Interesting topic of concern to all rose growers. I look forward to those northern roses.

Interesting, because I have been told that there are 6 strains of blackspot that are prevalent in the US, very much location dependent.

Good thoughts everyone, Canina was the root stock in Canada that I could not think of the other day, I believed that testing was only done on own root roses. Under stock would be a problem. Surely this is another article they wrote on this. They did address the newly developing stains of bs.

Diane that part I was unsure of so I don't know why they picked those three strains. Glad you added that.

Dang, unlike the other KOs, Blushing Knock Out was susceptible to one race. I just planted a bunch of them in a public garden.

I ordered it also. Hope that strain isn't here.

Check your PM Patty for contact info...

Jim1961....I was at a NC District meeting a few years ago where David Zlesak or one of his undergrad students stated that there were possibly 12 to 13 races of BS, but race 12 & 13 weren't totally agreed upon in the scientific community as new races so 11 races seemed to be the agreed upon number with possibly 2 new ones.

Oh ok on the 11...I just emailed David Zlesak right before I read this wirosarian...

I no longer pay attention to disease resistance status because I have been both surprised and disappointed so often. There are too many variables. If I really adore a rose that fails in one spot, I'll again in another spot, sometimes getting the second try from a different vendor. More often than not, the second one does fine. I am also no spray, so whatever variety of blackspot I get, I just put up with it.

Besides the different strains of blackspot, you also have to keep in mind where you are, what your native soil is like, how much rain you get, how well you feed the soil, etc. In areas with long periods of "blackspot weather", the same rose will be under more pressure than it would be elsewhere, even if the strains are the same. A rose which is growing vigorously can often replace infected leaves quickly, so infection won't be as noticeable. The roots will affect how much water and nutrients the rose can absorb, so own-root versus each rootstock would have to be considered. Winter damage can also come into play, and possibly not in the direction you expect. By this I mean that roses with a lot of dieback will have less cane remaining which may be harboring blackspot spores. In reality, these tests would be best carried out in many regions to give a better idea, and not just because of different blackspot strains. Since waiting for that will take a while, another method would be to see what does well for others in your area and conditions, and go from there.

:-)

~Christopher

I agree with Christopher... But I've also seen 2 alike roses side by side one always had BS the other stayed clean...Why? Just to many other factors that can come into play besides strains...

Interesting thread Patty! Blushing KO is very health, no BS, PM issues here.

Blushing KO was healthy here also.

Exactly what Aqua Eyes and Jim say. I've had 3 Belinda's Dream roses. One grew in a large pot in full sun on its own roots and produced a ton of wonderful blooms for about three years and then slowly died. Another currently grows on Fortuniana in a not so great location and gets some BS, has grown very tall and produces much larger, albeit much less blooms yet it keeps on trucking. The third grew on its own roots in the ground and failed miserably. I have recently just purchased another one to grow in a pot again as that was the way it provided the most blooms. I'll be keeping my grafted one and wishing it was in a better location, but I wont risk moving it as Fortuniana doesn't like being moved. I'm betting it will also get better and better with age as it has thus far. So many variables, many different results. All the same plant.

Another Earthkind rose that I grow (right next to my BD) is Duchess De Brabant. Does she get BS? Yes. Does she get PM? Yes, but does she shake it off and bloom continually? YES!

Another one I grow is Knockout (is KO still considered and Earthkind?) I grow both pink and red double. Do they get BS? Perhaps not, but they get all sorts of other stuff that makes them unattractive certain times of the year. They do however bloom and keep growing. Currently both are ridiculously happy and on their 3rd year in pots and are producing some of the best flowers (for KO) I've seen so far.

I recently purchased SPICE rose as I've still been impressed with the designated Earthkind roses. I do not expect them to NEVER get BS, I do however expect them to brush it off and continue to grow and bloom. I only wish more varieties could be designated to the program. For example, my most disease resistant and best performing rose is Livin' Easy. It has out performed every single rose in my garden (over 150 varieties) and is not a designated EK, even thought it out performs all my other Earth Kind roses. Mine is grafted on Fortuniana and is spectacular in mid summer. Here she was last July. She's about 5 feet tall.