Purpose

As described in the CORESTA Guide No. 1, Guidance Residue Levels (GRLs) have been developed by the CORESTA Agro-Chemical Advisory Committee (ACAC) to provide guidance to tobacco growers and those in the tobacco industry interested in the application of Crop Protection Agents (CPAs), in compliance with the implementation of Good Agricultural Practice (GAP) in tobacco production. GRLs have been used worldwide as a reference when buying and selling tobacco. New CPAs are continually developed, and GRLs will need to be established in the interest of promoting responsible tobacco production. Residue data from field trials complying with label instructions are an integral component of establishing new GRLs. In order to create new and reliable GRLs, CORESTA decided to conduct additional residue trials and launched the dedicated Agrochemical Residue Field Trials Task Force in 2012. In January 2016, the Task Force was changed to a Sub-Group as its work and activities were viewed as being long-term.

Organisation

Coordinator:  Makoto Sebata, Japan Tobacco Inc., Japan
makoto.sebata@jt.com
Secretary:  Matthew Vann, North Carolina State University, USA
matthew_vann@ncsu.edu
Others:  Trial Executors and Sub-Group members (accordingly to availability)

Meetings

• Vienna, Austria, June 30, 2012
• Sapporo, Japan, September 22, 2012
• Lexington, KY, USA, January 20, 2013
• Brufa di Torgiano, Italy, October 12, 2013
• Raleigh, NC, USA, January 11, 2014
• Quebec, Canada, October 11, 2014
• Izmir, Turkey, October 24, 2015
• Berlin, Germany, October 8, 2016
• Santa Cruz do Sul, Brazil, October 21, 2017
• Kunming, China, October 21, 2018
• Victoria Falls, Zimbabwe, October 12, 2019

Achievements in light of the five original objectives (as of February 2014)

1.  GRL Candidates

ACAC provided a priority list of 23 CPAs for which GRLs should be defined. This list was classified as 1^st generation candidates.

Field trials for 10 of the 1^st generation candidates were finished by the end of 2018, and results were submitted to ACAC in order to discuss new GRLs. Six CPAs were removed from Priority II and III categories due to little use in 2018.

A further eight GRL candidates (classified as 2^nd generation candidates) were introduced to the Sub-Group with a follow up request for executors to conduct field trials in 2018.

2^nd generation candidate list

A small number of field trials for Fluopicolide and Mandipropamid were already conducted from 2014 to 2018, thus some information is presently available.

Trials and residue analysis are on going in February 2023 and most parts are to be completed by the end of 2023.

2.  Formal protocol

Essential points of study design

• Duration: 3 years
• Number of trials: 3 replicates per location
• Planting conditions: Minimum 3 treated rows per treatment (leaf from central row sampled for analysis)
• Application:
  • Only 1 agrochemical tested compound per treatment plot (row)
  • Adjust the conditions of application to obtain the expected highest residue per the product label, taking into account:
    • Rate; highest label rate
    • Number of applications; highest according to the label
    • Application intervals; shortest according to the label but target harvest based on the product's labeled PHI
    • Pre harvest interval (PHI); Label instruction
• Sampling: 2 samples based upon stalk positions (one lower stalk sample and one upper stalk sample).

3.  Participants and tobacco type

• 28 executors from 18 countries
  • North & Central America: USA, Mexico, Cuba and Guatemala
  • South America: Argentina and Brazil
  • Asia: India, Indonesia and Thailand
  • Africa: Malawi and Zimbabwe
  • Europe & Oriental tobacco region: Germany, Italy, Bulgaria, Greece, North Macedonia and Turkey
• Tobacco type: 4 types
  • FCV, BLY, ORT, Dark air-cured (DAC) and Dark flue-cured (DFC)

4.  Collation of results under formal protocol

• From 2013 to 2015, more than 270 field trials from 25 executors in 17 countries have been conducted for 13 CPAs.
• Additional trial results were accumulated from 2016 to 2018 (RFT-136-CTR). In total, 426 field trials have carried out as of October 2019. 
• The results for 10 CPAs; Azoxystrobin, Difenoconazole, Indoxacarb, Propamocarb, Tebuconazole, Chlorantraniliprole, Triflumuron, Fenamidone, Flubendiamide, and Teflubenzuron were submitted to ACAC in order to discuss new GRLs.
• Trials for 2^nd generation candidates were launched in 2018 (RFT-207-CTR). The results will be compiled and submitted to ACAC in 2023.

5.  Collection of already available residue trial data

• Residue data from the field trials have been provided by CPA companies and organisations.
• Data on CPAs outside of GRL candidates could be used for the verification of the current GRL values and/or for the selection of further new GRL candidates.

General

Poster Presentation at University of Kentucky Burley Tobacco Tour, 13 August 2019

Updated November 2023