The best method is to spray with Bayer Advanced disease control for roses. It's a concentrate you mix with water and spray on the foliage. The other fungicides on the shelf will not get rid of existing black spot, they will just prevent it from starting.

Since you already have bs, I recommend the Bayer. Start off by spraying every other week, then you can go to every 3 weeks. It's a systematic that is absorbed by the leaves, so you don't have to spray under the leaves. However, it's a good idea to spray the ground around the rose, since that is where the fungus harbors and also any leaves that have bs will probably drop on the ground.

Save your self the trouble and toxicity and buy black spot resistant roses. Knockout roses comes in red or pink and they don't require spraying of any kind. Battling black spot with chemicals is an endless chore. Not to mention, I think that the chemicals in Bayer Advanced have been implicated in the honeybee disappearance. I would rather pick roses that don't need spraying and know I am not contributing to a potential problem. If you don't like Knockout roses I think the Birmingham Botanical Garden has a great list of trialed roses, many of which are black spot resistant. Many varieties of "antique roses" are bs resistant. I have a beautiful climber called "Climbing Pinkie" that requires no spraying. Also, if your roses already have the fungus it will do no good to spray now. The spray or granules only work as a preventative measure.

Danth,
I forgot to mention several cultural practices that will help keep bs at bay. First, the affected leaves will drop off the plant, so you want to be sure and throw them away. Second, water from the bottom of the plant; this will keep the leaves dry. Use a drip system or similar irrigation. If you would like an organic method for controlling bs mix 1/2 water and 1/2 milk and spray every week. This keeps the pH of the leaf surface at a place not hospitable for bs. I have heard skim milk is best, but I am a lazy gardener and prefer not to do all that work :)
Good luck!

cherzon, he already has blackspot. And I've tried everyone of those 'cultural practices' and they don't really help.

The Bayer fungicide is NOT an insecticide and has no relation to the imminaclorid which has been one of many thing suspected of affecting bees, but there is no proof.

Also, as I stated the Bayer disease control DOES get rid of existing blackspot, so you are incorrect about that as well.

Please think carefully before you post mis-information like that.

In our area, the weather conditions allow blackspot to get out of control in a hurry. The Bayer Advanced products work very well and are available at lots of stores. Some of the formulations and bottles look very similar, so read the labels carefully to make sure you are getting the right one.

I've use Mancozeb (Manzate), which does kill existing Blackspot on contact, for years, along with Bannermax, which prevents Blackspot. That said, I grow hybrid teas, which are notorious for the disease, and need serious control. I've been impressed with what Bayer has brought to the market in the last couple of years and would be tempted to try their Advanced Disease Control. It's got a fungicide called Tebuconazole as its active ingredient and reading up on that shows that it's been used for a long time in agricultural applications as a fungicide. Go for it and let us know how well it works.
Bill

Bill, it (Bayer Disease Control) is fantastic. I have over 70 rose bushes, many HTs and Austins which are BS magnets. This product keeps them clean.

I found out how bad bs could be last fall. I stopped spraying in Early October, but it stayed warm and most of my roses came down with really bad BS. Some never got any, but most had at least some. The weather was so weird, some of them carried the BS over to the spring. But as soon as I stared spraying, it's gone.

I wouldn't have this many roses if it were not for this product.

Great info, everyone! Thanks

I was searching for info on black spot and came across this thread. Does anyone have anything else to add?

butterfly, not really. Except that because of our weather patterns this spring, I had black spot as soon as my roses leafed out. This was with doing a lime sulphur dormant spray and a mid-December spray of Bayer. So the pressure is strong.

I have sprayed twice already and it seems to have halted. We just have to hope it gets warmer and stays warmer so the BS will go away! It thrives in damp 60 degrees-ish type weather.

Buford, could you tell me more about the lime sulphur dormant spray? Is there a reason to use it at that time rather than the Bayer year round? Thanks!

Butterfly, in order to kill the blackspot spores (among other things) the lime sulphur has to be at a concentration that would damage live foliage. That's why it's called a dormant spray concentration. In fact, many rose growers use it to get rid of all the old leaves in the winter so they don't have to pull them off when pruning.

You can use it at a lesser concentration during the year, but the other fungicides are more effective then and less damaging to the foliage, plus they don't smell as bad.

I have gained great knowledge from this thread. Thanks to all! I have black spot on a rose bush but I am not sure of the type of rose bush. I just noticed on yesterday that the black spot covers over half of the bush. It is still green and bushy but the buds are not opening and if they attempted to, they kind of wilted and died. My questions are: with so much of the bush covered with black spot, is it still treatable or should I get rid of it? Also, the builder of the house planted these rose bushes and probably assumed that this particular bush was a knock out rose bush. I have several knock out rose bushes in the yard and they are doing great. This diseased bush is fairly close to my wonderful knock outs. Will the black spot get to my knock outs? Help pleeease...

I was glad to find this. If what I am trying doesn't work, I will get Bayer Advanced. I seen it last time I was at a garden center, but didn't know it worked so well. Thanks to all for the tip!

For now, though, i'm trying a solution I read about online. Everywhere I read about it, people said it worked so well... So... I'm hoping. It's 1 gallon water, 2 tablespoon Baking Soda, 2 tablespoon Dawn dish liquid. It's supposed to be a Fungicide/Insecticide.

Fingers Crossed!

I personally don't like using chemicals, so I fertilize my roses regularly. I heard from a friends grandmother that keeping them well fed will keep black spot at bay and it's working great for me. I also make sure to water at the roots and not on the leaves. This does not get rid of it completely, but I'm happy to say I only see 1 or 2 affected leaves on each shrub now instead of a ton of them.

On a side note, I'm really tired of every post regarding black spot having someone's opinion about only buying black spot resistant roses!

1. These people that post already have black spot, so help them with advice they can really use!
2. I personally (and obviously others) would rather treat the black spot than not have so many beautiful roses!

I'm not trying to pick a fight or highjack this thread, but come on!

Diana

ollirose, I agree. I'm trying to be as organic as possible, but I don't see the sense in allowing all my roses to be defoliated with disease and using a spray solely for that disease only on my roses.

black spot seems to be very weather related. If it's hot and dry, you don't see much of it. Cooler and wetter, it's impossible to get rid of. That's why I prefer to prevent it with a systematic I spray every 3 weeks instead of waiting for it to strike.

I bought the 3 in one granules, mainly for the fungicide. It's systemic and I was told that it wouldn't burn my roses when it gets hot. After reading the label, I found that it cannot be used on container plants. Some of my roses are in pots with holes in the bottom (well- draining pots). Does anyone have any experience with this product in this situation? Guess I'm worrying about the fertilizer burning the plants...
TIA