Serenade advertises it is not phytotoxic, meaning it shouldn't burn. Most garden chemicals warn against spraying when temperatures hit the eighties precisely because of foliage burn. Stay away from anything with an oil in it as oil will positively burn in those temperatures, even if sprayed weeks before. Rinsing off the foliage will make no difference.

Your alternative for chemical protection is Bayer Rose and Flower systemic. You dilute it and pour it into the soil. Be careful with it and follow the instructions to the letter or you can burn the plants with it, too.

If you bought Knock Out, you DID buy one of the more resistant roses. Recent research has shown there are three genetically different strains of black spot in the US. Unfortunately, not every resistant rose is resistant to all three types. Perhaps your Knock Outs aren't resistant to the strain infecting your area? Kim

I live in Metro Atlanta, it gets very hot here. I spray all spring and summer with Bayer Advanced Disease Control. I spray in the morning when the roses are still covered in a bit a of dew and the spray dries before the sun gets high. I've never had a burning problem.

Just an FYI, the Bayer Drench has a strong insecticide in and it isn't as effective for black spot as spraying is.

I ditto what buford says. We get very hot here too and have never had a burned leaf from the Bayer Advanced Disease Control and I too spray in the morning when theres a bit of dew.

Thanks for the help guys, But one question, do you only use the Bayer spray? I heard that your should alternate between two fungicides to fight resistance. If not, then great, because the alternating can get expensive.

I also want to know, will the Bayer affect the size of my rose blooms? I tried non-organic treatments before, and my roses got smaller. Thanks a lot guys! You are so helpful!

I don't use another fungicide. I think the idea that you need to use two different ones was for the older type fungicides like Daconil. Bayer seems to work fine. I also think that the small bloom was a result of the Bayer drench fertilizer, not the fungicide. I haven't noticed the blooms being smaller.

The Bayer fungicide is said to have both systemic and surface actions, so no alternating is needed.

Smaller blooms usually occur in hotter weather. I haven't found that fungicides have led to smaller blooms.

Also, fungicide application should be started soon after pruning, it is a preventive treatment. Do not wait until you see blackspot, it is more difficult to erradicate.

Bayer should still be alternated with another type of fungicide. Systemic or contact makes no difference. Fungi can still build up resistance to it. It just takes a little longer with Tebuconazole.

Thanks for the help everyone! I will use the Bayer spray, and alternate between the Serenade just to be on the safe side.

Learn to tolerate some blackspot :)

You might know this already, but go to Lowe's Home Improvement to find Bayer Advanced Disease Control. Most places just carry the All-in-one formulation with insecticide and fertilizer. Not only is the Disease Control safer, it will last much much longer for the same amount of money. Incidentally, I use Bayer about 3/4 of the time, occasionally alternating with Banner Max. Ortho Triforine products seem ok too.
Since no one has mentioned, I'll just put a plug in for thick mulching in summer and thorough watering several hours before you spray. Hydrate those plants. Someone already said it, but I'll second it that oil-based formulas are awful for hot weather. I tried some neem oil from Greenlight once and badly chemical-burned my roses.
Mike

This is a different approach to the subject, but have you considered trying to grow roses that don't need much chemical intervention? I would think that the tea roses (as opposed to the hybrid teas) and China roses that do well in hot, humid climates might be an option for you. The long-term consequences of the frequent use of toxins are not well-understood, but may affect your children and grandchildren. I garden in a hot but dry environment, and have had to discard quite a few roses that don't do well here, but now have an assortment, many of them tea roses, that do beautifully with an organic regimen. Since I moved here about five years ago I've seen a great increase in lizards, birds, bees and other wildlife which benefit from a chemical-free environment. I don't mean to offend, but many people aren't aware that there's a great assortment of the older roses that are tough, carefree and beautiful and can be grown without chemicals that are harmful to everything in the environment.

Ingrid

Here's an update...well, we have been getting so much rain here. It has also been very humid. I tried the Bayer Advanced and Serenade every 7 days, but I still got the blackspot. My Knockout roses are now just canes. Maybe I should cut them down this fall, or move them to the backyard where I can give them more tlc. These are the only roses that got the black spot. My tea roses are doing great. Out of my 14 roses, I can't believe that only my Knockouts look that bad! Oh well. You can't win them all.

