Rather than spend time, energy, and money spraying stuff around to try to prevent my roses, or other plants, from becoming infected with plant diseases or being bothered by insect pests I grow them in a good healthy soil that is well amended with organic matter, and periodically tested for nutrient balance, so the only time I need concern myself with these problems is when I bring a new rose in form the nursery.

I've used it, and I think it gives reasonably good control of insect pests such as aphids. Some roses might have their leaves burned by it, so it should be used with caution on certain cultivars.

Hard to tell if it was effective on blackspot.