Let us know how it works. This has been a tough year.

Thank you for sharing your spray recipe. I don't shy away from organically spraying and, as it were, I also use neem oil but combine it in equal measures with baking soda. I think research shows much better results with potassium bicarbonate that you use. For some inexplicable reason I never came around to buy it. I should do it next time. DynaGro is 100% neem oil and it's also my choice, as is Dr. Bronner.

I do wonder though about the concentration. For 1 gallon water, I use 1 Tb DynaGro neem oil, 1 Tb baking soda, and about 1 tsp Dr. Bronner as an emulsifier. I can't recall exactly why I use these measures because it was long ago when I started with this spray. It was probably based on one of Cornell recipes. Your measures are three times stronger and I'm curious about the reasons for it. I may as well do it too if my concentration turns out to be too mild.

Buford -- yes, it was quite a rocky Spring.

Jeri -- I used neem oil a few times back when I first got the roses as bands in 2013 and 2014 to clear up some mildew that they brought with them. I found no harm, so long as temperatures were not approaching 90F. Next time I spray, if it's hotter, I'm skipping the neem but keeping the potassium bicarbonate and Castile soap. And anyway, it's going to rain on Friday, so anything not absorbed will be washed off before it gets hot again.

Vesfl -- The recipes I found for the Castile soap and neem oil varied quite a bit. When I searched "potassium bicarbonate for roses" I stumbled upon this:

https://dengarden.com/gardening/Organic-Methods-of-Exterminating-Powdery-Mildew

Admittedly, it's a blog post. But I figured that if the recipes harmed her plants, she wouldn't be sharing them. For the potassium bicarbonate recipe, 3 tbs each of it and "horticultural oil" per gallon of water were mentioned. For the neem oil recipe, again it was 3 tbs per gallon of water. So I morphed them, and added the Castile soap.

:-)

~Christopher

You can also buy a powder called Remedy, potassium bicarb and a spreader-sticker to mix with water. Back when I used to spray, I sometimes used it. I don't remember ever having any burning from it. I did get burn from copper soap (growing season application) or from sulfur (ditto).

I was looking at the premixed brands which are based on potassium bicarbonate, but I found this to be cheaper. I don't plan on using the neem oil all year. Copper and sulfur I'd prefer to reserve for before the roses leaf out. I'm thinking that if I give them a "dormant blast" with those, I'll start with more of a clean slate. I know the spores travel on the wind, but I figure there will be fewer "traveling locally" if I clean out my yard first.

Some sources indicated that simply "washing" the foliage down with Castile soap once or twice a week will get rid of a lot of spores before they germinate, and leave a slightly alkaline residue behind. I've been dreading having to do this, but once I got it done, I realized it wasn't difficult, and was finished rather quickly. I don't think I can bring myself to using actual systemics -- I can't help but think that they'll kill off the beneficial fungi hooking up with the roots.

:-)

~Christopher

I don't spray either, but my roses had more blackspot than I have ever seen. Even generally-clean roses like Lamarque and some of the Gallicas were affected, and a China hybrid that may be Fulgens turned black all over. There are several reasons I don't spray, one of which is that I think strong roses can fend for themselves. The China hybrid looks fine now with new canes and clean new leaves.

Lindsey

The things you used are of course fairly benign ... barring burning, which may have to do with my conditions. (Anything over about 75 deg. burned foliage HERE.)

As to less-benign sprays -- we sprayed religiously for years. We sprayed right up to where our dog-of-the-time began to seizure violently whenever we sprayed. THAT was the end of it, for us.

And, anyhow, when there were fewer and fewer rose shows, and you had to drive further and further to find one, perfection just became less important to us.

lplantagenet -- Yes, this year some roses were looking rather rougher than usual, hence my decision to intervene somewhat. Again, part of that was that I didn't get to do post-flush pruning last year, and things were growing everywhere. Now that I've cut back quite a few roses, they can sort of "reset" and grow anew. Before I hit them with the spray yesterday, new growth was already getting dusty, and I didn't want that carrying through any further.

jerijen -- I hear you about toxic side-effects from some other fungicides, and that's why I won't use them. Normally, I don't mind some roses going naked after the first flush, because what I've come to observe is that their first set of leaves don't seem "built" to handle Summer conditions here -- they seem more "built" to handle the cooler temperatures of leaf-out time in April. But this year, bad foliage was coinciding with the first flush, at which point I felt it was too late to do anything, since anything sprayed would get all over the blooms. I felt the need to do something, since powdery mildew had run rather rampant. It wasn't about "perfection" so much as it was about keeping things in check -- a little bit here and there I can tolerate, but not great swaths of it. So far today, I don't see burned foliage, but I do see a sharp reduction in the white dusting. I'm guessing that at the moment, it's simply smothered rather than actually killed. We'll see how things look after the sporadic rain forecast for the next few days.

:-)

~Christopher

Re: neem oil and beneficial insects. I know that there is the debate about it, but I use this organic mixture for prevention mostly, a couple of times in early spring, and it shouldn't affect beneficial insects that feed on pollen and nectar because the flowers are not yet in bloom. Since the neem oil coats the foliage and stems, I find it very effective against aphids and other insects that chew leaves by making the rose leaves less palatable and keep them at bay. No black spots, no powdery mildew, no aphids, ... Unfortunately, I missed to do it this year. Lo' and behold, some of my roses and shrubs were literally invaded by aphids.

Sometimes, if it's excessively rainy, I do have to repeat it once or twice in summer to prevent mildew and blackspots. I will be mindful not to do it when the temps are higher than 75F as I'm now learning from jerijen’s comment about burning.

I hope you will update us on your roses. It's inevitably trial and error when attempting to walk the fine line between protecting our roses and other plants from pests & fungal disease while doing our best not to harm pollinators.

I just released 1500 ladybugs after discovering aphids. I'll give them a while but then may need neem oil. The kids begged for the beetles so I thought we'd try this first but I'm skeptical...

Interesting, Christopher. Not a smidge of mildew here. None.

Here, the mildew began with a few Gallicas, Damasks, Chinas, and Teas. As it spread on those individual plants, it then began appearing lightly on several others. As of right now, virtually all of the mildew appears smothered, i.e. very little "white dusting" remaining. But wherever it was I can still tell, since leaf shape was affected. I can't find any foliage burning, and in any case, it's about to start raining here any minute.

:-)

~Christopher

That really doesn't sound like powdery mildew. PM usually starts on polyanthas and ramblers. It is also usually a problem when conditions have been dry. The only time I've noticed it on a European OGR type is when we were trying to show R. macrantha. There was a very, very faint dusting that wasn't visible in the garden, but did show up under fluorescent lights. I've never had it bad enough to distort foliage or stop buds from opening.

Well, I don't know what else to call a white dusting like powdered sugar that begins on my Gallicas and Damasks. I'm in a warmer zone than you are, and this Spring we had an early warm-up with cold nights. There were stretches in April and May when daytime highs and nighttime lows differed by 30F. I've heard from other NJ gardeners with OGRs that powdery mildew hit them as well. Perhaps where you are the daytime temperatures didn't climb high enough early on in Spring, so you didn't get any.

I found some pics in my Spring 2017 thread showing what I've been calling "powdery mildew". Admittedly, I didn't take the pics to highlight the "powdery mildew", so it's not very "front-and-center". You'll want to click the pics to enlarge them. If you recognize it as something different, please let me know.

This is the rose called "Brite Bella Donna" by Dennis Favello, aka Belmont on here.

This is 'Botzaris'.

:-)

~Christopher