Orondis Gold fungicide was recently registered for the control of Phytophthora root rot on ginseng. Orondis (oxathiapiprolin) is a fungicide in a new group that has been shown to be highly effective at controlling Phytophthora. It will not move down from the leaves to the roots, so must be applied to the root zone to control Phytophthora root rot. This will require application with a high water volume to get it into the straw followed by irrigation or rainfall to wash it into the root zone.
Although it is highly effective, Orondis is also highly susceptible to the development of resistance. If Phytophthora becomes resistant to Orondis in even one field, it will spread to the whole industry and Orondis will no longer be effective. As a result, it is being sold as a co-pack with Ridomil. Orondis Gold is a co-pack consisting of Orondis Gold A (oxathiapiprolin) and Orondis Gold B (metalaxyl-M). The two components MUST be applied together. Mixing procedures indicated on the label should be followed exactly so they remain in solution in the spray tank. Mixing the products the wrong way can result in the chemicals coming out of solution and plugging up the sprayer.
Orondis Gold should be applied as a protectant fungicide prior to the onset of disease. Due to limited supply and the need to manage resistance, Syngenta is mandating a maximum of one application of Orondis Gold per season on ginseng. The optimal time to apply the product is as the first application for Phytophthora in the spring prior to unfolding of the leaves. Unfolded leaves will catch the spray, resulting in less penetration into the straw. Orondis Gold would replace the first Ridomil application. This would also use up one of the permitted three applications of Ridomil per season. Since Phytophthora is not usually an issue in seedling gardens, application of Orondis Gold to seedlings is not necessary. The product should be applied at a high water volume (2500 L/ha) to ensure penetration of the product into the straw. Application should be immediately followed by overhead irrigation and/or rainfall of at least 7 mm to wash it into the root zone.
It is very important for growers to be careful with this product to ensure that resistance does not develop in the Phytophthora. One grower using it improperly could lead to resistance that will then spread to the entire industry. Never apply oxathiapiprolin on its own and always rotate the product with at least two other Phytophthora products.
For more information and further application instructions refer to the Orondis Gold A and Orondis Gold B labels or consult the Syngenta Canada website at Syngenta.ca.