Potato Review

28 POTATO REVIEW MAY/JUNE 2020 BLIGHT Robust early blight programme advised “Growers will be on heightened alert after last summer’s period of significant blight pressure” Craig Chisholm “E ective systemic fungicides are needed to protect rapidly growing crops from the start of the programme.” Paul Goddard P otato experts are advocating a robust blight programme during the rapid growth phase of the crop as volunteers continue to pose a hidden threat. Concerns have been aired over the potential for large numbers of tubers left in the ground from 2019 emerging and acting as a reservoir for blight. With 2020 planting well underway, cold conditions so far have suppressed volunteer establishment but farmers are being advised to keep a close eye out for their appearance. Crop Production Specialist at Frontier, Dr Reuben Morris, says prevention is better than cure when it comes to late blight. He said: “Protecting the rapid growth phase of the crop is essential. Once you have blight in the crop it is extremely di cult to tackle and you’re ghting it all the way through the season. “Once the infection is there farmers face a signi cant investment to try and keep it under control, so going for a product and a programme which is more e ective early in the season will save money in the long run.” Experts o er views on control for this season while all advocate the need for heightening anti-resistance strategies. In 2019 blight pressure in England increased signi cantly in June, posing huge challenges to potato growers. Wet weather then hampered the progress of harvesting throughout the winter months, leaving a sizeable chunk of the 2019 crop seemingly abandoned. Despite quite a number of these having been rescued during the recent dry period, there is a larger than usual number of tubers left in elds. It is from these elds that Reuben feels any blight threat will come this year. He said: “Blight carries over from one year to the next in tubers, and if the tubers are in the ground rather than waste piles then the threat is unquanti able and potentially more widespread. “In general, where some elds haven’t been lifted – or lifting has been attempted – the ground has not been in a very good state. ese elds were often the last ones to be looked at for following crops this spring. Cover crops, while helping to restore soil structure, will not control volunteer potatoes. “Where tubers are still alive and the volunteers come up, that will be the source of the carryover of blight into this year.” Corteva AgriscienceTM says Zorvec Enicade® and its new co-formulated blight fungicide Zorvec Endavia® will give growers con dence that they can stay on top of the disease in 2020. Craig Chisholm, the company’s eld Technical Manager for potatoes, said growers have the option to be exible with applications but advises the product is most e ective when used preventatively during the rapid growth phase of the crop. “ e dry weather experienced by many in