One of my daisy plants turned black and looked like it had been burned. Then, I bought a new hydrangea, and it started looking the same way. I pruned the affected parts but now the new shoots are growing back brown instead of green. I also tried spraying with a fungicide/miticide for about a week after I noticed the blackness moving in. AND, several plants near it now have the same blackness starting on their leaves and their flowers are not coming in. The black seems to start right along the outer edge of the leaves and works its way in, eventually turning the existing flowers black as well. HELP!!! These are all perennials, too, so should I even expect them to come back next year?
Leaves of Plants Look Black, Burnt
Certified GKH Gardening Expert
It could be either black spot or sooty mold. Both are treatable and in most cases, not fatal to the plants. These articles will help:
(this is about black spot on roses, but it applies to all plants) https://www.gardeningknowhow.com/ornamental/flowers/roses/black-spot-roses.htm