• By Tom Barber •
I have fielded several questions over the past week about dicamba regulations and what the rules “mean” and what can be sprayed etc. Most questions revolve around what is “legal to spray” after April 15 for pre-plant burndown, emerged corn, and Xtend soybean or cotton.
I will admit the way the rules are written it is confusing to know which products actually can be used for these different situations. The easiest way in my opinion to comply with the Arkansas State Plant Board regulations is to use Engenia, FeXapan or XtendiMax plus Vaporgrip for all of the above-mentioned applications because they are all labeled for these scenarios including applications in Xtend crops.
So for this scenario, from April 16 through May 25, only use the new dicamba formulations including Engenia, FeXapan, XtendiMax plus Vaporgrip Technology.
Tavium plus Vaporgrip Technology, a new premix of dicamba and S-metolachlor (Dual Magnum) from Syngenta, just received federal and state approvals last month. However it is only labeled for Xtend cotton and soybean crops, so this could be another option for those applications but not in corn.
After April 15
All the updated rules and regulations around dicamba applications can be found on the Arkansas State Plant Board website, here (https://www.agriculture.arkansas.gov/arkansas-dicamba-information-updates) and I would encourage anyone with questions about these rules to contact the Arkansas State Plant Board.
In addition, there is a frequently asked question publication that the plant board released and can be found at the following link, https://bit.ly/2XwF45Y .
Please read the updates and don’t take my word for it. Additionally, prior to spraying Engenia, FeXapan, Tavium or XtendiMax, be sure to read all the label language for the product you plan to spray. These can be found online fairly easily; Agrian (https://www.agrian.com/labelcenter/results.cfm) is just one of many product search websites that can be used.
What does this mean for Arkansas?
From April 16 through May 25, all dicamba applications must be made per Arkansas State Plant Board and Federal Label restrictions. For Arkansas that means that applicators must:
1. Maintain a one (1) mile buffer, in all directions, from University and USDA research stations, certified organic crops, and commercially grown specialty crops (defined as a minimum of 1,000 plants or the average annual crop sales for the previous three-years exceeding $25,000);
2. Applicators are prohibited from using tank mixes of products containing the active ingredient Glyphosate mixed with pesticides containing the active ingredient dicamba labeled for in crop use;
3. During application a ½ mile buffer zone in all directions from non dicamba-tolerant crops must be maintained.
If the ½ mile or 1 mile buffers do not apply based on the lack of sensitive crops surrounding the application, the Federal Label buffers still apply. Those include a 110 feet downwind buffer between the last treated row and the nearest downwind field edge as well as a 57-foot buffer in all directions from the field of application in counties designated with endangered species.
These counties in Arkansas include Clay, Craighead, Crittenden, Cross, Jackson, Poinsett, Prairie and Woodruff. Check this website for any updates: https://www.regulations.gov/document?D=EPA-HQ-OPP-2016-0187-0974.
Additional tankmixes that are allowed are listed on each individual product website, they include:
All applications should be made at a minimum of 15 GPA for best weed control.
In addition to the above-mentioned rules, check the previously mentioned product websites for correct application requirements which include but are not limited to: adequate record keeping, correct nozzles, application pressure, boom height, ground speed and wind speed restrictions.
According to the federal label, applications to Xtend soybean cannot be made more than 45 days after planting or beginning bloom, whichever occurs first. Applications to Xtendflex cotton cannot be made more than 60 days after planting or mid-bloom, whichever comes first.
This is pretty much a moot point for Arkansas, as our cutoff date for all dicamba applications without a permit is May 25.No applications of approved dicamba formulations can be made during periods where an inversion is present (usually during low wind), and during nighttime hours. Legal applications of these dicamba formulations can only be made 1 hour after sunrise with a cutoff of 2 hours prior to sunset to reduce applications during a potential inversion.
For Arkansas producers, all applications of any dicamba formulation are banned after May 25. Growers who farm inside the Mississippi river levee can apply for a permit through the Arkansas State Plant Board to make applications later than the May 25 cutoff.
I hope this clears some questions up and given the tight supply of quality planting seed for soybean this year, I imagine there will be all technologies planted in a given area just to have enough seed for planting.
I would like to encourage everyone if they haven’t already to sign up their fields in the FieldWatch program so your neighbors know what technology is planted next door. Below are the links to add a field. To check on fields near your spray area, you can view the Arkansas map containing all reported crops at: https://ar.driftwatch.org/map.
Dr. Tom Barber is a University of Arkansas Extension weed scientist. He may be reached at firstname.lastname@example.org