My endless summer hydrangea are losing their leaves

[Adrienne]

I'm new to gardening and planted a lot this year! Many plants are doing really well and it has been rewarding to watch everything thriving. However, three smallish endless summer hydrangea I planted on the side of my house, this spring, sort of out of my attention, got what I think is black spot. I probably under and over watered them a couple times, maybe stressing the plants -( it is REALLY hot right now here). I treated them about a week ago by spraying with Bayer Advanced Disease Control for roses, flowers and shrubs. I thought this would fix things. My husband used a fungicide on the grass, which may have gotten on the plants (but the bag of fungicide doesn't indicate that it is hurtful to flowering shrubs). Anyway, I just took a look at the plants and the leaves - perfectly good green leaves - are just falling off the plant. I ended up cutting one of the plants almost completely back, so now there are only some ugly twigs where once I had a plant. Ugh. What should I do now? Pull it up and start over? The other plants don't have the same degree of leaf drop, but it is happening to all of them!

[luis_pr]

Could you post a picture to be sure? There are some fungal infections and mineral deficiencies that the leaves could show and a picture may help.

[rainbowgardener]

What made you think it had blackspot? I think Blackspot, Diplocarpon rosae, is a fungal disease mainly of rose bushes. But hydrangeas have their own leaf spot fungal diseases they are prone to. Cercospora leaf spot is one of them:
https://apps.caes.uga.edu/urbanag/home&g ... oryid=2773

but there are others. Luis is right that pictures might help.

Also, do clean up the fallen leaves and get rid of them. If it is a fungal disease, those leaves can keep spreading it.