How well has the sulfur application worked so far?

You're better off using Bonide Mancozeb, much better product for blackspot.

Sulfur has a long history (more than 2000 years!) as an effective fungicide and is still highly rated as preventative for black spot, rust and powdery mildew on roses. It is still one of the primary weapons in many gardeners' plant disease arsenal and especially those that favor more natural, environmentally friendly controls.

I'd look at a wettable sulfur product likethis, as spraying the product is going to provide much better coverage and control than just dusting. It is also much less expensive than mancozeb, which btw is restricted from sale in a number of states.

Thank you Henry it is getting somewhat difficult these days to access safety data on many chemicals. I for one appreciate at least having access to the information.

re: How well has the sulfur application worked so far?

It's early, but there's been a big improvement over last year (which was only my second year with the roses, and I naively let nature runs its course the first few months). I've been much more diligent this year; when rain is forecast, I douse them pretty heavy with the sulfur-copper powder a few days ahead of time. It doesn't seem to stunt new growth. I also use chlorothalonil (Daconil) more often than last year. And now I check for yellowing speckled leaves every day, and shake off the upper branches after rain or dew. I still get about a dozen affected leaves every week, whereas last year it seems like I had to remove close to half the leaves.

chlorothalonil- what precautions do you take to protect honey bees? What about the cancer risk?

http://ipm.ucanr.edu/TOOLS/PNAI/pnaishow.php?id=21

Impact on Honey Bees3

• Toxicity category: II - Apply only during late evening
• 
  
• EPA: Likely to be carcinogenic to humans
  

Good info, thank you Henry. In my old age I can get a bit careless about personal exposure. Can ortho-phenylphenol be used instead?

I worked in an analytical chemistry lab and we found chlorothalonil residue in many foods, as well as its breakdown products. Ingesting a couple micrograms or parts-per-million is probably not the same as inhaling the 0.087% concentration mist.

I've never seen honeybees pollinating or collecting nectar from roses in my backyard, and of course I don't use neonicotinoids - yet I feel guilty nonetheless.

On a lighter note (and I apologize to everyone in advance) - Let us not forget the ubiquitous hydrogen hydroxide which causes a large number of deaths in all species, and is a major cause of environmental and property damage. BTW, honey was a good source of calories back in the cave man days, but now we have much more sanitary ways to harvest sugar that don't involve raiding honeycombs filled with insect regurg...

Regarding the use of ortho-phenylphenol to control blackspot on roses. I am not familiar with such a use. I did not even find that it is registered for such use. Do you know of such a registration?

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Here is a general link:

https://toxnet.nlm.nih.gov/cgi-bin/sis/search2/f?./temp/~PlEFM1:1

anyone else have luck with the sulfur? Dan, have you tried some of the new disease resistant roses that dont need as many chemicals? I recommend Wedding Bells. It can be grown with out pesticides and has the most beautiful blooms.

re: "Regarding the use of ortho-phenylphenol to control blackspot on roses. I am not familiar with such a use. I did not even find that it is registered for such use. Do you know of such a registration? "

Well, I brought it up because it's one of the least toxic (and most widely used) fungicides that are already approved for use on food crops for human consumption. Probably wishful thinking on my part as far as blackspot prevention. It's allowed on lots of food crops, notably citrus. If you've noticed, oranges and grapefruit that come in mesh bags or boxes actually list which pesticides were applied, more often than not. (usually thiabendazole, imazilil, and o-phenylphenol under its various names.) It's applied post-harvest to delay/retard/postpone mold growth. Of the roughly 500 'approved pesticides' it has one of the highest tolerances (i.e. it's allowed at higher levels than most others, often >20 ppm). Most of it stays on the citrus peel exterior, so there's not much in orange juice etc.

It's a phenolic compound with no chlorines or other halogens, not an organophosphate, not a triazine etc. And being a phenol, it's an organic chemical compound, at least in strict Chemistry terminology.

(Please note, I did not state it was 100% safe and completely harmless.)

It was the active ingredient in Lysol (and Amphyl) for many years, and it didn't generate a lot of adverse events or reports. Over the years they switch from phenols to Quats and other disinfectant antiseptics.

If it worked on blackspot, we'd have heard about it by now (from UC extension and the thousands of other groups).

Back to the subject of chlorthalonil - thanks for pointing out the "Apply only during late evening" admonition. I hadn't heard of it but will now dutifully adhere.

re: "anyone else have luck with the sulfur? Dan, have you tried some of the new disease resistant roses that dont need as many chemicals? I recommend Wedding Bells. It can be grown with out pesticides and has the most beautiful blooms."

Thank you SoFL Rose. Yes, I am aiming in that direction starting this (my third) year. I'm enamored of the classic rose scents, and when shopping at the nurseries and stores, every plant with aromas I liked were hybrid teas. (e.g. Oklahoma, Chrysler Imp, Mr Lincoln, Tiffany) I've looked at some previous threads here to see which Antique and other healthier non-HT's might possess similar fragrances.

I usually don't use the chemicals much, unless ants get in the house or wasps build near the door. But for roses I am making an exception these first couple years. My first few sulfur applications have been heavy-handed, and I'll have to taper off (assuming I make it through the month).

The Wedding Bells look interesting, especially if the description "Moderately Fragrant" is accurate. I like that color, especially on overcast or foggy days when the sun isn't at full throttle.

Hmm, I have to admit my Wedding Bells does not have much fragrance. Beverly on the other hand is insanely fragrant and very good with disease resistance. I find Chrysler Imperial has pretty good disease resistance for a hybrid tea too. Another good one is Double Delight. It may need occasional application of fungicide, but its better than most in the resistant department when it comes to hybrid teas. Also try Sugar Moon. That has to be my most fragrant rose and it too is not bad when it comes to disease considering.

Tiffany is pretty good too when it comes to disease. Unfortunately the more fragrant they are the more disease prone they seem to be!

Kordes has a parfuma collection that has some nice fragrance, but unfortunately, I havent had much luck with any of them. My summer Romance never bloomed, Earth Angel same story, my First Crush was actually disease prone.

Oh and i'm trying dark desire now, just go it. will let you know. :)

Since I moved to deer country I can't have roses anymore, but I used to control black spot by pruning all the blackspots back, covering the soil with corn meal, and covering that with mulch. Then every month I redid the corn meal to help fertilize and to keep the black spot away.