A Year of Plant Pathogens

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.

New species to Ireland (eleven as of 14/07/2024)

30^th March 2024
Ramularia septata on Galanthus cf. nivalis from Orangefield Park.

9^th-10^th 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.

12^th April 2024
Albugo leimonios on Cardamine pratensis in Clement Wilson Park in the Lagan Valley.

12^th April 2024
Entyloma fumariae on Fumaria sp. in the Lagan Valley.

21^st 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.

30^th June 2024
Peronospora fulva on Lathyrus pratensis in Moreland's Meadow, Lagan Valley.

2^nd 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.

9^th-10^th 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.

10^th July 2024
Pucciniastrum guttatum on Sherardia arvensis in an Caol, Acaill, Mayo.

10^th 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.

11^th 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.