Q.Rose black spot
Chamomile tea didn’t work, aspirin with water didn’t work, but Bronide Infuse seems to be working. I didn’t treat last year (just removed the leaves). Treated and removed this year. Should I cut back the plants after blooming season and, if so, how far down? The roses are kinda naked, some more than others. I love plants but a very green gardener.
Black spot is a tough customer and is not easily stopped. The one thing I have found that will knock it down and out is called Mancozeb. This product will leave a yellowish powdery residue upon the foliage and canes of the roses but that is just part of how it works. You will likely need to repeat the spraying about 7 to 10 days apart for at least three sprayings. Keep in mind that once black spot makes its mark on the foliage it does not go away, however if the fungus has been killed the new foliage should be clean and free from the black spot. Here is a link to the mancozeb product: https://www.amazon.com/Bonide-Chemical-Mancozeb-Flowable-Fungicide/dp/B000BWZ9JO
It is also available at rosemania.com.