I know this topic comes up every year and for those of you who are tired of the question, I am sorry. I did the search and still did not find exactly the information I am searching.
I am once again battleing late summer blackspot. I have tried the baking soda/oil mixture and haven't been impressed. I am wondering what my next step is. (I know picking blackspot-resistant roses will be suggested, and I have some, but at this point, I just want to keep some leaves on my other less-resistant roses.)
I worked this weekend at changing my sprinkler system to a drip system, but I am wondering what SPECIFICALLY works to combat that blackspot. Those of you who spray, what specifically do you use, how often, etc. Also, we have hives in the area, so I don't want to use anything that might harm the bees, just the blackspot. Those of you that don't spray, what do you use, how often, etc.?
In my internet research, I saw people recommending potash as a potential blackspot deterrent. Does anyone do this? If so, where do you get it, how and how often do you apply?
Thanks in advance.