Re-evaluation Note REV2012-01, Update on the Use of Phorate on Potatoes

Pest Management Regulatory Agency
28 May 2012
ISSN: 1925-0649 (PDF version)
Catalogue number: H113-5/2012-1E-PDF (PDF version)

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In May 2004, Health Canada's Pest Management Regulatory Agency (PMRA) published the Re-evaluation Decision Document RRD2004-11, Phorate. Based on risks to birds, mammals and aquatic organisms from exposure to the granular product, the PMRA made the regulatory decision to phase out the sale and use of Thimet 15-G Soil & Systemic Insecticide Granular. Uses of phorate and associated end-use products on corn, lettuce, beans and rutabagas were discontinued. Due to a lack of alternatives for the control of wireworm in potatoes, the phase-out of Thimet 15-G for use on potatoes had subsequently been extended until 1 August 2012. This extension allowed for effective control of wireworm in potato crops during the development and implementation of a transition strategy for the management of this pest.

This Re-evaluation Note presents a further extension to the phorate phase-out schedule as well as a summary of additional mitigation measures initiated to further manage exposure to the granular product.

The wireworm problem on potatoes continues to be extensive, with populations increasing in all potato growing areas. Presently, there are no suitable alternatives available to address wireworm on potatoes. Therefore, the registration has been extended for a period of three years, to allow time for additional research and the potential registration of alternatives to phorate. Additional time (up to two years) may be added to the phase-out schedule to allow time for the registration of alternatives if applications are received within the initial three year period, otherwise the phase-out will proceed according to the following schedule:

• Last date of sale of Thimet 15-G by registrant - 31 December 2014
• Last date of sale of Thimet 15-G by retailers and distributors - 1 May 2015
• Last date of use of Thimet 15-G by growers & users - 1 August 2015

Wireworms are long-lived beetle larvae that may cause severe damage in first year potatoes planted following grains or fallow. Exposure to wireworms results in significant decreases in marketability of potatoes. The loss of phorate without a suitable replacement would have a large economic impact, particularly in Alberta and Prince Edward Island.

Alternative pest management strategies are currently under development by a Phorate Transition Strategy Working Group comprised of growers and grower associations, provincial government representatives, registrants and other federal government departments, including  Agriculture and Agri-Food Canada. The PMRA is coordinating and facilitating this working group.

The Transition Strategy Working Group is working to:

1. promote agricultural practices that will decrease the likelihood of wireworm infestations, thereby decreasing reliance on phorate, and
2. identify a potential alternative and support research to aid the registration of products to replace phorate use in potato.

Currently there are a number of research projects underway, including studies on control of wireworm populations through crop rotations and trials on efficacy of various pesticide product combinations. In addition, research is being conducted on the adult form, click beetles. The  Canadian Potato Council has identified wireworm as a top priority for potato research funding, and has indicated that they will share the cost of research with Agriculture and Agri-Food Canada in 2012.

The extension of the phase-out period for Thimet 15-G Soil & Systemic Insecticide Granular is subject to certain new conditions. The registrant will be required to: make additional label changes; expand their existing stewardship program to include risk mitigation for birds; and, implement other additional risk management measures. Monitoring the appropriate use of Thimet 15-G will be identified as a high priority for the PMRA's compliance activities.

A key risk management measure is the change requiring that all purchasers and applicators of this product be provincially certified/licensed pesticide applicators.

A number of changes will be made to the label in an effort to address environmental risk. The label will identify the requirement that all purchasers and users be provincially certified/licensed pesticide applicators, corresponding to the previously stated risk management measure. In addition, a section of the label will be designated to identify risks to birds, and additional ways of managing these risks. A reference to the PMRA Incident Reporting System will be made on the label and minimum row spacing requirements will be indicated on the label to limit the maximum application rate. The label will also be updated to emphasize proper application methods. The registrant's product stewardship program will be expanded to include education about risk mitigation for birds via additions to the existing fact sheets. These changes include outlining of appropriate handling and application methods and encouragement to scout for wireworm tto ensure pesticide application is necessary.