19 August 2022
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Update from David Cooke and the FAB team at the James Hutton Institute.
THANKS to all scouts who have found and submitted samples of late blight this season. Each scout has been updated on their own samples, but this is an update to the whole FAB scout team on the findings to date in this exceptionally warm, dry 2022 season.
The FAB mapping site is now available and shows the 37 outbreaks reported to date from across Britain (https://blight.hutton.ac.uk/BlightReport). The first outbreak was reported from Cornwall in mid-March with four more in May from Cornwall, Kent and north and south Wales. Slightly more favourable conditions for blight occurred locally in June and 13 outbreaks were reported from across England and Wales. Despite the very dry conditions in July, another 13 outbreaks were reported and a further seven to date in August. Seven outbreaks remain unconfirmed or negative due to either very dry lesions or sample degradation in the post. Late blight was formally confirmed in Scotland for the first time in August as prior samples were dried up.
Genotyping of 127 samples of Phytophthora infestans from 26 outbreaks indicates over 50% are of genotype 6_A1 with almost 30% of 36_A2, 6% of 37_A2 and 9% being ‘Other’ genotypes. The higher prevalence of 6_A1 than in 2021 (24%) is due to a higher frequency of sampled outbreaks in western than eastern potato growing regions. Genotype 36_A2 has been sampled in Kent, Cheshire, Merseyside, Norfolk, Shropshire and north Wales. The presence of 37_A2 in two outbreaks in Cheshire is a reminder of the need to follow current best practice in use of fluazinam.
We regret to report that the FAB registration and submission system on the website is not yet functional; work is ongoing and an update on this is planned in late August. Nonetheless, we encourage scouts to continue to submit samples from crops and volunteer potatoes to get a full indication of the 2022 pathogen population. Please include lesions pressed onto the FTA cards to ensure genotypes can be recovered from pathogen DNA. If you have not received a sample pack, or need new packs, then please contact us ([email protected]). In the coming weeks, the team at Hutton will be screening a selection of contemporary isolates against key fungicide active ingredients.
