The Pest Management Regulatory Agency has approved an Emergency Use Registration for Maestro 80 DF (captan) fungicide for control of Phytophthora rot of ginseng. Many thanks are due to Jim Chaput, Provincial Minor Use Coordinator, OMAFRA, Arysta LifeScience North America, and the Ontario Ginseng Growers Association for their efforts in securing this Emergency Use Registration.
For the control of Phytophthora rot (Phytophthora cactorum) of ginseng, apply Maestro 80 DF as a broadcast foliar spray at a rate of 4.2 kg/ha (3.36 kg ai/ha) with a maximum of 4 applications in 2012 with a minimum interval of 7 days between applications. Ground application only. Applications can be made up to 16 days before harvest. This Emergency Use expires on December 31, 2012.
The application rate should be based on 4.2 kg/ha applied in the appropriate volume of carrier to achieve thorough coverage of all plant surfaces. For example, if you apply 1000 L water/ha, thoroughly mix 4.2 kg of product in 1000 L water and thoroughly cover all above-ground plant surfaces for optimal disease control. Use care in mixing and application to avoid exceeding rates of 4.2 kg product/ha regardless of spray volume.
Note: The Restricted Entry Interval (REI) for Maestro has been changed this year. Do not re-enter treated ginseng areas within 2 days of application for hand weeding, 5 days for scouting, and 16 days for any handset irrigation. If re-entry into treated areas is required, workers must wear long pants, long-sleeved shirt, chemical resistant gloves, work boots and goggles.
Maestro (captan) fungicide is the only registered product that can control Phytophthora in dead or dying tissues. This is essential for preventing sporulation in these tissues and preventing spread of the spores across and between gardens. It is also the only registered product proven to control Phytophthora root rot under high disease pressure. However, to avoid resistance developing in the pathogen to Maestro (captan), rotate Maestro with applications of Ridomil and Aliette. Ridomil and Aliette can provide good control of the root rot phase of Phytophthora, especially when disease pressure is reduced through a Maestro (captan) application.
Consult the Maestro (captan) label for complete application procedures. For a copy of the revised label, please contact Arysta LifeScience North America or the Ontario Ginseng Growers Association.