Success StoryOff-Target Movement of Dicamba in Fulton County



Off-Target Movement of Dicamba in Fulton County

Author: Benjamin Rudy

Planning Unit: Fulton County CES

Major Program: Chemical Crop Management Tools

Plan of Work: Increasing Agricultural Stability through Cropping Systems, Marketing, and Pest Management

Outcome: Intermediate Outcome

As producers continue to manage Palmer Amaranth and Resistant Water Hemp, an ever-growing problem in Fulton County and other counties in Kentucky, many producers switched to the newly approve Dicamba technology.  This new technology allowed soybeans that were previously susceptible to dicamba herbicides to be resistant.  Along with these newly resistant soybeans, the three major chemical companies developed a newer, lower volatile dicamba herbicide.


During the 2017 growing season, producers in Fulton County began to grow the newly approved dicamba resistant soybeans in Kentucky counties as well as the rest of the U.S.The year prior, dicamba resistant soybeans were allowed to be grown in the U.S. but were not sprayed as the Environmental Protection Agency (E.P.A) had not approved the newest formulations of dicamba (Xtendimax, Engenia, & FeXapan) with federal labeling for soybean use.In 2016, other states saw issues in non-dicamba resistant soybeans that were near dicamba resistant cotton fields. During the winter months of 2016 and early 2017 numerous producer meetings were conducted on educating retailers and producers on application of the new formulations.  During the beginning of 2017, 56 Fulton County producers received Private Applicator Training, 154 producers from the Purchase area attended the Winter Ag Conference, and 180 producer received the Fulton County ANR Newsletter.  Guidelines and information on safe application of pesticides as well as dicamba updates and safe application were included at all of these meetings and in newsletters. As a result of talking with these producers after they were presented with the information, the majority stated they had adopted these technologies, and felt comfortable with the application of these new sprays.


As we moved into planting and early into the growing season, we were not seeing or hearing any issues in Fulton County.  Further South in Mississippi, Arkansas, and Tennessee they were beginning to have issues flare-up with numerous cases of dicamba injury on soybeans, trees, orchards, etc.  The first calls of suspected dicama injury were received around July 4th. After field observations, photos and samples were collected and sent to the Plant Diagnostic Lab.  It was confirmed these samples were positive for Group 4 Growth Regulator injury.Upon further investigation a large number of acreage in the Lower Bottom area of Fulton County was showing similar injury on non-dicamba resistant soybeans.  After other producer calls, the Weed Specialist from Princeton’s Research and Education Center was asked to come down and survey the area and talk with producers on July 11th.  During that meeting, producers in the fields surrounding some of the questioned fields were asked various questions on spray application, weather conditions, and chemical formulations, and we visited some of these fields to discuss wind directions and physical symptoms of the plants.  At that time, the producers asked what the effect on yield would be. The specialist explained there were no scientific research to determine the percent loss.  After the meeting the Fulton County Extension Agent, the Carlisle County Extension Agent, and Weed Specialist toured other areas of the county and determined that at that time 12 thousand acres were effected.  From this meeting forward, through most of the growing season, one to two days a week were spent looking at soybeans that were injured from a Group 4 herbicide.  As the season progressed in areas where plants received possibly one or two exposures to dicamba they appeared to grow out of the symptoms, but in areas that received multiple exposures (4+) the soybeans appeared to remain effected physically.  In these areas the leaves remained mouse eared, branches of the plant grew vertically and did not canopy correctly, and some producers noticed skips or blanks in seed pods.As the season ended, it was estimated that around 17 thousand acres were effect.  Producers began harvesting these beans and overall the producers did not notice a yield loss on whole field averages. In general, yields were at or above production averages.  As some of the producers began to look at yield maps, trends showed single digit percent losses compared to other areas of the field (proximity to fields sprayed with dicamba).

During the 2017 production year a number of land grant university weed specialist began additional research on dicamba in regard to the off target movement.  In many of the research projects, the volatility of these products was questioned and compared to older formulations of the product.Some of the questions about off-target movement were answered, but more questions also arose.  This only made discussion of dicamba use amongst producer and retailers heated and opinionated.


According to Kentucky Ag Statistics, Fulton County produces annually about 51,000 acres of soybean or 2.5 billion bushels of soybean.  In the 2012 U.S. Ag Census $17.8 million of soybeans were sold in Fulton County.These sales plus our other grain crops ranks Fulton County 16th in the state and 10th in the state for just soybean sales.  Fulton County also ranks in the top 5 counties in the state in number of acres of soybeans grown per square mile.  In using these statistics 33% of our soybean acreage was effected by dicamba injury. 


As we begin to look towards 2018, producers are indicating the possibility of switching more acreage to the dicamba resistant soybeans and others are holding steadfast to herbicide resistant soybeans.  This mixing of resistant traits, especially in our river bottom areas, have spurred the need for more educational opportunities for local producers to better help them understand the chemical technology they are using, along with needing additional educational requirements for purchasing and spraying as required by the E.P.A. relabeling the Xtendimax, FeXapan, and Engenia products to a Restricted-Use Product.  During the months of December, January and February, the Agriculture and Natural Resource Agents for Fulton, Hickman, and Carlisle counties scheduled producer meetings with University of Kentucky and University of Tennessee weed specialists along with hosting four new required Dicamba-Specific Certification classes, and numerous Private Applicator Trainings.  All of these meetings and trainings are geared for safer pesticide application, identifying target weeds, weather conditions, and record keeping.  All with the primary goal to reduce off target movement incidents and have correct and timely application of pesticides.






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