1. Dicamba Update
2019

3. 2017 total off-target movement (drift) complaints… 287
2017 dicamba drift complaints… 132
2017 percentage dicamba of total drift… 46%
2018 total drift complaints… 289
2018 dicamba drift complaints… 146
2018 percentage dicamba of total drift… 51%

4. Year Total Drift Dicamba Percent 2013 108 3 3 % 2014 100 5 5% % % % % % %
*2018 data is only partial at this point

5. Herbicide Drift – 2018 Indiana issues Sharpen Glyphosate
Auxin herbicides
Early season cases were not different in 2018 than most other years. Sharpen, glyphosate (Roundup), auxin (2,4-D and dicamba used in burndown programs) were the common herbicides that were causing injury to lawn plants and trees.

6. Nursery Drift Cases
Randolph – Light saflufenacil injury. 2,4-D on tomatoes in hoop house.
Saflufenacil sprayed on windy day. Nearest 2,4-D 2,000 feet away
Spencer – Light to heavy 2,4-D damage on landscape plants and grapes
Of 2 application dates given, both windy
Jackson – Moderate to heavy 2,4-D injury on many vegetables
Application on May 8th, very low winds. No 2,4-D in tank-mix
May 7th and 9th very windy, 3 other fields around nursery
One notable difference this year is the fact that we had 7-8 nurseries turn in drift complaints. Normally we have about 1 nursery/year turn in a drift complaint. Here are the 1st three cases turned in this year. 2,4-D made it into a hoop house from 2000 feet away in Randolph county. Heavy winds on the 2nd and 3rd cases. Some questions about accuracy of spray dates and herbicides sprayed in the 3rd case.

7. 2018 Label Changes Included
RUP classification
Mandatory dicamba-specific training for all users
Mandatory detailed recordkeeping requirements, including weather
Prohibit application near downwind sensitive crops
Clarified mandatory buffer requirements
Reduced max. wind speed from 15 to 10 mph
Beefed up tank cleaning requirements

8. 2018 OISC Dicamba Investigations
Evidence of off-target movement…100%
No documented violation… 15%
Documented drift violation only… 0%
Documented drift management violation only… 71%
Documented drift violation + drift management violation… 14%

9. Comparison of Investigations
Applicator License
Commercial 23% 35%
Private 62% 63%
No license 15% 2%
Target Crop or Site
Soybeans 92% 82%
Corn 6% 17%
Other 2% 1%
Product Applied
Engenia 45% 56%
FeXapan 7% 5%
Xtendimax 40% 32%
Other dicamba 8% 6%

10. Comparison of Investigations
Route of Off-Target Exposure
Particle drift 23% 13%
Application during an inversion 0% 0%
Volatilization 0% 0%
Undeterminable 74% 87%
Likewise, most of our first season complaints to date involved exposure to non-DT beans. As part of the investigation process, OISC attempted, somewhat unsuccessfully, to determine with scientific or evidence-based certainty the cause of the off-target movement. That has been extremely challenging. Perhaps most notable and disturbing about these results to date is that in well over half of the off-target incidents, OISC has been unable to determine why dicamba exposure occurred. This seems to be in contrast to what some recent industry media interviews have suggested. Historically OISC has looked for things like herbicide residue or exposure symptomology drift gradients moving away from suspected sources. In 2017 we observed a drift gradient damage pattern only 17% of the time. More often we found many instances of uniform exposure across entire fields, with or without the failure to follow all label restrictions.

11. Xtend Soybean Not Xtend Soybean
Picture of a field with no buffer. Many fields did not have buffers…

12. Route of Off-Target Pesticide Movement
Drift = misuse, if it can be proved
Application during inversion = misuse, if it can be proved
Volatilization = not misuse, if it can be proved
Found from Investigations that off-target movement can also be combination. Symptoms of movement from Volatilization and an Inversion are similar.

