Potato Review

www.potatoreview.com POTATO REVIEW JULY/AUGUST 2021 31 BLIGHT STRATEGIES the starting gun on this year’s blight epidemic, where the inoculum is present. Craig says the threat is more likely to stem from the perennial challenge of waste dumps, and taking a preventative approach to blight control in the early phases of the programme will provide growers with greater exibility later in the season. He said: “Using a product with curative and proven activity against stem blight early is essential in order to establish a clean base for the crop ahead of the stable canopy phase. In Zorvec Endavia, systemic movement into new growth provides protection during the rapid growth phase of the crop, further ensuring that essential clean start, with no blight lesions continuing to sporulate lower in the canopy. “ e focus is going to be on the interval between sprays and that will be in uenced by the nature of the threat, and by weather conditions – not ignoring practical challenges such as sprayer capacity, crop area and travel time.” Craig said the oxathiapiprolin-based chemistry found in Zorvec Endavia has been instrumental in meeting growers’ needs. Two applications in the rapid growth phase provide a base on which to build an e ective programme, with robust protection for 10 days versus the industry-standard seven, meaning if weather prevents sprayers from travelling, or capacity restricts visits to more distant crops, they will still be protected. In addition, its curative properties also deliver kickback on any latent disease in the crop, he added. Craig said: “Even as late blight becomes increasingly aggressive and resistance or reduced sensitivity to some actives becomes more common, Zorvec applied at the rapid growth phase will deliver exceptional curative and protectant activity on stem and foliar blight.” Once an infection is present, the cost of trying to keep it under control is considerable, therefore opting for a product and programme which is more e ective early in the season will save money in the long term. “Two applications of Zorvec over three weeks will enable growers to return to their regular seven-day spray schedule while freeing up a day for other critical activities, at a high-pressure time on farm, such as irrigation scheduling,” said Craig. “With up to four applications of Zorvec permitted on the potato crop, growers still retain the exibility for one to two applications during the stable canopy when disease pressure and spray interval pressure may increase further.” He said this not only buys time, but being unique in group 49 as described by FRAC, enables users to deploy a wider range of di ering modes of action across the programme to maintain the value of all the chemistry available to deploy against late blight. “Resistance to some active ingredients means they are e ectively redundant. The phenylamides are one example, while strains with insensitivity to fluazinam (33_A2 and 37_A2) limit its ecacy.” “Using a product with curative and proven activity against stem blight early is essential in order to establish a clean base for the crop ahead of the stable canopy phase.” Wet potatoes Northants