We put this through it's most enduring test possible - a large rose garden in Washington D.C. Washington is one of those cities where the garden clubs gave up their rose shows years ago because roses are nearly impossible to grow here. It's the black-spot capital in addition to the Nation's Capital. (Although the WRS and ARS still operate.)
Recommend this product?
Bugs - it will knock aphids and other bugs off easily. Works like a charm. For the more determined Japanese Beetles - this is not worth it. Stick with Seven Dust.
Fungal infections - because it is so humid and rains so much here, you have to spray the tops and bottoms of every leaf at least once a week. Anything less and your rose bush looks like a shaved poodle by July.
There are new "all-in-one" treatments available since 2005, and initial tests have proven pretty impressive. Bayer for one might be a better alternative to the endless spraying.