Well, we all make mistakes, but that's how we learn. I don't use Daconiil anymore for any reason, but when I did use it, the temps had to be below 70 degrees. Any temps above, even in the seventies, would cause a problem. I have come to the conclusion that Daconil is strictly a cool climate item. Also, I never mixed it with anything else. That would have been overkill. Some chemicals just don't do well together. There are exceptions, of course, like Banner Maxx and Mancozeb, but not all will work well together. Another thing I have learned and that is, no matter how much rain you get before you spray, you still need to water deeply at least six hours before you spray them. Roses stress very easily in warm weather, so you want those little cells as full of moisture as possible.

I am confused about this issue. I sprayed chlorothalonil (Fertilome brand)) many times on my father's roses in central Florida in summer, without noticeable damage. He used it exclusively year round. My uncle who grew roses commercially in South Florida used it on his four acres of hybrid teas. Summer highs there are 88-94 every day. In Alabama, which is hotter than Florida, Auburn Hort uses it on their roses, and Patricia41 uses it. They report tolerable levels of damage.

I use it occasionally. I have a generic product which is around 12% chlorothalonil. If I recall correctly, the label says 2 TB for most plants, but half strength for roses. Maybe part of the disconnect has to do with different labels recommending different spray concentrations. I wouldn't worry about using it on my roses when temps of 90 are predicted, except insofar as I try to minimize the use of synthetic chemicals.

Harry, as I've said before, I was told by a pro that you can use it in high temps, but at a milder rate. God knows, I do not wish to argue this with ANYONE, just repeating what I was told. I don't know if I would use it now with the current weather here. Sorry you fried them. I love your post title.

Carla

I sprayed 12.5% chlorothalonil (2 TBS/gallon--I'm pretty sure this is the dosage I'm supposed to use, but the label has disintegrated after getting wet) on last Saturday morning, after a brief but heavy rainstorm late Friday afternoon. It had been about five days since I had done any supplemental watering, but about two weeks, I would guess, since we received any rainfall. I do try to make sure the roses have gotten somme form of water within 48 hours of spraying. I am sure that temps got up above 90 on Saturday and Sunday. I have sprayed several (three or four)times with chlorothalonil this summer. Maybe mixing it with Bayer was the problem? I have mixed it with propiconazole and not had a problem.

Harry, I have always been told not to use Daconil if the temps go over 80 degrees. I switched to mancozeb, no temp "restrictions". Ow, after JB and midge seasons, you didn't need this. Hope they come back quickly!

I wonder if it is the chlorothalonil itself or rather the inert ingredients now being used in consumer forumulations. It would probably help to know which product was used.

I have used Daconil (Ortho product) as a spring cleanup spray, at which it excelled.

A thought-- Mike_Rivers has said that chlorothalonil is extremely stable. So the stuff was still there, full strength, when Harry's garden hit 97 degrees.

Oh that is such a shame, you have had one problem on top of another it seems.....I hope you get this one under control. I purchased the Daconil in a spray bottle and it came out so thick, it was horrible! I think I will stick to just the Bayer alone. It controls blackspot great all on its own.
Good luck to you, I hope this is the last of your troubles.
six pack for breakfast....hehehe that is too funny.

I spent a lot of time in my garden over the holiday weekend. It seems that any rose leafs which had blackspot quickly yellowed and dropped. Could the spray have accelerated the demise of these weakened leafs? Many of my roses are defoliated. Others, such as Westerland, show no effects.

The good news is that all of my roses are developing a great deal of new growth and should look good in a week or so.

Everyone assumes that the problem is the Daconil, but I recently had an identical "Oh S**t" moment when I mixed Dithane, Banner Max, and the Bayer Insect & Disease product together. True to the description the leaves turned yellow and began following off. I have since gone back to just using Dithane & Banner Maxx together or the Bayer product alone.

Interestingly, I went back and sprayed everything with Messenger in a flaying attempt to recuperate for the loss and I've found the roses rebounding nicely (then again, it could have just been the granular fertilizer and the rain).

Adrian.

