The Pest Management Regulatory Agency has approved the full registration of Maestro 80 DF (captan) fungicide for control of rhizoctonia root rot (Rhizoctonia solani), pythium root rot and damping-off (Pythium spp.), phytophthora root rot (Phytophthora cactorum) and grey mould (Botrytis cinerea) and suppression of cylindrocarpon root rot (Cylindrocarpon destructans) of ginseng. Many thanks to Jim Chaput, Provincial Minor Use Coordinator, OMAF and MRA, Arysta LifeScience North America, and the AAFC Pest Management Centre for securing this registration.
Apply MAESTRO 80DF as a broadcast foliar spray at a rate of 2.5 kg/ha (2.0 kg a.i./ha) in a spray volume of 935 – 1871 L water/ha. Begin applications prior to disease onset, when conditions are conducive to disease development with a minimum interval of 7 days. Do not apply more than 8 applications. Ground applications only. Applications can be made up to 20 days before harvest.
The application rate should be based on 2.5 kg product per hectare applied in the appropriate volume of carrier to achieve thorough coverage of all plant surfaces. For example, if you apply 1000 litres of water per hectare, thoroughly mix 2.5 kg of product in 1000 litres of water and apply thorough coverage of all above-ground plant surfaces for optimal disease control. Use care in mixing and application to avoid exceeding rates of 2.5 kg product per hectare regardless of spray volume.
DO NOT re-enter treated ginseng areas within 5 days of application for scouting, 25 days for any hand-set irrigation activities, and 48 hours for all other activities.
Conditions are conducive to the development of foliar Phytophthora at this time. 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 new label, please contact Arysta LifeScience North America or the Ontario Ginseng Growers Association.