I find it so common that what we think we know as fact is constantly changing. Now you would think with all the money and time spent on studying black spot on roses there would at least be a consensus on such a basic thing as whether or not the dead leaves with black spot are or are not a future source of infection. Even that seems to be still in controversy. I live in black spot central I think, almost all roses here seem to get it to some degree. I have had almost no luck with any of the above mentioned sprays. They may work in areas where black spot is only a slight problem, but not here. Now I have learned that I can seldom attribute any action I take to any event with my plants. It is so easy to assume that if I have black spot and I spray with something and the black spot goes away, then the spray must have worked. Too often it was just a climate change, of some unknown that actually destroyed the black spot, maybe even the plant itself resisted it. I was thinking about the possibility of using a vacuum to suck all the infected leaves off, avoiding the thorns and all the stooping, but that might seriously damage the plant. I was out picking off black spot infected leaves today, some of them I really had to tug on and jerk to get them off, but on one rose I think I could have shaken the bush and they all would just have fallen to the ground.
Now not long ago when black spot was just beginning to show and starting to look like a serious problem on several of the plants I used Bayer 3 in one rose granules, and now the new growth is coming on and the black spot is almost vanished. I used the product three years ago with the same effect, I used sprays the past two years and just ended up with burnt leaves with black spot. Baking soda and milk sprays were of no use at all.
I have tried to grow roses and vegetables organically, but obviously I am not knowledgeable or energetic enough to constantly battle disease and pests organically, so I have had to resort to using chemicals. Most organic solutions I have tried have totally failed. Organic solutions for squash bugs and borers and organic solutions for black spot require way more time and dedication to a few plants than I have. Slugs and snails, whiteflies and aphids I can get by with organic solutions most of the time. I am just saying that for me some battles need heavy artillery and others can be fought with lighter armament.