13. 2017 & 2018 Dicamba Complaint Violations
Total violative cases 93% 65% (?)
Off-target movement from drift 23% 13%
Wind blowing toward adjacent sensitive crops 46% 59%
Wind (or gusts) greater than 10 mph 4% 5%
Wind less than 3 mph 8% 7%
All drift management ? 56%
Drift management violations ≠ cause of off-target movement
You can see that completely legal use of these products in 2017 & 18 has been challenging. 95% of the investigations involved at least one or more label violations. That doesn’t mean that the documented violation was the specific reason for off-target movement, but it may have contributed.
It should be noted that failure to visit a website does not by itself cause off-target movement, but it can result in lack of site awareness and the likelihood of a complaint being filed. If the only documented violation was failure to visit a web site, usually only a warning would be issued.
However …

14. 2019 Dicamba Label Changes Everyone handling dicamba MUST be certified
Can no longer operate under the supervision of a certified applicator
Annual dicamba training is required
Will NOT be provided by Purdue Extension or OISC
BASF, Bayer, and Corteva will provide trainings
Applications up to R1 (flowering) or 45 days after planting
Application hours from 1 hour after sunrise until 2 hours before sunset
There were a few subtle changes on the label for this year. The changes that were relatively easy to interpret and affect everyone are outlined here. Please remember you have to go to additional Dicamba training to be certified to handle dicamba in 2019.
Some label changes are still being interpreted by OISC

15. 2019 Dicamba Label Changes
Managed areas can be included in downwind buffers
Mowed roadsides, rights-of-way, managed pastures, etc…
Application records must be generated within 72 hours of application
Do not allow tank mix to exceed pH 5.0
Omni-directional 57’ buffers for endangered species protection
Posey & Harrison Counties only

17. 2019 OISC Compliance Strategy
Increase monitoring & investigation of incidents involving tomatoes, vegetables, grapes, melons, gardens, ornamentals, flowers, trees, & organic crops.
For complaints of exposure to soybeans, on-site confirmation of dicamba exposure symptomology, but no attempt to document cause.
For insistent soybean exposure complainants, request a significant amount of upfront information & detail before initiating an investigation.
Utilize certification suspension & revocation for egregious violators. *
Work with stakeholders to identify measurement(s) of success for safe & effective application in 2019 & beyond.
* Further explanation on next slide of certification revocation.

18. 2019 OISC Compliance Strategy
If investigation found that mandatory training not attended,
Enforcement action = Revocation of certification for 5 YEARS
Applicators must do basics.
For 5 years cannot apply any Restricted Use Pesticide (ex. atrazine, gramoxone)
Retest at end of 5 years
The federal label states that this mandatory training is to be attended every year, so last year doesn’t count for this year. In Indiana, the Office of Indiana State Chemist has indicated that farmers involved with a drift complaint will have their permit suspended for five years if they use these dicamba products and do not have the annual training. This means that that person would be unable to purchase restricted-use pesticides.

19. Changes in 2019 label are highlighted text
Changes in 2019 label are highlighted text. Lower left corner has issue date. Check PARP educator resource site to assure have latest version. ppp.purdue.edu/private-applicators/educator-resources/
Recommend giving PPP-119 and addressing the changes with the audience.

20. The record sheet, addresses the label requirements
The record sheet, addresses the label requirements. Lists the registrant websites to find Mandatory Dicamba Training. From the website, the record sheet is also a fill-able pdf.doc
NOTE: last line item says to attach a 24c SLN label along with product label. This changed after the record sheet went to print. There is no SLN label for 2019, if go to website, none is available.

21. Weed Science Research
Following are slides of Weed science research presented by Bill Johnson during the zoom conference. Your choice for presenting.

22. Glyphosate-Resistant Soybean Injury 14 DAT80 60 40 20
500
0.1 1 10 50
Auxin Rate (g ha-1)
100
Dicamba - V2
Dicamba - R1
2,4-D - V2
2,4-D - R1
Visual Injury (%)
0.01% of 1X dicamba
2.5% of 1X 2,4-D
On the next couple slides with the USB logo in the lower right-hand corner we’re going to share with you some current work that is being led by Purdue and conducted in six different states. This slide here shows you a dose response of the two auxin herbicides exposed to soybean at two grow stages, V2 and R1. What this graphic shows you is that soybeans are much more sensitive to dicamba than they are to 24D and we’ve arbitrarily drawn a line at 10% injury and this data shows that it takes a much lower exposure of die Cambor then 242 cause 10% injury.

23. Glyphosate-Resistant Soybean Yield
% of 1X dicamba
5% of 1X 2,4-D
4000
3000
2000
1000
500
0.1 1 10 50
Rate (g ha-1)
Dicamba - V2
Dicamba - R1
2,4-D - V2
2,4-D - R1
Yield (kg ha-1)
The slide shows you the soybean yield response of low rates of these two herbicides. We’ve arbitrarily drawn a line at 10% yield loss and once again you can see that soybeans are much more sensitive to dicamba then they are 2-4D.