Years ago there was a similar discussion about Ortho's Fungunex (Triflorene). The same back and forth about yes/ no spraying in temps over 85. Then I switched to Banner Maxx+Indicate 5 in the hot summer months and the point was moot. This year however for some reason I decided to do one spraying with Fungunex during summer. The temp was 85 or a little above, hot and humid, and yup I got spray burn on the canes as well as the leaves. Roses were fully hydrated, from our unexpected monsoons, so that wasn't the problem, but maybe something else was. I've often wondered if the surfactant in the Ortho products may have some bearing on the heat issue. I guess my point is that if product A had some other ingredient that product B did not, such as a surfactant or inert ingredients (what exactly are they btw) then wouldn't brands need to be named to make sure that we are comparing the same things?

Better than my mistake about 6 years ago Harry! After a bad day at work I decided to relax by spraying the roses. When I noticed a lot of wilting the next day I realized I had sprayed with weed killer and not fungicide. Believe it or not, some roses actually pulled through and will NEVER get SP'ED regardless of how they look (JFK was one of the roses that survived).

"(what exactly are they btw)"

Maryl, inerts and surfactants are defined as trade secrets under the labeling regulations, so the public has no way to know. I think there may well be differences in the phytotoxicity (or even the human toxicity) of different brands of the same active ingredient. I recall years back in American Rose, someone was running full page ads for a chlorothalonil product they claimed was easier on the rose foliage than competing products.

(Chlorothalonil is the generic name for the chemical often labeled as Daconil.)

"What are the guidelines for Daconil use?"

Don't use it, use Bayer instead.

I guess I'm wondering why we all aren't just using Bayer. This is the best year I have had BS-wise, and I think it all has to do with switching to the Bayer product.

Which Bayer product? I've only used the insecticide.

The original problem was that he had blackspot and used products that would not kill the blackspot spores. Then everybody got off on Daconil use which is not helping this poor man take care of his problem. A few people said they used Manzate but didn't recommend it to be used for his blackspot problem. Manzate which is a combination of zinc and managanese IS THE ONLY PRODUCT THAT WILL KILL THE BLACKSPOT SPORES!!! The other products just protect, they won't cure the problem. First use Manzate three times a week for three weeks. That will cleanup the active spores. Since you have some new leaves coming on go ahead and mix a preventive with it. I like Banner Max of Bayer Rose Disease Control. That will take care of your blackspot problem and keep it controled.
I guess we learn by trial and error. By the way did the label tell you to mix the two??? If it's not on the label don't do it, that's why the label is there to start.

sybl--the Bayer product being discussed is Bayer Advanced Garden Disease Control for Flowers, Roses, and Shrubs. It is just a fungicide--no dangerous insecticides mixed in with it as too many of the other Bayer products have done.

Kate

dan,
Sorry, and I do not want to start an arguement, but you are most definitely mistaken on your claim on Manzate. there has been enough studies done now to prove that Tebuconazole cures BS to just ignore. Here is a link to a previous discussion. Open the pdf MichaelG provided and read through it. there are many more studies out there showing the same results.

Here is a link that might be useful: Previous Thread on BS

Thanks mgleason56, I've used the Bayer Rose Disease Control every since the Rose Day at Lowes. I wanted to try the Bayer product since we were supposed to recommend it. I can't say that it cures blackspot that well, that's why I started using Manzate. That product did! So I mix the two as I spray and my bushes are clean!

Dan, I am sure Bayer and mancozeb make a very effective spray, but perhaps not for the reasons you are saying.

"Contact fungicides are also known as protectants and pre-infection chemicals. They remain on the plant surface, and they need to be present before the infection occurs. . . . Some examples of contact chemicals are mancozeb, maneb, chlorothalonil, captan, and copper formulations. . . ."

See also what the CR manual says about how mancozeb works. It is a surface protectant, preventative fungicide. Rosemania's version isn't true.

What I was saying is the Manzate cleaned up the blackspot problem where nothing else did. I know the classes of fungicides like Bayer is systemic and Daconil and Manzate is not. I teach CR schools so I know what's in the book, but I also know what works.

Daconil always destroyed the leaves on my roses down here, no matter what, so when I was actively spraying I stopped using it. The roses just did not like it. Banner Max and Manzate never harmed them, although many of the OGR didn't like any sprays of any sort.

Now I have almost all OGR and don't care to spray ever again. Well, maybe if something unusual was going on, but otherwise no.

Sandy