Farm Progress

This year, 2,365 farmers and other applicators who plan to apply dicamba on cotton and soybeans were trained in 31mandatory sessions across North Carolina.

John Hart, Associate Editor

March 29, 2018

6 Min Read
Don York, left, a Guilford County farmer, discusses dicambia stewardship following a training session at the Caswell County Civic Center in Yanceyville with Dr. Alan York, William Neals Reynolds distinguished professor emeritus of crop science at North Carolina State University. Don York and Alan York are not related.

From Jan. 31 at the Southern Farm Show in Raleigh to March 7 at the Southeastern North Carolina Ag Events Center in Lumberton, Dr. Alan York made the rounds all across North Carolina delivering mandatory training for anyone who had plans to apply dicamba on cotton and soybeans this year.

“That’s basically all I’ve been doing since January,” York told Southeast Farm Press after he completed that final training session.York is Williams Neals Reynolds distinguished professor emeritus of crop science at North Carolina State University.

This is York’s second year of conducting the mandatory dicamba training. This year, 2,365 farmers and other applicators were trained in 31 sessions across the state. In addition to York, Dr. David Jordan with N.C. State and county agents helped in the training. Last year, more than 2,900 attended the mandatory training sessions across North Carolina.

This year, unlike last year, any person who actually runs the sprayer must complete the training. Dicamba is a restricted-use pesticide with a two-year label that expires this year.

Make or break

York says the main take-home message from the sessions is “be real careful when applying dicamba to your cotton or soybeans; this is the make-or-break year for the technology.” If drift is an issue in 2018 like it was in 2017, EPA will very likely ban its use once the label expires this fall.

“This is really good technology that works. It equals or beats every other option we have available, particularly as we have run into PPO resistance. Whether or not we can keep this option depends on what we do this year,” York stressed.

“What we do in the Southeast may not matter much anyway. We need the whole country to do a better job than we did last year or we will lose dicamba. EPA doesn’t want to pull this technology away from us; they know we need it.  But we need to do better if we don’t want to lose it,” York said.

In a training session in Yanceyville, York noted that both glyphosate-resistant Palmer amaranth and PPO-resistant Palmer amaranth are picking up in North Carolina. Resistance will likely get worse before it gets better. “We have a finite amount of tools we can work with and because of resistance, we keep breaking our tools, and we’re not seeing them replaced,” he said.

That’s why it is so important that farmers across the country take every step to avoid drift damage to sensitive crops. York stressed that very small amounts of dicamba can cause physical symptoms to sensitive crops.

“Most of your broadleaf crops are way more sensitive to these auxin herbicides than they are to other things that you may be used to spraying,” York said in the Yanceyville training session.

Any crop, except turf grasses, corn, sorghum and small grains, is sensitive. Any broadleaf crops that don’t that are not resistance to dicamba or 2, 4-D are also sensitive. Tobacco and non-Xtend soybeans are particularly sensitive to dicamba, while cotton is highly sensitive to 2,4-D. Fruits, vegetables and ornamentals are also sensitive crops.

Damage to sensitive crops depends on the amount of drift that takes place and the growth stage of the crop. York notes that if dicamba hits sensitive soybeans when they are still in the vegetative stage, leaf coupling may occur, but yield loss is generally not an issue.

“On the other hand, if damage occurs later in the season, after the soybean plants start blooming, your odds of seeing a yield reduction go up,” York said.

The biggest issue, particularly for tobacco, is marketability. Tobacco contracts specify that there can be no residue of unregistered pesticides on the crop. Dicamba is an unregistered pesticide for tobacco. The same is true for vegetables. Vegetable crops with dicamba damage cannot  be marketed.

Vapor vs. Spray

In the training, York specified the difference between vapor drift and spray drift. Spray drift occurs while you are spraying and is primarily a function of droplet size.  Vapor drift occurs after you spray.

“I think spray drift is the one that’s going to get most people in trouble. A lot of things affect spray drift: nozzles, the pressure you’re running and how fast you are travelling across the field. Small droplets drift. Avoid small droplets.”

To prevent small droplets and to avoid driftable fines, all dicamba labels mandate certain nozzles and pressures that result in large droplets. In addition, York urges farmers to use a drift reduction agent in their tank mix when they apply dicamba.

The boom must be low enough so that dicamba is applied 24 inches or less above your target. And sprayer speed cannot exceed 15 miles per hour. Moreover, there are specific wind speeds. Dicamba can be applied only when wind speeds are three to 10 miles per hour.

The minimum wind speed is established to avoid the risks of thermal inversions. “Thermal inversions were suspected of contributing to off-target dicamba problems in the Mid-South in 2017,” York said.  Thermal inversions should not be an issue if winds are over 3 MPH.

In addition, federal dicamba labels were revised to specify application only from sunrise to sunset in 2018.The labels also say don’t spray if the wind is moving toward sensitive crops or sensitive areas.

Sensitive areas include residential areas, bodies of water, native vegetation and known habitats to threatened and endangered species, including woods, field borders and ditch banks. “Labels for all dicamba herbicides require an unsprayed downwind buffer for sensitive areas,” York said.

Weeks before damage shows

Vapor drift occurs when dicamba moves in a gaseous form after has been deposited on the intended target. York notes that vapor drift can occur hours or days after application. It primarily depends upon the herbicide used and how it is formulated. That is why only certain brands are registered for use on Xtend crops.

Temperature and humidity also impact vapor drift and high temperatures increase vapor drift potential. There are no temperature restrictions on labels for the new dicamba formulations. However, the XtendiMax label does call for extra precautions when temperatures are above 90 degrees Fahrenheit. York urges greater precautions on hot days.

“If it’s 2:00 or 3:00 in the afternoon and it’s so hot you can hardly stand to be outside and there is tobacco down the road, that might not be your day to spray,” York said.

There are no temperature restrictions in North Carolina, but York urges applicators to be careful when temperatures are above 85 degrees Fahrenheit.

It is also critical to check your liability insurance if you use dicamba. If drift does occur, York urges farmers to talk to their neighbor and try to work it out before filing an official complaint with the North Carolina Department of Agriculture.

“It takes two to three weeks before the damage shows. As soon as you see damage, the two parties need to get together and try to work it out. Come to some kind of agreement on how you’re going to handle damages if there are any damages,” York advised.

 “If you can’t come to an agreement, that’s when you call NCDA. If you’re going to call NCDA, don’t wait until after harvest when your crops are gone and then call. They need something to look at. I encourage you to work it out between yourselves,” York said.

Alan_York_Dicamba_Training_1.jpg

Alan York with North Carolina State University leading one of the mandatory dicamba training sessions in Yanceyville.

About the Author(s)

John Hart

Associate Editor, Southeast Farm Press

John Hart is associate editor of Southeast Farm Press, responsible for coverage in the Carolinas and Virginia. He is based in Raleigh, N.C.

Prior to joining Southeast Farm Press, John was director of news services for the American Farm Bureau Federation in Washington, D.C. He also has experience as an energy journalist. For nine years, John was the owner, editor and publisher of The Rice World, a monthly publication serving the U.S. rice industry.  John also worked in public relations for the USA Rice Council in Houston, Texas and the Cotton Board in Memphis, Tenn. He also has experience as a farm and general assignments reporter for the Monroe, La. News-Star.

John is a native of Lake Charles, La. and is a  graduate of the LSU School of Journalism in Baton Rouge.  At LSU, he served on the staff of The Daily Reveille.

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