I have recently become very interested in plant pathogens. Here I will document the different species I see
in Ireland, organised by month. I hope this site will be a useful resource, both as a reference and to inspire people to take notice
of these underappreciated organisms. They are incredibly diverse in form and ecology, and are so ubiquitous that they cannot be ignored.
I originally was only recording fungi and oomycetes but have since expanded to all gall-forming organisms.
In 2025 I am working on an Irish Naturalists’ Journal-funded project called Recording the plant-pathogenic fungi and oomycetes of Ireland.
Find out more on the project page here.
New species to Ireland
(twenty-seven fungi,
seven oomycetes,
two mites,
two midges,
an aphid, and
a nematode as of
16/02/2025)
3rd June 2020 Microbotryum coronariae on
Silene (Lychnis) flos-cuculi
in Lagan Meadows, Belfast. This one appears to be rather rare with less than fifteen
records from Britain.
24th July 2020 Microbotryum lagerheimii on
Silene uniflora
on the Sheepland Coast, Down. I'm not 100% sure this isn't actually
M. silenes-inflatae but new either way.
25th August 2023 Aceria euphrasiae on
Euphrasia sp.
at Killard Point, Down. I will try and find a specimen next summer to check for
living mites but I am pretty confident about this. With one British record, it seems
to be genuinely rare globally.
9th-10th April 2024 Mycosphaerellaceae sp. on
Escallonia sp.
in North Down.
Note both Septoria escalloniae and Mycosphaerella escalloniae
are known from this host, and can only be distinguished microscopically (I'll get round to it eventually...).
21st April 2024 Urocystis primulae on
Primula vulgaris
at Killard Point.
Note the white conidia around the anthers and the black spore mass in the ovary.
2nd July 2024 Septoria anthyllidicola on
Anthyllis vulneraria
in our garden in East Belfast.
Note the small, dark pycnidia (fruiting bodies in the leaf tissue) which have burst open to release conidia.
This species has not been previously recorded in Britain or Ireland, so it was a particularly exciting find.
Septoria has recently been discovered to be far less host-specific than previously thought (Verkley et al., 2013)
so it may be lumped into another species.
9th-10th July 2024 Pucciniastrum on
Soleirolia soleirolii
in Acaill, Mayo. This taxon was discovered by Chris Preston in Cambridgeshire.
Its identity is unknown - see
Preston, C. D., Harries, D. J., & Stringer, R. N. (2023). A newly discovered rust on Soleirolia soleirolii. Field Mycology, 24(1), 13–17.
10th July 2024 Entyloma on
Ranunculus baudotii
in an Caol, Acaill, Mayo.
This is an undescribed Entyloma species in the Entyloma eburneum complex.
This group has not been recorded on R. baudotii before so it may be new to science,
or it could be the same species as infects other Water Crowfoots. The species on Crowfoots
haven't been studied yet so its taxonomy remains unclear.
11th July 2024 Septoria on
Bellis perennis
in Bun an Churraigh, Acaill, Mayo.
There are two species of Septoria on Bellis perennis according to Unamuno (1942):
Septoria bellidis - spores up to 35μm
Septoria bellidicola - spores 72–104 × 1.5–2.5μm
This one has spores around 50–60μm so it's unclear if it is either.
Septoria has been discovered to be far less host-specific than previously thought (Verkley et al., 2013)
so no matter what it is, it will probably be lumped into something else eventually.
15th July 2024 Peronospora sparsa on
Rubus fruticosus agg.
in Tyrone.
Note some authors consider Peronospora on Rubus to be a separate species (P. rubi).
20th July 2024 Puccinia asperulae-odoratae on
Galium odoratum
in Black Mountain, Belfast.
This is often considered a junior synonym of the widespread P. punctata which has been found in Ireland previously.
25th July 2024 Septoria posoniensis on
Chrysosplenium oppositifolium
in Cregagh Glen.
There are only three previous records on this host, but the spore size matches the description from other Chrysosplenium species.
26th July 2024 Erysiphe akebiae on
Akebia quinata
in Botanic Gardens, Belfast.
This is probably a recent introduction as there are no British records before 2002.
28th July 2024 Leptosphaerulina myrtillina on
Vaccinium myrtillus
in Cottage Farm, Tyrone.
This one is definitely extremely common - I remember seeing it in the Mournes before.
27th August and 13th September 2024 Cecidophyopsis atrichus on
Rabalera holostea (left) and Stellaria graminea (right)
in Down.
This mite seems to be rather underrecorded.
3rd September 2024 Dasineura "B" sensu Harris on
Filipendula ulmaria
in Derry.
An undescribed Dasineura gall midge. It is apparently common in Britain. Thanks to sk53 on iNaturalist for ID.
8th September 2024 Contarinia dipsacearum on
Succisa pratensis
at Murlough NNR, Down.
One or several larvae sit at the base of an unopened flower. The tell-tale sign is
that galled flowers are surrounded by open flowers, as if they should also be open.
There is only a single other record for this species from Ireland or Britain,
from London in 1947. It is apparently genuinely rare, though the subtle
symptoms means these flower-galling Dasineura are easily overlooked.
Published as Dalzell, J. (2025). Contarinia dipsacearum Rübsaamen, 1921, a gall midge (Diptera:
Cecidomyiidae) new to Ireland and its overlooked occurrence in Britain. Irish
Naturalists’ Journal, 41 (in press).
13th September 2024 Subanguina graminophila on
Agrostis stolonifera
at Lagan Meadows, Belfast.
A nematode gall. There are very few global records but it is probably extremely underrecorded.
Within a week I found it at two other sites so it is probably widespread and common in Ireland.
We (Thomas Fleming at AFBI and I) have barcoded this to confirm its identity — paper on the way.
20th September 2024 Peronospora trifolii-repentis on
Trifolium repens
in Ballymorran.
This one appears to be genuinely rare. I had been looking for it fairly intensively all year!
Then again the symptoms are very subtle and probably easily overlooked, even when searching for it.
11th October 2024 Pseudophaeophleospora atkinsonii on
Veronica (Hebe) salicifolia
in a garden in East Belfast. This species is from New Zealand like its host. It has distinctively brown conidia.
24th October 2024 Entyloma ranunculacearum on
Ranunculus acris
beside a lowland raised bog near Randalstown, Antrim.
Another species in the hyperdiverse Entyloma eburneum complex which infects many species of Ranunculus.
16th November 2024 Peronospora sp. on
Veronica (Hebe) speciosa
in a garden at Ballyhornan, Down. This is usually recorded as Peronospora grisea
but is actually one of the many undescribed species infecting Veronica (Thines & Choi, 2016).
15th February 2025 Synchytrium globosum on
Galium odoratum
in Cregagh Glen, Belfast.
This genus has a confusing taxonomy that hasn't been revised in the age of
genetic sequencing and phylogeny. There are many highly host-specific species and a few
generalists, often with similar/identical morphology.
This one is a generalist, but I suspect genetic work would uncover
cryptic diversity. This is as far as I can tell the first global record for it on
Galium odoratum, but it is known from other species in the same genus.
Thines, M., & Choi, Y.-J. (2016).
Evolution, Diversity, and Taxonomy of the Peronosporaceae,
with Focus on the Genus Peronospora. Phytopathology,
106(1), 6–18.
https://doi.org/10.1094/PHYTO-05-15-0127-RVW
