Monday, September 20, 2010

Disease resistance survey

Since 2007 I have pretty much quit applying fungicide sprays to my collection to prevent disease.* I have gathered data about the results with emphasis on identifying cultivars that prospered with little or no Blackspot infection. (I regard Blackspot as the single most destructive of the three major fungal diseases, as it has the ability to significantly weaken the plant, rendering it much more susceptible to freeze damage during Winter dormancy.)

I recognize, and wish to emphasize, that any list of highly disease resistant varieties compiled by one person in a specific region may be meaningful only to that particular site and/or geographic region. A cultivar that performed outstandingly in my garden may be a disaster in the South or the East, and vice versa. Keeping that in mind, the first group is a list of roses that I designate "Little or no infection". This group includes anything that kept at least 90% of its foliage even if it did suffer some Blackspot infection. Some cultivars had an infection rate of zero and these are marked with a +

William Baffin+
Lady Hillingdon
Indian Love Call
Duchesse de Rohan
Cecile Brunner+
Marie Pavie
Clothilde Soupert
Pinkie, Cl.
Crested Damask
My Stars+
Basye's Blueberry+
Rosy Purple+
The Yeoman
Red Radiance
Blush Noisette+
Maria Leonidas+
James Mason+
Marie vanHoutte
Lilian Austin
The Green Rose (R. chinensis viridiflora)
Soupert et Notting
Tiffany+ (now there's a surprise!)
New Dawn
Mme. de LaRoche-Lambert
Konigin von Danemark
Great Maiden's Blush (some years it gets some infection and as such, would be placed in the second category.)
Tour de Malakof+
Ville de Bruxelles
William III+
Ellen Tofflemire+
Souvenir de Claudius Denoyel
Darlow's Enigma+
Wedding Cake (some years it fits in category 2 rather than here)
Pompon de Bourgogne+
William Shakespeare 2000 (NOT the original William Shakespeare, which has very poor disease resistance)
Capitaine John Ingram+
Mrs. B. R. Cant
Precious Dream+
Little Mermaid+
Golden Wings (some years it fits in category 2 rather than here)
Star Magic+
Alberic Barbier+
Vineyard Song (some years this gets a + for complete immunity to Blackspot, 2010 included)
Basye's Purple
Dorothy Perkins+ (although, as most are aware, it Mildews quite readily from Mid-Summer on)
Errinerung an Brod (some years it fits in category 2 rather than here)
Blanc de Vibert (a very poor plant in most other ways, however)
Buff Beauty
American Pillar+
Joyce Barden
Mary Rose
R. centifolia cristata
Belle Amour+
Hebe's Lip+
Mutabilis (some years it fits in category 2 rather than here)
Yellow Lady Banks (although none of the Banksieas are reliably Winter hardy here and have been removed from the collection)
R. soulieana

Plus all of the Gallicas, with the exception of those that show conspicuous China or Hybrid Perpetual influence: these get some disease, often Mildew as well.

I include all of the North American species I grow as well. My R. clinophylla, two plants seed grown, from India, both suffer some Blackspot infection, although minimal.

List 2: Varieties that kept at least 75% of their foliage in spite of infection, and which outgrew disease quickly, with little impact on overall plant health.

Jeri Jennings
Distant Drums
Barbara Oliva
Incantation (some years it fits in category 1 rather than here)
Jayne Austin
Robert Leopold
Dick Koster
Reine des Violettes
Alice Hamilton
Rose de Rescht
R. damascena bifera
Charles Lawson
Souvenir de la Malmaison (although often plagued by terrible Mildew)
Sally Holmes
Mrs. William Paul
Constance Spry
Mme. Caroline Testout (some years it belongs in the 90% clean category)
Chianti (some years it doesn't belong in either group, as it does occasionally defoliate almost completely)
Variegata di Bologna (sometimes it doesn't fare well enough to be on this list)
Marechal Niel
Yolande de Aragon (some years yes, some years no)
Portland from Glendora
Sharifa Asma
Ghislaine de Felighonde
"Champagne Arches"
Marchionesse of Londonderry
Pie IX
Closer to Heaven
Belle Poitvine (and all of the "purebred" Rugosas)
Out of Yesteryear
Fakir's Delight
Linda Campbell
Sutter's Gold (some years not so good)
Golden Ophelia
Dragon's Blood
Violet Hood
Reveil Dijonnais
European Touch
Cuthbert Grant (This season it is one of the 90% and up varieties)
Carlin's Rhythm
Soeur Therese
Hot Cocoa
Fa's Marbled Moss
Savoy Hotel
Marchesa Bocella
Mme. Alfred Carriere
Paul Ricault

