New Traits for Weed Management in Cotton

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.

Dicamba ≠ 2,4-D

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).

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

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

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.

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

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

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.”

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.

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)

dimethylamine (DMA) salt O 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.

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.

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

Nozzle manufacturers use this categorization in their catalogs.

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.

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 http://www.asabe.org/standards/images.aspx

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”

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

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

Excellent resource on cleaning sprayers and other equipment Published Aug, 2015 >50 pages Detailed pictures and instructions https://ag.purdue.edu/extension/ppp/Documents/PPP-108.pdf

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.

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

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

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.