Fungal Plant Parasites

[Chris Yeates]

hello all

I have been thinking about starting this thread for a while, and have been spurred into action by Lancashire Lad's post about rust on Dog Rose.

Unfortunately that is a case where (as so often in the study of fungi) one needs access to a microscope. However, the good news is that when it comes to groups such as the rusts, smuts, powdery and downy mildews etc. this is often not the case - in fact a much higher proportion can be confidently named to species without microscopic examination than is the case with agarics, brackets and the like.

All one needs is a good botanical knowledge and a handlens. Someone like KeenTeen would be perfectly equipped to make exciting discoveries, and I know there are many WABbers who know their British plants very well. In addition it adds another string to ones mycological (and indeed botanical) bow when you are out and about. A lot of these parasites are most successful when their hosts are stressed, and patches of waste ground in the middle of towns and cities can turn up very interesting finds.

I am kicking off here with a rust on Pignut which I found yesterday. on checking the records it appears to be rare, but that might well be because not a lot of people are aware of such things. There are two rusts on this host, this aecial 'cluster-cup' stage and another one which doesn't distort the host in this way and has chocolate coloured spores Puccinia tumida.

In the strange way of things this species, Puccinia bistortae also has a chocolate coloured stage but on a completely unrelated host - Common Bistort. Sometimes the two species can be found on the same leaf, and it was through the experimental work of a late 19th century amateur Yorkshire mycologist, Henry Thomas Soppitt, that the true picture emerged - the logical thought being that the rusts on the Pignut must be one thing and that on the Bistort another.


Trust me, in general the picture is much more straightforward. If someone says to me "I have seen the chocolate rust on Bistort" I know exactly what they mean and can give them the species name.

I shall regularly post here on this thread and will make sure that what I post is what is around at the time (at least in Yorkshire and that is fairly central in British terms). I'll try to give hints on identification, things to look out for etc. and will in general not include anything which cannot be identified in the field. I'll happily look at anything people have photographed/collected and do my best to name them (a useful hint is that these fungi scan well and that is sometimes by far the easiest way to 'photograph' them). I will put all the species I post on the A to Z.

Finally I promise that in future I shall not ramble on at this length - this should be thought of as less of a ramble than a preamble.

cheers

Chris

[flaxton]

My garden is covered in pignut so I will look out for any rust

Mal

[KeenTeen17]

Thanks for the mention Chris. I'll check all the plants I see now for rusts etc. If I did post pictures would they be easy to identify?

[FungiJohn]

Look out now for these:

BlueBell Rust - Uromyces muscari



Bramble Stem Rust - Kuehneola uredinis



Nettle Rust - Puccinia urticata



and Calloria neglecta on the dead stems of nettles



to name just a few

John

[poschiavanus]

Good thread Chris.

Others to catch around now: photos not to hand.

• on Lesser Celandine. There are 3-4 rusts, but one forms smallish spots visible on the top of the leaves, and a characteristic rust coloured spot on the underside (Uromyces dactylidis).
• Sweet Violet. a couple of rusts, but the one I've seen recently on leaves and petioles was Puccinia violae.
• Oregon Grape. Mahonia rust Cumminsella mirabilissima. Look for leaves discoloured a darkish burgundy colour. Turn them over and the underside of the leaf will have a rusty felted appearance.
• Meadowsweet: a bit early yet, but this is a spectacular (and under-recorded) rust. Probably occurs everywhere Meadowsweet grows.

All of these are gall causers as well.

posch

[KeenTeen17]

wow this is quite fascinating I'll check all the bluebells, brambles & nettles

[Chris Yeates]

this response is very gratifying - thanks everyone

this one is very common and should be fairly easily found by anyone looking at the hosts - Puccinia lagenophorae:




It was originally described by M.C. Cooke from leaves of Lagenophora collected at Omeo, a small historic gold-mining pioneering town on the edge of the Snowy Mountains in Victoria, Australia. It was unknown in Europe until its discovery in 1961. In that year it turned up in France and was discovered by Dr R.W.G. Dennis of Kew at Dungeness in Kent. By the following year it was found in SW England from Sothampton to the Lizard, in Wales and in the Scillies. It is unlikely that such a striking fungus had been overlooked before that time.

In Britain and Ireland it is very common on Senecio squalidus (Oxford Ragwort) and Senecio vulgaris (Common Groundsel - including the latter’s radiate form); it is very rare on Senecio cambrensis (1 record?) and has been recorded (again rarely), on a number of related species in other genera but we don’t need to go there in what is intended to be an introduction to this area.

There is another rust which attacks Oxford Ragwort and Common Groundsel, Coleosporium tussilaginis but that never has the “cluster-cups” which can be seen here, with their pale outer rings; it forms more shapeless areas of attack, and in addition it tends to occur chiefly on the underside of the leaves.

P. lagenophorae sometimes attacks its host so successfully that it becomes a contorted mass of stems and leaves:


best wishes and good hunting

Chris

[Chris Yeates]

Originally Posted by poschiavanus

Good thread Chris.
. . . [*]Oregon Grape. Mahonia rust Cumminsella mirabilissima. Look for leaves discoloured a darkish burgundy colour. Turn them over and the underside of the leaf will have a rusty felted appearance. . . .

posch

A good one at this time Posch!

A North American species, Cumminsiella mirabilissima was first reported from Scotland in 1922 (near Edinburgh); the first published record from England was from Northumberland in 1930 (it had already been reported from Wales in 1926).



It is now widespread on Oregon Grape Mahonia aquifolium, and has also been recorded on M. bealei - I have never seen it on the latter. Posch's description is very good; here are uredospores and teliospores of this species - the long pedicels (stems) to the teliospores are very distinctive:



as regards the name - Cumminsiella mirabilissima - it's rather operatic I feel (try singing it to the tune of "La donna è mobile" from Verdi's Rigoletto)

YouTube - Luciano Pavarotti - La Donna È Mobile



cheers

Chris

[Tiggrx]

I saw a rust on the leaf-stalks of Sweet Cicely last week - would this be Puccinia chaerophylli or are there other likely contenders? I have a (poor) photo which I could post if it would be of interest.

[Chris Yeates]

Originally Posted by Tiggrx

I saw a rust on the leaf-stalks of Sweet Cicely last week - would this be Puccinia chaerophylli or are there other likely contenders? I have a (poor) photo which I could post if it would be of interest.

Absolutely Tiggrx

this is one I shall feature shortly; it's interesting that up here in Yorkshire Puccinia chaerophylli is far more common on (the introduced) Myrrhis than on the native Cow Parsley - although Sweet Cicely would appear to be a native species unless one knew different.

best wishes

Chris