I realize not everyone sprays their roses for disease during the year, but if you do when you spray is as important as what you spray.
First off let me start by saying I do some liquid, foliar feeding/spraying of my roses during the year. Notice, however, the “/” mark between feeding and spraying. I use products that feed my roses nutrients designed to boost their own immune system. Like taking vitamin C during cold season, I believe in feeding my roses a preventive, balanced diet of nutrients during blackspot season. More on this in a later blog post.
When I had my rose care company in Los Angeles I found if I sprayed early in the season I had to use less of what i was using later on. As with most other things I talk about with roses, “early in the season” has nothing to do with a calendar. It has to do with nature telling us it’s time. In this case nature in the form of the roses themselves.
I do my first “spraying” when the roses start producing their first sets of tender young foliage. It might only be a few inches of growth with just three or four young burgundy tinted leaves, but that is the roses telling me it’s time.
I have consistently found over the years that by starting when this new tender growth is present, it gets the roses off to a terrific start. I often suspect it’s because this tender growth absorbs more and because the newly awakened plant is tremendously hungry or, like nutritionists say, what you put in your body first thing in the morning sets up your whole day. Or, in this case, your whole season!
So keep an eye on your roses. When you see tender growth starting to cover those canes that have lain dormant all winter, go ahead and do your first spray. Two weeks later do it again. Then relax into your normal schedule or even stretch out the time between applications. I think you’ll be pleased with the results