I acquired 10 OP seeds of Rainbow K.O. last Fall and after normal processing I had 5 seeds germinate which isn’t too bad. But one of those 5 was without chlorophyll and died. Two of the other four had a very bad case of powdery mildew.
Not a very good track record although is was a very small test sample. Only one of the seedlings had some intresting colors and narurally it was one of the powdery midlew seedlings. The other 3 had light pink color with smaller flowers than Rainbow K.O. I have used Rainbow K.O. extensively on several roses and it is a very good pollen parent and a poor seed parent so far. It does set hips on its own but I have not had any luck with cross pollination with other roses. It is completely disease free here in the humid Gulf Coast so far. It is far from a striking rose in the garden but I’m hoping it will take on a lot of the colors from the seed parent it is crossed with and that it will carry the continous blooming quality and disease resistance over to its seedlings.
Patrick, does the original ‘Knockout’ get powdery mildew in your climate? Or is ‘Rainbow Knockout’ better for you?
In our climate ‘Knockout’ gets too much mildew for me to use. I would not be able to keep many seedlings from it since I cull PM susceptible shrub type seedlings. ‘Home Run’ seedlings have been quite interesting and I think for powdery mildew resistance HR has been a better line for me to follow.
I have never seen powdery mildew on the original Knockout here. But like I said Rainbow Knockout has been completely disease free. I like rainbow knockout because it is always in flower and lots of them and also because it stays fairly small and can be used to downsize bigger roses and maybe give them disease resistance also. We don’t have rust here but the advertisements said rainbow knockout has excellent resistance to all three main diseases, Blackspot, powdery mildew and rust. I’m not 100 % sure its powdery mildew I had on those two rainbow K.O. seedlings as I have never seen powdery mildew indoors before. It certainly did not look like the mildew that I have seen outdoors. The seedlings were completly covered with a very fine white powdery substance and the plants looked fine.