Dow, Monsanto Respond to Herbicide Drift Damage
Midwest Wine Press has written and reprinted a number of herbicide drift damage stories. Herbicides that travel from corn and soybean fields into vineyards are a significant problem for Midwestern grape growers. In addition to reporting from the perspective of grape growers, we also wanted to present the views of herbicide producers. As described later in this article, the two big Midwestern based agri-chemical companies are taking steps to reduce drift damage with new herbicide formulations that are now under government review. (Bayer did not respond to a written interview request.)
Before delving into the specifics of how Dow AgroSciences and Monsanto are addressing herbicide damage to fruit growers, a brief review of glyphosate resistance in weeds is helpful. Both Dow and Monsanto began ramping up research into new herbicides when herbicide resistance problems surfaced around 2008 in Southern U.S. cotton fields. Monsanto research has focused mainly on dicamba and Dow has been working primarily with 2,4-D.
An explanation of herbicide chemistry is beyond the scope of this article, but 2,4-D was discovered in the 40’s and dicamba was developed in 1967. Both dicamba and 2,4-d are more toxic to grapes than glyphosate, according to a source at a leading Midwestern agricultural school. Glyphosate resistance has steadily spread north during the past five years. Dow reports that a 2012 national survey of farmers found that 44% of respondents reported some glyphosate resistant weeds in their fields.
Given the enormous implications of herbicide weed resistance, developing alternatives has become a major priority for manufacturers and a headache for government regulators. Last month, Midwest Wine Press reported that there are at least 15 new GMO herbicide resistant crops awaiting USDA approval. Most of these proposed herbicide resistant crops are intended to be used with a combination of chemicals instead of just glyphosate.
See related story: New Herbicide Resistant Crops Being Considered by USDA
During May, the USDA said it will extend the review period of new herbicide resistant crops developed by Dow and Monsanto. Reuters recently reported that approval will not occur before 2015, partially because of concerns expressed by fruit and vegetable growers.
Both Dow and Monsanto are now taking a two-pronged approach to addressing the drift concerns of “specialty” crop growers. Both companies said their proposed herbicides are chemically different than older versions of 2,4-D and dicamba.
In addition, both Dow and Monsanto have launched extensive education programs to teach farmers and other stakeholders about the proper use of herbicides. Herbicides can travel from their intended targets in two ways.
Most often, herbicide particles are carried by the wind as they leave the boom of the sprayer. This is called physical drift. More insidiously, herbicides can also turn into vapors and move long distances in a process called volatility.
According to Damon Palmer, U.S. Commercial Leader at Dow AgroSciences in Indianapolis, volatility was reduced 96% in the new Dow Duo Enlist herbicide, the herbicide component of the Enlist Weed Control System. Enlist Duo is a combination of 2,4-D, choline and glyphosate and is currently seeking EPA approval. St. Louis based Monsanto also reports reduced volatility in their Roundup Ready Xtend Crop System.
While volatility problems have largely been solved in the laboratory, physical drift is more difficult to address. Unfortunately, when herbicides do go off target, the cause is usually physical drift caused by the wind, according to John Combest, Media Communications Manager at Monsanto Company in St. Louis.
Combating Physical Drift
A recent report from the Weed Science Society of America showed that driftable spray droplets can be reduced from 30 percent down to two percent by simply upgrading the nozzle in current spray setups.
To incentivize row crop farmers to buy new larger droplet spray nozzles, Dow is developing a program to provide dealer discounts for new nozzles, according to Palmer.
Regardless of the type of sprayer used, larger, heavier herbicide droplets are not as susceptible to wind-borne travel as smaller, lighter droplets. Both Dow and Monsanto said that proposed herbicides have been engineered to produce larger droplets which are less likely to travel long distances in the air. Both companies stressed that the chemical compositions of the new versions of dicamba and 2,4-D are different that older versions, although neither company will divulge exactly what these differences are. According to Dow, the Enlist Duo herbicide includes 2,4-D choline, a new form of 2,4-D that is different from the amine and ester forms currently on the market. Dow calls its new 2,4-D choline combined with a proprietary manufacturing process Colex-D Technology.
Colex-D Technology minimizes the potential for drift by 45 percent and an additional 45 percent when applied with a low-drift nozzle, according to Dow. Monsanto is clear that it does not want farmers using older, more volatile versions of dicamba. “We have been communicating that we will not authorize the use of higher volatility herbicide products containing the active ingredients, in final form, dimethylamine salt (DMA) of dicamba and/or dicamba acid in the Roundup Ready Xtend Crop System,” Combest said. “Any use of old Monsanto herbicides is an ‘off label’ use and we don’t condone it.”
While Combest’s statements stop short of saying application of old versions of dicamba are illegal, the instructions on a herbicide label carry the weight of Federal law.
Both Dow and Monsanto have undertaken extensive farmer education programs with the goal of teaching applicators about minimizing drift. Monsanto currently has 20 “Learning Experience Centers” across the country, 13 of which are in the Midwest. The purpose of the Learning Centers is to work with dealers, farmers and academics to promote the proper use of herbicides and other agri-chemicals.
“Often when farmers hear the words ‘2,4-D’ and ‘dicamba’ they think of weed burn downs using older, generic versions of the products,” Combest said. “The Extend Crop System will allow applicators to spray dicamba and glyphosate over herbicide tolerant crops, which is totally different than the previous use of these products.”
Dow’s herbicide education program is called “Enlist 360 field training.” There are currently four Enlist 360 Technology Centers in the Midwest; Indianapolis, Lamberton, Minnesota, Ankeny, Iowa and Kansas City. At field training, growers, seed dealers, and retailers can take part in interactive, hands on training. Palmer said over 5,000 people attended Enlist 360 training this summer.
Enlist training includes demonstrations of different sprayer set ups so farmers can learn first hand how herbicide drift can be reduced. Demonstrations show the difference between using the new Enlist Duo herbicide with a low-drift nozzle compared to a tank mix of traditional forms of 2,4-D and glyphosate. Other aspects of the Dow and Monsanto training include proper boom height, maintaining buffer areas and the use of anemometers to confirm wind speeds are under 10 miles per hour.
“The delays in regulatory approval give us more time to do more education on the proper use of new herbicides,” Combest said. “Next year, Monsanto will set up additional sites to educate farmers about safe and effective herbicide use. The most important thing is education and training and that’s where we’re putting our main efforts.”
(Publisher’s note: During 2012, combined revenues for Dow AgroSciences and Monsanto were just under $20 billion. It seems reasonable for the companies to provide wind speed measuring equipment to smaller farmers who may be required by law to document wind speed and direction when applying herbicides.)
For more information on 2,4-d and dicamba herbicides, see this report from Purdue University: 2,4-d and Dicamba Tolerant Crops- Some Facts to Consider