Published: November 15, 2017

For the second year, a major ag story has been the use of dicamba on soybeans that have been genetically engineered to tolerate it (Xtend trait). The manufacturers of these dicamba products (Monsanto and BASF) had taken steps and invested a lot of money to make these newly approved formulations less volatile (e.g. XtendiMax, Engenia, and FeXapan). Last year some growers tried using older formulations of dicamba and the off target movement was very bad. So for 2017, the new formulations were available and everyone was wondering if they would help dicamba stay put. Dicamba has been around for quite some time, but was rarely sprayed into the hot humid periods of the summer, when off target movement is of higher risk. The driving interest in mid-summer use of it is to combat waterhemp in soybeans, as waterhemp has become resistant to a number of herbicides, glyphosate most recognized (with Roundup Ready soybeans).

The 2017 results are deeply troubling. The Missouri Department of Agriculture is currently investigating over 280 dicamba-related injury cases (most are in the bootheel), and based on University of Missouri Extension field visits. Our weed scientist Kevin Bradley estimates 325,000 acres of soybean were injured by dicamba across 54 counties in Missouri (Figure 1). On a national scale, there are now more than 2,200 dicamba-related injury investigations being conducted by various state Departments of Agriculture, and more than 3.1 million acres of soybean estimated with dicamba injury. Weed scientists across the country have never seen anything like this before; this is not like the introduction of Roundup Ready or any other new trait or technology in our agricultural history.

Figure 1. Official dicamba-related injury investigations as reported by the Missouri Department of Agriculture (updated August 17, 2017).

How did commercial vegetable fields fare this year with unwanted herbicide contamination? There were a handful of fields affected in the bootheel by dicamba. There was a serious incident of drift to a vegetable field in Boone County, not related to dicamba, but from a typical pre-plant burndown in a nearby field. While the wind was light, the nozzles used created smaller droplet size, better suited for applying fungicides or insecticides, than herbicides (which should be larger, to reduce risk of spray drift). So overall, not too bad for vegetable growers nearby produce auctions.

It is unknown now what the various Departments of Ag across the country are going to do about use of dicamba on Xtend soybeans. Many came out mid-summer with additional restrictions and subsequent off target movement still occurred. MU's Kevin Bradley has recommended that Missouri go back to using dicamba at a timeframe and in a manner when it has been used "successfully" in the past. This would be during April and May, as with typical corn production. With the unknown about future dicamba use, can you do anything? Yes, consider registering your farm with DriftWatch. It will help companies that do spraying aware that you produce sensitive crops.

Are other Amish and Mennonite growers affiliated with produce auctions registered with DriftWatch? Yes! This program is active in Indiana and in the northern part there are several hundred Amish or Mennonite farms registered. There are also some growers nearby Rich Hill and the North Missouri Produce Auction who registered. They had their county extension center assist with the computer.

You might ask, since my neighboring row crop farmer knows what I grown, isn't that good enough? Well, this is a changing situation. With the increasing complexity (and liability) of applying these newer products (e.g. dicamba products), many growers are contracting this out to contractors and other certified applicators (e.g. MFA). These companies use DriftWatch to be aware…the message from a farmer, to the company clerk, to the person mixing and sending out the sprayers, to that spray operator may not get thru. However, once you are on the DriftWatch mapping system, they will or should be. Also, remember that many pasture and hay crop farms are smaller and will contract out their spring herbicide applications, which coincide with early plantings of many vegetables.

Is it free? Yes. Who pays for this program you might ask? Chemical companies and others in the business of making money applying products, because 'they want to know where you are so they don't accidentally harm you'. The only 'catch' is that you need to acknowledge that your farm location will be posted on a website used for DriftWatch, BeeWatch, or FieldWatch. For more information or to register, go to: http://www.fieldwatch.com/.