Weed science Society of America Logo


Dicamba Research Workshop – Final Report and Presentations

WSSA Research Workshop for Managing Dicamba Off-Target Movement

FINAL REPORT: available here. This report is a compilation of presentations and action items from the discussions held at the workshop.

PRESS RELEASE: available here.

Executive Summary:

The Weed Science Society of America (WSSA) sponsored a research workshop on off-target movement of dicamba on April 16 -17, 2018 in Arlington, VA. WSSA invited a broad group of subject experts including weed scientists, state and federal regulators, application technology specialists, and representatives of dicamba registrants to discuss technical issues related to the off-target movement of dicamba observed and reported in 2016 and 2017, and to identify potential research objectives. The research workshop agenda was divided into four topic areas: I) Non-target impacts; II) Volatility; III) Application; and IV) Formulation. Within each topic area, presentations were made to provide an overview and to identify information that was not known and data gaps to be addressed going forward. Following the presentations, discussion was facilitated among participants to identify areas of concern and research questions that were subsequently ranked in order of importance. Following this compilation, suggested action items within each topic area were identified and included the following:

 Compile a comprehensive account of areas planted in dicamba-resistant crop cultivars by county, and quantities of all formulations of dicamba sold at minimum by state.

 Relate reported damage complaints to terrain and weather conditions.

 Improve deficiencies with herbicide labels to address: 1) lack of uniformity in label organization; 2) difficulty in finding and interpreting use instructions; 3) names of dicamba sensitive crops, landscape and native plants, and trees; 4) “neighboring distance” for sensitive crops; 5) descriptions of conditions leading to atmospheric inversions to protect applicators and neighbors.

 Coordinate applicator training such that all trainers present the same detailed message.

 Perform research to better characterize the potential volatility of new herbicide formulations.

 Perform research to better determine: 1) dose vs. damage relationships for key crops; 2) how to protect growers, property owners, and the public from off-target movement; and 3) modes of dicamba movement that are not currently accounted for.

There was sentiment from the group that the widespread non-target movement of dicamba was egregious and resulted in damage to crops, private properties, and native vegetation. Although amelioration of this situation was partly outside of research, attribution of liability should be addressed by appropriate authorities, particularly for horticultural growers who are suffering heavy financial losses. More funding for public research is needed. Concern was expressed that USDA-ARS and USDA-NIFA were not funding the type of research needed to manage off-target pesticide movement.

RESEARCH WORKSHOP PRESENTATIONS: (Click the titles to download the PDF files)

  1. Dicamba Non-Target Impact: Agronomic Crops (Dr. Bryan Young, Purdue University)
  2. Research Workshop for Managing Dicamba Off-Target Movement Specialty Crop Focus (Dr. Steve Smith, Red Gold, Inc.)
  3. Thinking Through Non-Target Effects (Dr. Dave Mortensen, Penn State University)
  4. Dicamba: Where it Happened? How it Happened? Why it Happened? (Dr. Richard Zollinger, North Dakota State University)
  5. The Effect of Formulation on Dicamba Volatility as Measured by Low Tunnels (Dr. Dan Reynolds, Mississippi State University)
  6. Dicamba: What we Know & What we Do Not Know (Dr. Thomas Mueller, University of Tennessee)
  7. Using Pesticide Wisely (Dr. Daniel Culpepper, University of Georgia)
  8. Temperature Inversions and Dicamba: What We Know and What We Don’t (Dr. Richard Grant, Purdue University)
  9. Physics of Particle Drift (Dr. Andrew Hewitt, The University of Queensland)
  10. Assessment of Formulation Use (Dr. Kevin Bradley, University of Missouri)
  11. Perspectives of Illinois Fertilizer & Chemical Association (Jean Payne, Illinois Fertilizer and Chemical Association)