24. Seed Beans - Accelerated Aging Germination (RR2Y)
For individuals concerned about germination of soybean grown for seed, here is an experiment that looked at the germination percentage of seed beans exposed to dicamba. It’s important to note that they use rate is 560 g per hectare under normal conditions. This graphic shows you that it takes one 10th of the normal use rate to cause a negative impact on seed germination. This amount of injury would be 30 to 40% plant height reduction and shows that low levels of exposure that don’t result in significant damage to soybean do not have an impact on seed germination.
P=0.05

25. Multiple Exposures to Dicamba
One of the things that are work and all of the previous research has been published has not done is look at multiple exposure of soybeans to this herbicide. We have initiated work now to look at the impact of multiple exposures on sleeping growth parameters. We hope to report on that next winter.

27. Non-linear regressions of seed yield loss (A), plant height loss (B), seeds m-2 loss (C), seed mass loss (D), pod m-2 loss (E), seed pod-1 loss (F), reproductive nodes m-2 loss (G), pod reproductive node-1 loss (H), nodes m-2 loss (I), and percent reproductive nodes loss (J) as affected by dicamba treatments applied to soybean at the V2, V5, or R2 growth stages. Studies were conducted at the Throckmorton Purdue Research Center (TPAC) near Lafayette, IN, in 2009 and 2010 and at the Midwest Research Center (MRC) near Fowler, IN, in 2009.
We have done extensive work to look at the affect of this herbicide on various plant parameters. In this set of data slides here you can see the impact of low rates of this herbicide and the impact it has on yield loss plant tight the amount of seed produced the number of pods produced and other things. Pay close attention to the middle part of each graphic where are the X axis has grams per hectare. That is where you start to see interesting things happening to various plant growth parameters. You can spend all kinds of time going through this data, but the real message is low rates of hormone type herbicides can give you some higher numbers of reproductive nodes, but usually fewer seeds per unit area.

28. This slide shows information pool over all the Application timings
This slide shows information pool over all the Application timings. What this shows you is as is with low exposure rate you can get more reproductive nodes. However if you look hard at the data on the previous slide what you’ll see is at these lower rates of exposure where there’s more reproductive nodes, you have fewer seeds at these reproductive notes.

29. Relationship of visual estimates of soybean injury (0 to 100%) at 14 and 28 days after treatment and seed yield loss (%) of soybean plants treated with dicamba rates (0 to 22.7 g ha-1) at the V2, V5, or R2 soybean growth stages. Visual estimates of injury were taken at 14 and 28 days after treatment. Studies were conducted near Lafayette, IN, in 2009 and 2010 and near Fowler, IN, in Both regressions were significant (P <0.0001).
This slide shows soybean meal loss as a function of gioia estimates of injury taken 14 and 28 days after exposure. The key message here is that someone who is trained to do these types of visual assessments can do a pretty good job of entering a number into this model in predicting yield loss. However it takes someone who is pretty focused on learning how to do this and also knowing exactly when the soybeans were exposed to dicamba. The other take away from this data is that it requires pretty significant injury, 20% or more which usually also mean some kind of a height reduction before we start to observe yield loss at the end of the year.

30. Conclusions
Slight increases in number of reproductive nodes were noted at low exposure rates.
No yield increase was observed at any rate of exposure.
Measurable yield losses (usually 10% or more) were observed when 20% or more injury was observed at 14 to 21 days after exposure.
Symptoms observed by a trained eye at g/ha. Easily identified at g/ha.
The rate required to cause 20% injury varied from 1/1563 to 1/410 of the labeled field application rate for Xtend soybeans. This equates to less than 1 g/ha.
The rate required to cause a 10% yield reduction varied from 1/1064 to 1/510 of the labeled field application rate for Xtend soybeans. This equates to less than 1 g/ha.
Later exposure (V5, R2) causes greater yield loss than earlier exposure (V2)

31. Conclusions
Path analysis indicated that dicamba reduced seeds/m2, pods/m2, and reproductive nodes/m2 which were the main causes of seed yield loss from dicamba exposure.
Robinson, A., Simpson, D., & Johnson, W. (2013). Response of Glyphosate-Tolerant Soybean Yield Components to Dicamba Exposure. Weed Science, 61(4), doi: /WS-D