**1/21/16 Thidiazuron Risk Mitigation**  **Teleconference: Meeting Notes** 

**EPA attendance:** Khue Nguyen (PRD) , Christina Motilall (PRD) , Melissa Grable (PRD) , Mark Corbin (EFED) , Stephen Carey (EFED) , Bill Eckel (EFED) , Kathryn Montague (RD) , Steve Smearman (BEAD) , Sunil Ratnayake (BEAD), Monisha Kaul (BEAD) **Industry attendance (via teleconference)**  **:** Danielle Larochelle (Nufarm), Jamin Huang (Bayer), Trish Sheehy (Adama), Rodney Akers (Arysta), Ch ris Mason (Loveland), Eric Henry (Bayer), Brad Glenn (Bayer), Alex Niko lakis (Bayer)
**Notes:** EPA was supportive of thidiazuron’s continued registration as it was a chemical with low risks and high benefits. EPA was primarily interested in addressing spray drift risk to certain sensitive dicots (ex. lettuce). EPA proposed via email correspondence (dated 1/13/16) the following proposed risk mitigation measures for the thidiazuron labels, with the goal of achieving greater protection from spray drift and more parity between all the different labels:

1. No aerial application wi thin 0.5 miles of lettuce (this language already appears on some labels) 2. No aerial application within 5 miles upwind of citrus in flush (this language already appears on some labels) 3. No ground application within 100 feet of lettuce (this language already appears on some labels) 4. No ground application within 0.5 miles upwind from citrus (this language already appears on some labels) 5. Apply with medium or coarser spray (according to ASAE standard 572) for standard nozzles for both aerial and ground applications (this language already appears on some labels) 6. When using ground application, apply with nozzle height no more than 2 feet above the ground or crop canopy (this language already appears on some labels) 7. Mixtures with organophosphates can increase non

-target crop phytotoxicity. Additional care should be exercised when lettuce, citrus, cantaloupes or any other edible crops are adjacent to treated cotton fields (this language already appears on some labels). 8. Maximum application rate of 0.3 pounds of active ingredient per acre per year (this was RED risk mitigation, this language already appears on most labels, all registrants need to check that this appears on their label). 9. Maximum of 2 applications, but not to exceed 0.3 pounds of active ingredient per acre per year (this language already appears on some labels) 10. Minimum retreatment interval of 21 days (this language already appears on some labels)

Industry unanimously agreed to implement measures 1

-9, but had comments on item number 10. Nufarm was concerned about the 21

-day minimum retreatment interval (MRI) restriction and thought it was unjustified for several reasons: 1) the 21 day MRI requirement that appears on some thidiazuron labels was for products co

formulated with diuron and was meant to satisfy the diuron RED requirements 2) the thidiazuron RED did not specify a requirement for a 21

- day MRI3) the 21

-day MRI restriction interferes with situations where two successive applications of

thidiazuron are needed to ensure adequate defoliation. Often a second application of defoliant is applied approximately 7 days after the first application. 4) The 21

-day MRI restriction is not supported by current dissipation data for thidiazuron

There was some discussion about the single application rate of thidiazuron, the maximum application rate of thidiazuron, and the thidiazuron application rates on thidiazuron/diuron labels and how it related to the 21

- day MRI restriction, but it was difficult to understand over the phone

. EPA suggested that N ufarm submit comments via email so EPA could fully review. Nufarm agreed to submit comments separately via email. EPA stated it would follow up regarding item 10 once it had a chance to review comments. EPA discussed next steps for thidiazuron. EPA inte nded to publish the proposed interim decision for public comment in March 2016. EPA intended to require the full suite of pollinator data for thidiazuron in a GDCI to be issued in the near future, noting that industry would not have to initiate tier 2 and tier 3 pollinator testing until EPA had completed tier 1 pollinator screening and given notice that tier 2 and tier 3 data were required. Industry thought that additional pollinator data were unjustified since current data indicates that thidiazuron is not very toxic to bees. EPA said that requiring additional pollinator data was consistent with its new policy for pollinator risk assessment

. T hidiazuron was among a list of many chemicals with additional pollinator data requirements. In addition, expos ure to pollinators could not be precluded because cotton flowering was intermittent and some flower buds may still be open during thidiazuron application. The meeting was subsequently disbanded.