fungus Sphaceloma rosarum

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fungus Sphaceloma rosarum

Postby dgermeys » Wed Oct 04, 2017 5:35 pm

Does anyone know roses that are resistent to the fungus "Sphaceloma rosarum"? This result of this fungus are small holes in the leaves. One of my seedlings seems to suffer from this rose disease. The funny thing is that she seems not to suffer from blackspot very much though.

So I was wondering if anyone knows some roses (garden or species) that are resistent to the "Sphaceloma rosarum" fungus.

Thx!
Dane from Belgium
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Re: fungus Sphaceloma rosarum

Postby bvan der hoek » Mon Oct 09, 2017 10:32 pm

Hi, Dane! I had to look up Sphaceloma rosarum and found out it is our old enemy Anthracnose. This disease and Cercospora are sometimes lumped together and called "leaf spot". It seems to be very common in a lot of the newer blackspot-resistant hybrids. At least that is the case in my garden! Several RHA members are working to breed resistant varieties. I hope they will post on this thread. In the meantime, you could do a search of the forum using the word "anthracnose" and see what you find.

Yours,
Betsy
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Re: fungus Sphaceloma rosarum

Postby Larry Davis » Thu Oct 12, 2017 8:29 pm

I wrote an article on the history of this disease for the RHA newsletter a few years ago with some nice illustrations out of old sources. It has been around and recognized for around 100 years in NY state at least. Superficially looks kind of like BS but doesn't stimulate leaf drop as readily on most plants. But by end of summer they may be nearly defoliated. In the interim they look tacky. I have rather a lot of it on R wichuriana hybrid New Dawn, and its offspring. Don't recall it on Dr. van Fleet the non-repeating parent of the sport New Dawn. I'll need to look more carefully.
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Re: fungus Sphaceloma rosarum

Postby dgermeys » Sat Oct 21, 2017 6:14 pm

Thank you Betsy,
Thank you Larry. I will try to find your article in the RHA archives. Do you remember what year you wrote it?

I hope to come across some roses that are resistant to this disease.
Dane from Belgium
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