drift risks to neighboring fields and to gauge economic costs from herbicide drift incidences. Analysis of effects on natural vegetation will produce understanding of the sensitivity of these habitats to herbicide drift and the potential effects on associated ecosystem services including pollination.

Potential to Further Environmental/Human Health Protection:

PGR resistance biotechnology is being developed as a solution to a growing worldwide crisis with glyphosate resistant weed species. Complementing the transgenic technologies advanced by the biotechnology industries, farmers and researchers have for decades been developing sustainable, integrated weed management (IWM) approaches. While herbicides are an effective and important component of IWM systems, due to their unique volatility and toxicological properties, widespread use of PGR herbicides may pose unique risks to agroecosystems. At this critical juncture, my research will encourage a reinvestment in IWM science and provide data to ensure that PGR-resistant technologies are implemented within a robust understanding of any potential risks to environmental quality.

Supplemental Keywords:

herbicide resistance, glyphosate, dicamba, agroecosystem, pollination,

Progress and Final Reports:

  • 2011
  • 2012
  • Final