I have my seedlings hit by mildew, Is anyone aware of the the old treatment of water, baking soda, veg. oil and a drop of oil. It worked for me well on the canadian roses that are not disease resitant. I would like the receipe/ratios to this solutions since I misplaced it.
thanks
Johannes
The mixture I use is 1tablespoon baking soda, 1/2 tablespoon horticultural oil, to one gallon of water.
The original recipe called for 2 tablespoon of oil this was not especially good on the seedlings so you may have to experiment with the amount of oil. I do not spray established roses. Only seedlings when they are in the house. But the worst ones get thrown out before they can even make it outside.
Hi Johannes,
I know this is not what you are asking, but try ‘Baby Love’ in some of your crosses. Although it is recommended for black spot, it does a fantastic job of cleaning up the seedlings of powdery mildew, although I am not sure that it would contribute to cold hardiness…
Jim Sproul
Sorry Jim but this is a no go for for my cool weather and also I like better working with diploids
I am always in interested in the ideas that are given to me Keep the comming!
For some reason diploids in general, including species, seem more to Powdery mildew. I’m always trying to breed away from it.
Culling the worst early saves a lot of time.
Curious, curious how our experience is different about PM.
I do a lot of species and also diploid breeding never cull a seedling and PM do not bother me at all…
“never cull a seedling and PM do not bother me at all…”
I’m guessing the difference is environmental. I do not experience Blackspot here, at all.
I can test for Powdery Mildew and yet I know some climates are worse than mine for infection.
For instance ‘Knock Out’ is awful here in Southern CA. The first time I saw it at the Huntington Botanical gardens it was covered in mildew.
Location, location, location…
I primarily work with evergreen diploid Asian species derivatives.
Banksia, gigantea, laevigata all mildew here to some extent.
I have seen Laevigata mildew appallingly here.
Fortuniana is an example of a near species that can mildew here.
Even Flower Carpet will mildew in my non-mildew prone area of Oregon. If a surge of new growth hits at just the right time, its a recipe for mildew. So, even wichurana types can be prone. Promoting excessive growth with nitrogen is usually asking for it though.
Maybe some of Moore’s earlier diploid types close to wichurana would be helpful regarding mildew and breeding options for some of ya all. I have been growing out Sweet Sue, which is one of those types, and have been very pleased with its level of repeat and nice foliage. Each leaflet is like a little tiny waxy shield, lol. The photos of it on HMF are not representative of this rose at all. I am unsure of its hardiness but it could always be brought indoors during the winter if only being used for breeding. Anyways… the point is that there are always options out there if you squint enough 