Observation 222388: Rhytisma punctatum (Pers.) Fr.
When: 2015-10-25
No herbarium specimen

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Micro might not help
By: Byrain
2015-11-11 22:32:56 CST (-0500)

My understanding is that at around this time they will be overwintering and immature. Maybe someone at ascofrance will have a good reference or know someone working on them?

Freshly aware of the puzzle surrounding this group of species,
By: Andrew Khitsun (Andrew)
2015-11-11 21:55:14 CST (-0500)

I will concentrate on it next fall and pick up and photograph several specimens. The problem is usually to find someone willing and able to do microscopy to find out exactly what the species is :(

It could be unusual
By: Byrain
2015-11-11 21:33:30 CST (-0500)

simply because no one has been paying attention to where it was the preferred host until now. Either way, worth collecting and verifying the host in the future so that there is a good record of it. :)

It bothered me what you said about unusual host for this species.
By: Andrew Khitsun (Andrew)
2015-11-11 21:11:30 CST (-0500)

I regret that I didn’t take the full picture of the leaf, although at the time I made a note it’s A.saccharum. I looked up online and found list of species encountered at the location, among which are invasive Acer platanoides and also Acer saccharum and Acer rubrum. I went back, but with all the leaves down now it’s hard to tell what is where, and the massive prevalence of A.saccharum leaves buried everything else in its mass. It bothers me how the points of the leaf are so obtuse, not sharp, although some A.saccharum may look similar, but also can be A.rubrum. As far as I know A.platanoides is always pointy.

Reading some more, I did find other studies that state species of maple DO matter.
By: Andrew Khitsun (Andrew)
2015-11-10 22:58:28 CST (-0500)

Here is one of them , also reflecting some of your other concerns:

My concern
By: Byrain
2015-11-10 09:35:47 CST (-0500)

Was that while Rhytisma punctatum seems quite promising here, I’m not sure it has been recorded on this host before. At the very least I can not find anyone who has.

As for your reference, I don’t like how it says there are only two species ignoring R. americanum and some unknown species from the Canadian reference. These seem quite hard to research…

As for your obs 222386 I wonder if we would find a European species on North American maples, maybe it is that simple? Except some of the unknown Rhytisma from the Canadian reference including one on sugar maple also looks similar. I unfortunately don’t have much of anything concrete to add here.

It seems the species of maple doesn’t define the species of fungus, from what I read.
By: Andrew Khitsun (Andrew)
2015-11-09 23:36:19 CST (-0500)

As far as references go, there are some decent ones, but all wanting somewhat, in my humble opinion; here is one:

By: Byrain
2015-11-09 22:49:17 CST (-0500)

For future reference, these could be interesting things to save. Although I’m not sure what to do with them… That pdf was not as helpful as I hoped…

Host is Sugar maple Acer saccharum
By: Andrew Khitsun (Andrew)
2015-11-09 22:09:53 CST (-0500)
By: Byrain
2015-11-09 21:59:06 CST (-0500)

Mind sharing what species of Acer this is? I unfortunately don’t know Wisconsin trees…

This reference if you have not seen it already could prove useful.


Created: 2015-11-09 19:28:00 CST (-0500)
Last modified: 2015-11-12 01:01:16 CST (-0500)
Viewed: 67 times, last viewed: 2016-10-25 17:22:06 CDT (-0400)
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