I'm so happy to see Mike-in-New-Orleans post, I hate to contradict, but here goes ... Banner Maxx and Bayer Disease Control are both -azoles, so it may not count as a rotation.

Follow the pros - talk to Robbie Tucker at Rosemania if you have any doubt, but he recommends Banner Maxx with Manzate every other spray - that's spray with Banner Maxx alone, wait two weeks and spray with Banner Maxx and Manzate. Wait another two weeks and spray with Banner Maxx, then two weeks later and spray with Banner Maxx and Manzate ... then repeat.

Since Bayer Disease Control is essentially the same family of chemical, you can do the same thing. Bayer actually has an advantage in this regard as long as you don't have high numbers of roses (Banner Maxx has the advantage in volume pricing), in that it contains all the spreader-sticker stuff mixed in. I've done it this way and it works. Simply do the same as above - mix in the Manzate (Pentathalon) every other spray.

If you really have the money, rotating with Compass is best. I have tried Funginex (Ortho Disease Control), but it's only good for 1 week. I've also tried Heritage, thinking its strobulin mixture was similar to Compass. Unfortunately, it's not similar enough apparently, because results are only good for 1 week.

At any rate, your solution is simple and easily cured. Either choose Banner Maxx with a spreader-sticker, or buy some Bayer Disease Control, then mix in Manzate every four weeks as an alternate with whichever you choose - Banner Maxx or Bayer. It will keep Black Spot away for as long as you spray and follow this schedule.

More than that - we live in the days of MODERN MIRACLES when it comes to Bayer Disease Control. 10 or 20 years ago, someone would've thought it was walking on water to have a spray that could actually cure an infected BS leaf, but Bayer Disease Control (tebuconazole) does just that. The black spots will turn into dead gray spots, but the leaf will still live. That's an unbelievable achievement compared to the experience of 10 years ago and beyond.

I thought the whole deal with Knockout roses was that they weren't supposed to blackspot???

If they're the only roses in your garden that are troubled, I agree with Ingrid.
Shovel prune 'em, and plant more of what does well for you without all that hassle.

Jeri

I was thinking just what Jerijen said, amazed that Knockout roses could be decimated by blackspot. MScaradine, are your Knockouts the original Knockout, or one of the varients bred from it? Second question is: You mentioned your tea roses doing well. Did you actually mean the old garden tea roses or hybrid teas? I have just heard so many people shorten hybrid tea to "tea" that I'm never sure. They are completely separate classes of roses.

I wouldn't throw out the Knockouts without giving them a chance to recover, perhaps to next year. I had a Belinda's Dream rose that had significant blackspot when I bought it and for a few months afterwards, but after that it was highly resistant.
Thanks, Rosetom, for your information about Banner Maxx. I did not know it is the same class as the tebuconazole. I used that before I ever started with the Bayer stuff, so I still have a supply of it. I have also used manzate occasionally, so I'll remember to give that a turn every so often. I don't much care for the filmy residue the Manzate leaves behind, but that's a minor annoyance and doesn't last long. Anyway, I have not been too diligent this year about spraying, but, knock on wood, so far the blackspot has been easily controlled, so the Bayer tebuconazole is still doing its job. Yea, Modern Miracle, indeed!
I think Ingrid has a valid concern about the enivornmental impact. It is easier, though, to avoid blackspot in a drier climate. When you live in the Gulf South, blackspot is a major issue. There are certainly a handful of old garden roses highly resistant to it, but none are immune. Also, there are a lot of old garden roses that I see blackspot here as badly as modern roses. so you have to do your research carefully. I find (selfishly, perhaps) that certain colors and bloom form and size combinations are just simply not available in old garden rose varieties. I am encourage, however, with how much improvement we're seeing, in the overall disease resistance of some select modern varieties. My fingers are crossed that this trend will continue. In the meantime, if we're going to use chemicals in the garden, the labels that say CAUTION are supposed to be less dangerous than the ones that say either WARNING or DANGER. Bayer has a CAUTION label.
Mike

Thanks for all of the suggestions and sorry for the late response...

I will do what a nursery owner said to do, prune them short and naked when they are dormant (lol), then spray them and the infected soil down with sulphur and dormant oil. Hopefully this will help next year.