I have 12 rose bushes, plus 3 climbers, that are all covered in black spot. They are planted in a gravel garden so it's very hard to pick up every dead leaf. I have tried every remedy known to man without any success, other than digging them all up. I'm stuck as what to try next. Any ideas?
Black Spot on Roses
Certified GKH Gardening Expert
A series of spray applications of a fungicide called Mancozeb will usually stop black spot in its tracks. This article should help as well: https://www.gardeningknowhow.com/ornamental/flowers/roses/black-spot-roses.htm
The best thing I have found to use to get control on Black Spot is a product called Mancozeb. I got mine at http://www.rosemania.com . Spraying the rosebushes with it at 7 to 10 day intervals will likely be required for a big black spot problem. It does leave a yellowish powdery residue on the foliage as that is part of how it works. Keep in mind that the black spots from he black spot fungus do not go away. If killed by the spraying though, the new foliage should be clear of the black spots. Here is an article for you too: https://www.gardeningknowhow.com/ornamental/flowers/roses/black-spot-roses.htm