CAES Newswire

 College of Agricultural & Environmental Sciences UGA Cooperative Extension
Menu
Published on 11/14/18

U.S. EPA extends registration of weed killer dicamba

By Clint Thompson

Georgia farmers scored what many view as a significant victory when the U.S. Environmental Protection Agency extended the registration of the controversial weed killer dicamba for two years. The herbicide can be used for over-the-top weed control in cotton and soybean fields, according to Stanley Culpepper, University of Georgia Cooperative Extension weed specialist.

Cotton and soybean growers implement the dicamba system in hopes of controlling Palmer amaranth — the No. 1 weed pest farmers encounter every year.

“Even in 2017, our growers noted that dicamba was an extremely valuable tool in managing Palmer amaranth. Keep in mind, in our state, the most problematic weed pests — Palmer amaranth, Palmer amaranth, Palmer amaranth and then maybe a morning glory or spider wart. It’s really Palmer amaranth that continues to drive the agronomic landscape in regards to weed control,” Culpepper said.

Culpepper serves on the EPA’s Science Advisory Board and has helped coordinate UGA Extension educational trainings for farmers and applicators about the dangers of pesticide drift that began in 2015. UGA teamed with the Georgia Department of Agriculture to create a training titled “Using Pesticides Wisely.” In 2017, there were zero incidents of auxin off-target incidents in Georgia.

If not managed correctly, glyphosate-resistant Palmer amaranth, commonly called “pigweed,” can quickly overtake a field. With enormous growth potential, it can reach heights of 7 to 10 feet and adversely affect cotton equipment moving through a field. Palmer amaranth can also rob cotton plants from receiving much-needed resources like water and nutrients. As a result, cotton yields can be reduced.

“I think if you survey any of our growers, if you look at my surveys that I’ve implemented, the EPA’s decision was extremely important because dicamba was very valuable and very successful for weed management, especially in a challenging year like 2018,” Culpepper said. “These technologies allow us a little better opportunity to catch up with Palmer amaranth.”

UGA Extension is documenting the actual value of dicamba to Georgia growers but Culpepper says, “it will be quite large, without a doubt in cotton production for 2018.”

According to the EPA, dicamba is a herbicide that is used on agricultural crops, pastures and turfgrass. Before 2016, dicamba was mostly used in late winter or early spring for the removal of broadleaf weeds prior to farmers planting their crops.

In 2016, the EPA first registered dicamba chemistries for over-the-top application of dicamba-tolerant cotton and soybean plants during the 2017 growing season.

The EPA made the following additional guidelines to further minimize damage resulting from dicamba on nontarget crops:

  • Only certified applicators may apply dicamba over the top.
  • Over-the-top application of dicamba is prohibited 45 days after planting soybeans and 60 days after planting cotton.
  • The number of over-the-top applications for cotton is reduced from four to two. Soybeans remain at two over-the-top applications.
  • Dicamba may only be applied from one hour after sunrise to two hours before sunset.
  • In counties where endangered species may exist, the downwind buffer will remain at 110 feet and there will be a new 57-foot buffer around the other sides of the field. The 110-foot downwind buffer applies to all applications and is not limited to counties where endangered species may exist.
  • To ensure consistency across all three products, the training period is being clarified for 2019 and beyond.
  • Tank clean-out instructions are improved for the entire system.
  • The label is enhanced to improve applicator awareness on the impact of low pHs on the potential volatility of dicamba.
  • Compliance and enforceability are improved through label cleanup and consistency.

Culpepper emphasizes two points that growers need to be mindful of if they want to continue using dicamba when registration runs out in 2020.

In the area of stewardship, farmers need to make sure the technologies they are using are applied on target and remain on target, without drifting to crops they weren’t intended for. Producers also need to be wary about resistance management and avoid overusing dicamba.

“If we go out and spray too much dicamba, we will lose those technologies. Palmer amaranth is not a normal weed. It’s going to win if you don’t make every intelligent decision that you can make,” Culpepper said.

For more information, see gaweed.com.

Clint Thompson is an agriculture writer based in Tifton, Georgia.

