Hi!
Some of the spinosissima types and a few others I know are resistant to powdery mildew, as faras I know.
But always be aware, it also depends on the idiotype you get.
The resistances are not in every idiotype of each of the species.
Here are some examples:
R. agrestis, R. glutinosa, R. helenae,
R. nutkana, R. omeiensis pteracantha, R. hugonis.
Greetings from Germany,
Arno
Roger,
Of the Buck roses that you have used, what ones have been a source of Powdery Mildew? I know Folksinger is fairly prone to produce PM ridden seedlings (at least for me). What other Buck roses have you used?
Anything from Sunsprite, Gingersnap or the Color Wonder line carries that chance. Of the warm colored Bucks, the ones with Alexander are prolly less of a chance than the above 3.
All: thanks for the responses!
Steven: Unfortunately, my mildew information is currently in the form of colored tags planted with the seedlings (1 for mildew, the 2nd for LOTS of mildew). I am working on my limited memory. However, I know that Folksinger (you must be psychic), Carefree Beauty, and Royal Edward (an explorer) were the most troubling parents. My concern abut the explorer rose Nicolas is due to the fact that it gets really bad mildew outside, but my seedlings from it are too young to show trouble yet. In fairness to these roses, this is otherwise greenhouse mildew, which seems to be much more severe. I can
I found Powdery Mildew on one of my very promising year old seedlings with Legacy as Grandparent this morning. THAT was disappointing!
Hi Roger,
take potted plants of them and set them at a drier and sunny south side, you will know after one summer, if there is a good genetical material within them. 
I did it this way.
Also one woodsii fendleri (Cinnamomea) was very good, so far.
Greetings,
Arno
I recently obtained ‘Carefree Beauty’ because of how well ‘Knockout’ does for me. The genetics behind Carefree Beauty are complex but I believe that it is the species Rosa Laxa that gives it BS resistance. Knockout seems to be more BS resistant than Carefree Beauty in my yard.
I have a R. fedtschenkoana seedling in a small pot that dried out a great many times last summer. There was never any PM. But maybe that was because the leaves dried out and died too fast for the PM to take hold!
Rob
Oh, Im sure the mauve buck roses would pass on PM seedlings, too. Its sorta hard to escape PM and mauve, especially with the earlier mauves. Even Neptune produces 90% mildew magnets, and it is from the 2000’s.
Environment really does seem to be the overriding factor when it comes to whether a rose is tolerant to disease or not. It is the genetic make-up of the pathogen population in that environment, prevailing weather conditions, and horticultural practices that in my opinion really drive this.
Horizontal resistant is tricky. Because it is quantitative, it is not as easily followed through pedigrees. Everest Double Fragrance is a great example of this, at least I have no idea where the disease tolerance is coming from.
There are 2 Buck roses that really should have been looked at that are not listed, Folksinger and Prairie Harvest. These are the 2 Buck roses that exhibit the best disease tolerance in my garden. They are both out of Carefree Beauty x Sunsprite. Earthsong, Music Maker, Aunt Honey, Prairie Sunrise all have disease issues in my garden. Alex MacKenzie, Baby Love, Home Run, William Baffin, John Cabot, and Simon Fraser are the ones that have never shown signs of disease at any time during the season. Morden Sunrise, Champlain, Folksinger, Prairie Harvest, and Everest Double Fragrance show signs late in the season. PALS Niagra, Roberta Bondar, Jim Lounsbery, Red Fairy, Distant Drums and Aprikola are too new for me to really judge.
Liz
Liz, I’ll second ‘Prairie Harvest’ and ‘Alexander MacKenzie’ as two of the toughest (most disease resistant and tolerant of neglect in general) roses here in Maryland too.
And another bit on the subject of spinosissima heritage and mildew resistance (for Arno and Roger)… I have a bunch of F1 seedlings of rugosa X spinosissima… some of these get almost covered with mildew every year… others only get a little bit. But aside from the ugliness of that mildew, they all are very strong and healthy plants. So, spinosissima heritage won’t always necessarily give mildew resistance.
Folksinger is very prone to PM for me. Its good with respect to BS but it would start puckering up with PM before just about anything else in my Nebraska garden.
In the last 2 weeks, I have been doing the computer entry of some data I have collected over the last 2 -3 years regarding recurrence in seedlings from various species crosses. The process has sharpened my appreciation of why it is so difficult to find published references to such numbers.
Having said all that, can anyone tell me what percentage of recurrent offspring I should expect from a cross of a modern rose (like a hybrid tea) with Applejack pollen? It has many second or later generation descendants, but only two first-generation descendants. I gather from this its hybrids tend to be non-recurrent (or recurrent only as large, mature shrubs). Can anyone offer even a rough idea?
It amazing how different cultivars resistance is lost over time and then other retain their resistance. Buck roses seem to be retaining this resistance longer than other.
I remeber some old gallicas and damask growing at my grandma’s place (In Nebraska) by the garage. They had blackspot like everything else but they lived through it. Everythng else died in a few years no matter what chemical they sprayed and they where not afraid to spay like we are today. For example I remeber my grandma telling me how horriable it was the outlawed DDT. But anyway maybe breeding plants capable of living through infection is another route.
Adam, Gallicas are such a mixed bag in terms of BS resistance. There are some that get BS as fast as any modern HT here and completely defoliate(Cardinal de Richelieu, Gloire de France are examples, but there are many more). There are some that get BS, but keep their cruddy leaves (Hyppolite, Belle de Crecy, Charles de Mills, Anais Segales and many others). But there are also gallicas that stay pristine year after year even here in MD. Examples of such are Alice Viena, Jenny Duval, Tuscany Superb (can get some crud, but not much), Belle Isis and some others. The only Damask that mostly stays clean here is Ispahan, others get BS and defoliate or get “brown crud” and keep their leave, but still look ugly in the second part os summer.
Olga
Noooo! Don’t say that. I’ve just got me a Cardinal de Richelieu and (knock on wood) so far it has great green foliage. If it’s prone that means I’ll get it…so it’s gonna defoliate this summer?
The Gallica and Gallica hybrids at Washington Park always mildew, which is a bad, bad sign for this area (low mildew area). Also, Chianti is a blackspot disaster lol. I have no clue why either. Then again, Austin didnt use the best of the modern reds to make it, either.
Here is picture I took of Polonaise last fall. It seams to be another disease resistant Buck with Prairie Princess as a parent. This was taken at the no spray/low maintenance shrub garden at the Minnesota Landscape Arboretum