The third list I have compiled is one assessing the many Miniatures I have in my archive, the vast majority of which are Ralph Moore hybrids. The following group indicates those which maintained at least 85% of their foliage at all times, whether infected with Blackspot or not. Some cultivars were totally immune to Blackspot in my garden and are marked with a +

Sweet Fairy +
Golden Century (near 100% immunity some years)
Blue Mist +
Hall of Flowers
Nurse Donna
Ora Kelly
Red Cascade
Red Wand, climber +
Tom Thumb
Magic Carousel
Cinderella (near 100% clean)
Magic Dragon
Apricot Twist + (reliably immune to all disease in all years tested)
Cal Poly +
My Valentine
Rose Gilardi (near 100% immunity some seasons)
Glowing Amber
Magic Wand +
Sweet Chariot
Popcorn +
Little Meagan
Sequoia Gold
Red Alert
Red Germain
Little Buckaroo
Stacey Sue
Star Dust
Splish Splash
Unconditional Love (near 100% clean some years)

I'm sure I have missed a few plants in compiling this list, which is easy to do when surveying a collection of over 2500 varieties. I'll remind readers that this list in no way in meant to indicate that all of these roses will perform similarly in all climates and in all sites/soil conditions. I know for a fact that some of the historic (OGR) varieties I list as highly disease free fare quite poorly in other regions. Still, it should at least provide some insight as to general health of the varieties listed.

*One exception to this is the Ralph Moore collection, which is one of only two or three complete collections of commercially released Moore roses to be seen anywhere. As the curator of such a collection I feel the need to continue spraying these to keep them in good health, as I have only one specimen each of the majority of these.


  1. Hi Paul
    Great information.
    Have you grown Baby Love (SCRivluv), and if so can you comment on its fungal resistance in your climate?

  2. George,
    I don't grow Baby Love, no. I've looked at the work other people have done with it and decided it didn't appeal to me, so I've chosen not to include it in my collection.

  3. Great information. I love comparing this information from different sources to get a overall view of what a cultivator will do.

  4. The comment on Tiffany intrigued me so I had to do some checking. Checked out the broken done parentage to the grandparents could not find any reason it should be healthier than anything else except for maybe that it was bred by Lindquist and he certainly changed the way people bred roses. He influenced more than one great hybridizer. However when I checked my notes it seems that Tiffany does seem to be one of the healthier Hybrid Teas when it was included in no spray trials. It usually came out of these trials with around 75% of its foliage in tack which is an oddity for the class (Can not comment on the newer forms that has been released in the last 10 years or so because of lack of data). Which is nice because I short of have a soft spot for this rose even if it is a Hybrid Tea and I will probably have to make a space for it and Queen Elizabeth, Oklahoma when the day comes that I have room. Now skimming through the data collected the top rose in this class not taking too much time to really annualize the data to be absolutely sure that no rose beats it in the class but it seems the Hybrid tea with the highest marks overall is Pink Princess. The parentage of this rose gives it hidden powers away. In general however most hybrid teas, floribundas, and grandifloras in these studies fall between 50% defoliated and completely if it is a no spray garden. In the end I did not collect this data for the so called modern class. I have very little interest in these except for the miniatures which are hardly ever included (thanks by the way for that I find it a welcome addition) but I do like to compare parents I want to include to see if they are just disease resistant in one area or do they spread out their mythical powers over a wider area. I throw out any data on these trials if they are sprayed gardens, which up until recently most of the data came from sprayed gardens which still makes me scratch my head. But any way thanks for the data I for one will pour over it and compare it with what I already have.

    Oh by the way George on Baby Love from the data I have seen on it in most places it is a superstar, but in the few places the resistance breaks down it seems to break down spectacularly. I worry about breeding something with such resistance to it especially when everyone else seems to be breeding with it. But that is only my opion.

  5. Paul, these F1 wichurana hybrids, like the 'Alberic Barbier' listed here, fascinate me. I've just bought 'Albertine' and have cuttings of 'Paul Noel' coming on too as well as a few others I want to try. Have you ever used 'Alberic Barbier' in breeding? I'm also trying to find records of 'Albertine' used as a breeder. HMF lists only one descendant for each...

  6. > I recognize, and wish to emphasize, that any list of highly disease resistant varieties compiled by one person in a specific region may be meaningful only to that particular site and/or geographic region

    You can bet it. I can say at least that William Shakespeare 2000 can get a lot of blackspot when cultured in a stressing environment, (i.e in a pot). But I like it a lot anyway.