1. New Traits
for Weed Management
in Cotton

2. Enlist Cotton 2,4-D, glyphosate, glufosinate Soybean
New Traits
Corn
Enlist Cotton 2,4-D, glyphosate, glufosinate
Soybean
Xtend Cotton dicamba, glyphosate, glufosinate
Soybean dicamba, glyphosate
York has continued to focus much of his attention on the new technologies -- Enlist and Xtend. There appears to be much interest in these technologies, primarily to help us with resistant weeds.

3. Dicamba ≠ 2,4-D

4. Where are we with Enlist and Xtend traits?
Regulatory status
Trait
Crop
Traits Deregulated
Herbicide Registration
Enlist
Corn
September 2014
October 2014*
Soybean
Cotton
July 2015
Awaiting EPA
Xtend
January 2015
* Enlist Duo; registered in 15 states (NC not included).

5. XtendFlex Cotton in 2016: Seed are available
Not sure when there will be a label for dicamba-containing herbicide
It is ILLEGAL to apply any dicamba product not specifically labeled for use on XtendFlex cotton

6. Cotton Tolerance with New Traits; It’s Good
But, you may see minor injury;
the injury appears to be cosmetic

7. Weed control with the new traits
Alan York, NCSU
We anticipate a lot of interest, and a lot of use, of these new technologies because they can help us manage some problem weeds, such as glyphosate-reistant Palmer amaranth.

8. How do we manage off-target deposition in auxin-tolerant crops?

9. Impacts of Off-target Deposition
Reduced yield
Rate of exposure
Growth stage at exposure
Growing conditions at and after exposure

10. Impacts of Off-target Deposition
Reduced yield
Marketability of tobacco, fruits and vegetables
Has a tolerance been established?
What is residue level vs the established tolerance?
Injury may occur with non-detectable residue levels
Regardless of residue level, will buyer accept crop?
“If we see injury, we don’t want it.”

11. Sources of Off-Target Deposition
Vapor drift
Spray drift
Sprayer contamination
Off-target deposition can occur because of vapor drift, spray drift, or sprayer contamination.

12. How to avoid dicamba vapor drift?
Use only specified formulations; new formulations have very low volatility
XtendFlex: Roundup Xtend (glyphosate + dicamba DGA salt)
Xtendimax (dicamba DGA salt)
Engenia (dicamba BAPMA salt)

13. dimethylamine (DMA) saltO
C – OH Cl
O - CH3
C – O-
CH2 - CH2 - O - CH2 - CH2 – OH
+NH3
CH3
+NH2
CH3 - CH2 - CH2 - NH2
+NH
dicamba acid
dimethylamine (DMA) salt
diglycolamine (DGA) salt
BAPMA salt
Similar to what I showed for 2,4-D, dicamba is also an acid. Notice the red portion of the molecule. On top right, we have the dimethylamine salt of dicamba. That is Banvel and several generics, and that is the one with the reputation of vapor drift. In the center, we have the diglycolamine, trade name Clarity. And on bottom right, we have the BAPMA salt from BASF. Note the salt is a heavy molecule, and that along with some other chemical properties, make it the least volatile of the group.

14. Current Dicamba Formulations and Volatility**
Diglycolamine salt
Dimethylamine salt
Low volatility
High volatility
Brand
Manufacturer
Clarity
BASF
Banvel
Arysta
Clash
Nufarm
Diablo
(Nufarm)
Detonate
Tenkoz
Dicamba DMA
(Albaugh)
Dicamba HD
Albaugh
Rifle
Loveland
DiFlexx
Bayer
Sterling Blue
Winfield
Strut
** None of these products will likely ever be labeled for XtendFlex cotton.

15. How to avoid dicamba spray drift?
Use only nozzles and pressures that produce ultra coarse (UC) or extremely coarse (XC) droplets; basically AI or TTI nozzles

16. Nozzle manufacturers use this categorization in their catalogs.

17. Nozzles and Droplet Sizes
Dv0.1: 10% of spray volume in droplets less than this number
Droplet-Size
Spectrum
Dv0.5: 50% of spray volume in droplets less than this number, 50% of volume in droplets larger
What is particularly important is this lower end of the droplet sizes, call the Dv0.1. That means that 10% of the spray volume is made up of droplets smaller than that number. Data on Dv0.1 for specific nozzles is hard to come by; manufacturers typically do not present that data.

18. Nozzles and Droplet Sizes
Droplets < 105 μm are “driftable fines”
Prefer Dv0.1 at least 200 μm
This shows droplet diameter for the various droplet size categories. In the middle, we have the VMD, upon which the classification is based. Note that the Ultra coarse and Extremely Coarse categories have VMD’s of 500 or greater. But, note the Dv0.1. We prefer the Dv0.1 to be at least 200 microns. Droplets less than 200 microns are very subject to drift. Note that only the categories of Ultra Coarse and Extremely Coarse have Dv0.1’s greater than 200 microns.
Dv0.1
Dv0.5

19. How to avoid dicamba spray drift?
Use only nozzles and pressures that produce UC or XC droplets; basically AI or TTI nozzles
Boom height 20 to 24 inches
Photo courtesy of Stanley Culpepper
22”
38”
58”

20. How to avoid dicamba spray drift?
Use only nozzles and pressures that produce UC or XC droplets; basically AI or TTI nozzles
Boom height 20 to 24 inches
Wind 3 to 10 MPH; remember wind speed and direction changes during the day
Minimum 10 GPA spray volume
Max sprayer speed of 15 MPH
No AMS; greatly increases volatility
Do NOT spray if sensitive crop is downwind; if you can’t afford to buy the downwind crop, then don’t spray

21. Roundup Ready® Xtend Crop System AFTER SPRAYING
Triple-Rinse Clean-Out is Required
Properly and thoroughly clean spray equipment
Use triple-rinse method to thoroughly clean entire sprayer system
Triple-rinse is the most effective practice to reduce off-target movement from spray contamination of any herbicide
Sprayer parts can trap herbicide, and additives and surfactants can cling
Slide provided by Monsanto

22. Excellent resource on cleaning sprayers and other equipment
Published Aug, 2015
>50 pages
Detailed pictures and instructions

23. Most applicators are now using sprayers that are pretty sophisticated
Most applicators are now using sprayers that are pretty sophisticated. This publication addresses that, with all the nooks and crannies in a sprayer that you may think of but can retain residues. It also addresses other equipment such as the nurse tanks. It is an excellent information source, and highly recommended.

24. XtendFlex Cotton in 2016: Seed are available
Not sure when there will be a label
It is ILLEGAL to apply dicamba until a label is granted

25. Are More Problems Likely? YES
Illegal use of herbicides
More injury to nearby crops due to volatility
Accidental applications to crops that do not have the Enlist or Xtend herbicide-resistant trait

26. Possible Solutions Approve Section 18s ASAP
In the future, approve new herbicides so they are available at the time new crops with herbicide- resistant traits are being sold commercially.