Authors:
Clint Thompson
Experts/Sources:
Stanley Culpepper
Palmer amaranth can reach heights of up to 7-10 feet. UGA Extension weed specialist Eric Prostko encourages farmers to continue to control Palmer amaranth even after their corn is harvested.
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Download Image
HurricaneHeleneGreenhouseDamageCropped CAES News
UGA Extension supports resilience in Georgia farm communities after Hurricane Helene 12/19/24 Emily Cabrera
Hurricane Helene wrought sweeping devastation across Georgia’s agricultural sector in late September, leaving an indelible mark on both the land and the people who tend it, bringing focus to vulnerabilities in Georgia’s farming industry and the need for more robust safety nets. In addition to the physical destruction, the hurricane took an emotional toll on Georgia’s farmers. In response, UGA Extension has prioritized mental health support.
At the 2024 Georgia Life Sciences Summit held Oct. 21-22 in Atlanta, Professor Quingguo “Jack” Huang of the College of Agricultural & Environmental Sciences received the Golden Helix Innovation Award for his research in technologies to mitigate “forever chemicals” in water resources. (Photo by Andrew Davis Tucker) CAES News
Nothing lasts forever: CAES professor finds solutions to break down ‘forever chemicals’ 12/05/24 Carson McAfee
University of Georgia Professor Qingguo “Jack” Huang always wanted to do one thing: solve problems. Growing up in a small city in central China, Huang’s favorite subject in elementary school was math, granting him the opportunity to work on many problems. In high school, his passion transitioned to science, where he learned he could feed those same interests in a way that benefited others. He was finishing high school in the 1980s when Rachel Carson’s Silent Spring made its way to Chinese newspapers, capturing Huang’s attention.
Georgia Simmons at the office of U.S. Sen. Warnock CAES News
Georgia 4-H alum, CAES student spends semester serving at the nation's Capitol 12/03/24 Josie Smith, Cooper Hardy
Third-year University of Georgia student and Banks County 4-H alum Georgia Simmons has been in the center of the political action this fall with the Georgia 4-H Washington DC Intern Program. Simmons, an environmental resource science major in the College of Agricultural and Environmental Sciences, works in the office of U.S. Sen. Raphael Warnock. As an intern on his staff, she interacts directly with policy experts and lawmakers, participating in the legislative process while earning a semester of credit hours.
Longtime faculty member George Vellidis was named the first permanent director of the Institute for Integrative Precision Agriculture. IIPA was launched in 2022 and has grown to include more than 70 faculty members. (Photo by Paul Privette for UGA CAES) CAES News
Vellidis named director of Institute for Integrative Precision Agriculture 12/02/24 David Mitchell
University of Georgia College of Agricultural and Environmental Sciences Professor George Vellidis has been named director of the Institute for Integrative Precision Agriculture (IIPA). His term began on Nov. 1, and he will serve as the unit’s first permanent director. “Dr. Vellidis has been a vital member of our UGA faculty for years and played a key role in launching IIPA,” said Chris King, interim vice president for research. “Whether it’s his impact as a first-class researcher and educator or the work he does behind the scenes to elevate our reputation in the field abroad, his presence has made UGA a hub for precision agriculture research.”
Mergoum at Creature Comforts CAES News
That's the spirit! 11/18/24 Maria M. Lameiras, Claire S. Kinnard
Wheat breeders spend years meticulously crossing varieties to coax the best traits out of each species, carefully propagating plant varieties that are healthier, heartier and better suited for the environments where they are grown. Professional brewmasters are equally painstaking when choosing the components that will give their beers a specific flavor profile.
TiftonCampusSunset2 CAES News
CAES Transfer Pathways Program expands enrollment access for rural students 11/12/24 Emily Cabrera
The Transfer Pathways Program is opening new doors for rural students who dream of attending the University of Georgia College of Agricultural and Environmental Sciences (CAES). In partnership with Wiregrass Georgia Technical College and Southern Regional Technical College, students who complete required coursework at these institutions can transfer to CAES to complete bachelor’s degrees in one of three majors — agribusiness, agricultural education, and agriscience and environmental systems.