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+
Mermaid+
Dortmund
Lady Hillingdon
Kathleen
Trier
Sidonie
Indian Love Call
Duchesse de Rohan
Cecile Brunner+
Marie Pavie
Salet
Clothilde Soupert
Pinkie, Cl.
Crested Damask
My Stars+
Basye's Blueberry+
News
Rosy Purple+
Westerland+
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!)
Penelope+
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+
Marianne
Ellen Tofflemire+
Nightmoss+
Souvenir de Claudius Denoyel
Marbree
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)
Renae+
Indigo+
Capitaine John Ingram+
Lamarque
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
Russeliana
Dorothy Perkins+ (although, as most are aware, it Mildews quite readily from Mid-Summer on)
Banshee+
Errinerung an Brod (some years it fits in category 2 rather than here)
Gallicandy+
Blanc de Vibert (a very poor plant in most other ways, however)
Armide+
Buff Beauty
Excelsa+
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)
Veilchenblau
Hettie
Yellow Lady Banks (although none of the Banksieas are reliably Winter hardy here and have been removed from the collection)
Montecito
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.

Roundelay
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)
Sombreuil
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)
Violette
Portland from Glendora
Oshun
Sharifa Asma
Ghislaine de Felighonde
"Champagne Arches"
Smoky
Marchionesse of Londonderry
Pie IX
Verschuren
Kazanlik
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
Tradescent
Dragon's Blood
Violet Hood
Reveil Dijonnais
European Touch
Cuthbert Grant (This season it is one of the 90% and up varieties)
Floradora
Carlin's Rhythm
Soeur Therese
Hot Cocoa
Serendipity
Pelison
Fa's Marbled Moss
Savoy Hotel
Marchesa Bocella
Botzaris
Awakening
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
Frostfire
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 +
Playgold
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
Pinstripe
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.

141-09-02: un-named diploid X 'Home Run'

141-09-02: un-named diploid Polyantha X 'Home Run'.

The rose used as a seed parent in this instance is a diploid Polyantha developed by David Zlesak and shared with me for breeding purposes. I don't have any record of its exact parentage, so I best not quote what I remember in case I'm wrong! The Zlesak Poly is a cluster flowering dwarf plant halfway between a Polyantha and a modern miniature in style, with clusters of 2" double, cupped crimson blooms bearing a pale, near-white reverse. To my nose, it offers a very respectable "fresh" scent. It is a very attractive little shrub and I hope David might consider it as a legitimate garden shrub of commercial value.

I used the "Z Poly" last year in conjunction with a number of other diploids with the goal of maintaining a strongly pigmented diploid line. I also included Carruth's 'Home Run' in the list of pollen parents, as it is a triploid and will presumably give both haploid and diploid pollen grains, and so this cross, 141-09, should include a mix of diploid and triploid offspring.

Many of the 141-09's were very good in terms of color, vigor and foliage. I selected about 15 seedlings for evaluation. Most are in shades of deep red or crimson, and most are singles or nearly single. All appear to be cluster blooming and many seem to have inherited much of the growth habit of 'Home Run', which I'm not altogether pleased with. (I find 'Home Run' to be a rather homely shrub as regards its architecture)

Next year the best of the 141-09's will go outside into the open garden to establish for disease resistance evaluation. This is a high priority matter with this group of seedlings, as I am determined to develop my own line of shrubs that carries near 100% immunity to "the big three" fungal diseases. We can hope, anyway.....

56-06-05: a new yellow climber.

I've mentioned the Moore Wichurana breeder 0-47-19 several times before, and I thought I should show some of the work thats coming out of it. I use it with the goal of improving disease resistance, plus it often brings added vigor to a breeding line, and the seedlings are generally very easily rooted from cuttings.

Illustrated here is 56-06-05, a cross of 'Joycie' X (0-47-19 X 'The Yeoman')*. The pollen parent, listed as 42-03-01, is a vigorous, once-blooming climber with glossy, disease free foliage and clusters of butter yellow blooms at most every leaf axil along the arching canes. 42-03-01 rarely sets seed and its pollen is only marginally fertile, but I have persisted in getting seedlings from it since it is an opportunity for improvement of the health and vigor of the breeding line. 56-06-05, the yellow seedling pictured here, is the first seedling from 42-03-01 worth mentioning so far, and I hope it passes on its health and vigor to another generation.

56-06-05 is also a vigorous climbing plant, with bright grass green glossy foliage that so far has had no problems with disease. Blooms are fully double and about 2.5 inches across, with a pleasant, but mild Tea (phenolic) scent that often accompanies yellows. It took two years for this seedling to mature enough to start flowering, which is a reminder that sometimes its worth keeping an interesting seedling, even though it may not bloom the first (or second!) year. I'm much more inclined to keep un-bloomed seedlings from unconventional breeding lines in the hopes that they may have traits of value in furthering the line. 56-06-05 appears to be fertile, as it has produced seed hips with several pollens. I won't be able to comment on fertility till next Spring when I find out if these seeds germinate or not.

Note to breeders: I have a couple plants of 42-03-01, the pollen parent of the seedling above, if anyone is interested in working with this seedling.

* 42-03-01 is listed as 0-47-19 X 'The Yeoman', although I have reason to doubt the parentage. I suspect this seedling may in fact be a 0-47-19 X 'Out of Yesteryear' seedling that got mislabeled, since it bears a strong resemblance to several seedlings from the latter cross. It is also suspicious that a cross using 'The Yeoman' would produce anything in yellow, whereas 'Out of Yesteryear' easily could.