Potato Review

28 POTATO REVIEW NOVEMBER/DECEMBER 2022 VIRUS CONTROL T HE Scottish seed potato industry has for many decades supplied high quality seed potatoes to multiple countries around the world. However, the increasingly unpredictable climate is triggering a new set of challenges to the industry, where milder summers and winters are leading to an increasing risk of virus transmission in seed crops. e 2022 growing season has been both warmer and drier than average in the majority of the seed potato growing areas in Scotland. Despite this, tuber numbers on heavier land appear to be around average in many varieties, though lighter land has su ered more from the lack of moisture. e exceptionally warm weather around the end of July and early August slowed tuber growth rates, with some crops being desiccated around seven to 14 days later than was originally planned. is is where the risk lies, as any extension to the growing season signi cantly increases the likelihood of virus acquisition from the surrounding environment, where aphids are present in the crop. Peach potato aphids caught in the suction traps at Dundee and Edinburgh have been well above the 10-year average this summer. Data from the wider network of yellow water traps indicates peach potato aphids were being found in high numbers across a wide geographical area of Scotland, including Grampian, where vector pressure was three times the seasonal average. Peach potato aphids are a vector of both PVY and potato leaf roll virus (PLRV) and present a signi cant risk to early generation seed where control is challenged by an aphid “biological arms race” and withdrawal of chemistry. Strategy trials To tackle this challenge, growers need to be looking increasingly to using Integrated Pest Management (IPM) strategies alongside plant protection products to maintain quality seed. Scottish Agronomy andMcCain Potatoes, have been leading trials on IPMstrategies for the seed industry, including the use of strawmulch which has had signi cant outcomes. In 2021, trials in Fife had very high pressure fromcolonising aphids, predominantly potato aphids but also frompeach potato aphids. e results showed 40% control of PVYNwas achieved and 59% control of PLRV fromusing strawmulch alone. Donald Paterson of Scottish Agronomy talks about some positive results seen so far with ongoing trials on IPM strategies in Scottish seed potatoes. IPM R&D pipeline proving vital to virus control DONALD PATERSON Donald Paterson specialises in both cereal and potato agronomy at Scottish Agronomy. He co-runs group agronomy meetings as well as carrying out crop walking for farmer members on a one-to-one basis. Donald worked previously on the trials team, and still enjoys helping out with sowing and harvest at the busy times of year.