Plasmopara euphrasiae: a downy mildew species new to Ireland

Slievenacloy Nature Reserve is an Ulster Wildlife reserve in Antrim. It is very well managed for upland grassland, with a wealth of Devil’s-Bit dominated grassland. I was there for the first time ever on the eleventh of August, and was very impressed by how rich and large the reserve is.

In one of the fields on the reserve I found a small, whitish mould growing on an Eyebright (IDed to Euphrasia arctica/confusa/nemorosa agg., but too old to ID to species). Since I have recently become interested in plant parasites I took a sample home. I identified it using the extremely useful resource I was surprised to discover it is a species never before recorded in Ireland, Plasmopara euphrasiae.

Plasmopara euphrasiae under the microscope

There are old records of a related species, Plasmopara densa, from before the two species were split – since some of these were found on Eyebright, they can be redetermined as P. euphrasiae, but this is the first known record of this species in Ireland. (In fact as I was writing this I found one, from Braganstown, Louth, in 1895).

Many thanks to Chris Preston for inspiring and encouraging my interest in plant parasites and for verifying the ID.





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