If you do what you’ve always done, you’ll get what you’ve always got, and this is as true for blackspot eradication on my roses as anything. Blackspot is a fungal disease that makes rose leaves go yellow, spotted with black and drop off so that the rose looks ill and bald. My rose sprayers never last very long, the spraying mechanisms stop working after just a few outings, so I end up buying a new one each year. This year I have bought one with marvellous ratings from Amazon (yes I know that’s not supporting a small business in these times), rather than just picking one up off the shelves of the local garden centre. II have also switched brands of rose disinfectant to see if it is more effective against black spot than the brand I normally use. It is quite hard to precisely compare effectiveness between brands, because the weather conditions affect how often you can spray and the amount of blackspot - it thrives in the wet and you can’t spray in teh wet. It’s much drier here than usual, so the roses ought to have less blackspot, regardless of what spray I use. Note that anti-blackspot spray is poisonous to bees, so you have to be really careful no bees are in range of the spray. That’s fine just now, because all the bees are hanging out in our kitchen.
