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'Martine Guillot ®' rose Reviews & Comments
Discussion id : 124-937
most recent 11 JAN HIDE POSTS
 
Initial post 11 JAN by Ericchn
The website of Guillot Rose declares that Martine Guillot has excellent resistance to blackspots :

“Et pour parfaire toutes ses qualités, la rose Générosa® Martine Guillot® offre un parfum intense et un feuillage vert parfaitement résistant aux maladies. C’est un modèle de résistance à la principale maladie du rosier, la Tâche Noire ou Marsonia dans les instituts de recherche. ”

So why in the description page it is marked “susceptible to blackspot”?
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Discussion id : 95-221
most recent 4 OCT 16 HIDE POSTS
 
Initial post 4 OCT 16 by Give me caffeine
Available from Swiss Garden nursery in Perth: http://www.swissrosegarden.com/r651/martine-guillot-roses-perth
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Discussion id : 95-220
most recent 4 OCT 16 HIDE POSTS
 
Initial post 4 OCT 16 by Give me caffeine
Available from Ladybird roses: http://ladybirdroses.com.au/martine-guillot
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Discussion id : 95-218
most recent 4 OCT 16 HIDE POSTS
 
Initial post 4 OCT 16 by Give me caffeine
The description page for this rose says it is susceptible to blackspot. There is nothing about that in the references, and the only member comment that mentions blackspot indicates that this rose has good resistance.

The member ratings (which admittedly must frequently be taken with a pinch of salt) claim excellent resistance to disease, but obviously without any indication of which disease this relates to.

There is one photo (Photo Id: 288945) which appears to show some "blackspot", but based on a recent conversation with Michael Garhart (https://www.helpmefind.com/gardening/l.php?l=21.288890&tab=32) it looks to me as though that spotting may be caused by Cercospora instead. The grey centres in the spots are a trait of Cercospora, and don't appear with Diplocarpon.

So the question here is: where did the "Susceptible to blackspot" warning come from?

Edit: Found this over on houzz (in the "Guillot Generosa Roses" thread) - "I used to live in Thailand (20 years ago) and now I live in southern Mississippi. We have very high heat and humidity here too. I have 5 plants of Martine Guillot and they are some of my healthiest roses. They do not have problems with blackspot or mildew and I rarely spray."
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