I use dry micronized sulfur-- probably no functional difference. It controls blackspot, rust, mildew, mites, and brown canker of stems. Blackspot control is not nearly as good as the best synthetic fungicides. However, it is adequate in an area with bad blackspot pressure if you select varieties with some resistance and if you use it faithfully.

Plants must be well watered before using sulfur. New plants from pots should be watered every day or two. Don't apply if temperatures of 94+ are forecast in the next three days.

The most viable alternatives are oils, oil plus bicarbonate, and anti-transpirants such as Wilt Pruf. Oils are even more likely to burn in hot weather. Do not use oil if you are going to use sulfur or vice versa. The combination is extremely hard on foliage.

I used copper for years and years. The best one I found was Soap Shield from Gardens Alive. It kept the disease under control with leaving the icky blue residue. I still use it for my tomatoes to keep blight at bay. I was quite happy with blackspot control from the copper until maybe 3 years ago. It seemed to quit doing as good a job in my garden around that time. I switched to Bayer Advanced. I may try going back to the copper at least part of the time now. I'm thinking maybe the BS got used to the copper and just needed to be rotated with something else.

Yes, I forgot about copper. Soap Shield is a good product. It is more toxic than the other organic products, so you need chemical-resistant gloves, and also way back I got to wondering, if I used it every week, whether I might harm the soil with an excess of it. Copper can be used in hot weather and can burn foliage in cool, drippy weather, but I don't recall that happening with Soap Shield.

Copper is very wide spectrum like mancozeb and Daconil. Unlike sulfur, it controls the "other spot" diseases like cercospora and anthracnose.

Some years back, I was thinking of using a copper soap fungicide and I made some calculations about the amount of copper which would be added to the soil. Native topsoils in Pennsylvania (the first state that came up on Google) have a total copper concentration of about 45 pounds per acre for the top 6 inches of soil. This translates into about 1/2 gram of copper per sq ft. This is the total copper, not the "plant available" copper given by a soil test, which would be a much smaller number.

If you spray Soap-Shield copper soap at the label concentration (1 ounce per gallon), once every week for a 4 month season, and spray 16 roses with 1 gallon of spray, and each rose occupies 10 sq ft of soil, and all the copper in the spray eventually gets distributed into the topsoil (Whew!), you add 0.075 grams of copper per sq ft per year.

In other words, if you use soap-shield constantly for 10 years in a typical Pennsylvania garden, you more than double the natural concentration of copper in the topsoil. Will this do any harm? I think probably not, it will probably have no effect at all on the plant available copper, but I decided it was something I didn't want to do.

Thanks, Mike.

OT-- if you have a note on how much vinegar to use as an acid buffer for mancozeb, would you post it on melz's "blackspot from hell" thread or email him. He has the dry stuff stuff.

Thanks,guys!!

i'm gonna try worm casings next year. supposedly they have a chitinase that breaks down the chitin in the fungal cell walls. if it doesn't still a good fertilizer, and organic.