Potato Review

BP2019 years. We need to know whether there are other factors responsible,” he said. There are obvious differences in the 2019 season, including higher than average air temperatures and high-intensity rainfall contributing to the epidemic on the Ayrshire-based Auchincruive Estate where trials were taking place. Dr Bain said blight risk is higher at an average temperature of 21 o C compared with 16 o C while the weathering/rain-fastness of fungicide products will also have been tested very thoroughly in 2019. He said rainfall in Ayrshire in August was more than twice the normal amount. However, he emphasised, it could be that the third difference in 2019 may be the most significant. Samples of P. infestans from the site have been genotyped by the James Hutton Bi-annual potato show draws in crowds, as it showcases all the industry has to offer and tackles the latest challenges and concerns. Heather Briggs reports. BP2019 10 POTATO REVIEW JANUARY/FEBRUARY 2020 C hallenges and concerns, such as threats from aggressive late blight, aphids and virus were all put under the spotlight at BP2019, with some seminars so packed that there was standing room only. Agronomists, scientists and industry specialists shared their expert opinions and demonstrated their work at the show’s many trade stands. A poster on the SRUC stand questioned whether the risk of tuber blight could be a significant barrier to the industry’s uptake of Integrated Pest Management (IPM). Dr Ruairidh Bain, specialist potato blight researcher at SRUC, told us that at SRUC’s potato blight trial site this year the disease proved to be particularly difficult to control in the last two or three weeks of August. “Of course the weather was very favourable for blight, with prolonged high-risk conditions (temperature and relative humidity). However, we’ve had such conditions in many previous Institute and there is mainly natural infection by the new genotype 36_A2. Information to date indicates that this genotype is associated with high aggressiveness, he said. “The presence of 36_A2 may explain, at least in part, why the general level of control at the site this year has not been as good as anticipated.” There is no evidence from the trial site of any fungicide resistance issues, he said. “We are raising awareness, but we are not confirming that 36_A2 will make control more difficult in crops in future. This is because it’s impossible to separate out the individual effects of the number of Hutton Periods, the amount of rainfall, the higher air temperatures and P. infestans genotype.