Effective control of late blight in potatoes starts with choosing the right product at the right growth stage. A fungicide like Ridomil Gold MZ is best utilised during periods of rapid canopy growth as the fully systemic nature of this product offers up to 14 days protection of new growth after application.

Ridomil Gold MZ contains mefenoxam plus mancozeb in one convenient formulation for built-in resistance management. The active ingredient, metalaxyl, is in the form of mefenoxam which gives Ridomil Gold MZ twice the activity of traditional metalaxyl. This means only half the usual amount of metalaxyl is required, reducing chemical residue and the environmental footprint.

When the canopy growth begins to slow, Raeleen Watherston, Syngenta Territory Manager for upper North Island, recommends Revus as a good option to use for preventative late blight control. “Once Revus has dried on the leaf it is fully rainfast, binding strongly onto the leaf’s waxy layer and gradually moving into the leaf for reliable disease control without the risk of wash-off,” Raeleen says.

The active ingredient in Revus (mandipropamid) is one of the most effective products listed in the EuroBlight late blight fungicide table for potatoes, with a score of 4 for leaf blight control on a scale of 2-5 and the maximum of 3 stars for rainfastness on a scale of 1-3.

Revus can be mixed with Amistar, Score or the new SDHI fungicide Miravis, for early blight control if required. It’s recommended to use angled Defy 3D nozzles to improve the coverage and penetration of fungicides into the canopy, with water rates of 250 to 300 L/ha for applications after row closure.

For more information on Ridomil Gold MZ and Revus, and how to get free Defy 3D nozzles, contact your Fruitfed Supplies Technical Horticultural Representative.