worried about this returning to my Black eyed susans this year

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kbkar Madison, NH Apr 08, 2021

Last year this problem overwhelmed my black - eyed susans and also infected adjacent coneflowers. It's like a black inky stain with green bumps in the middle of each.
I tried removing the infected leaves and I used insecticidal soap but I think it was too late by then. Will this issue return this year? Should I spray the plants now with the insecticidal soap? The flowers are beginning to show their early spring growth and some of the leaves are a little dark already. HELP! PLEASE! Love these flowers.


This message was edited Apr 12, 2021 9:17 AM

This message was edited Apr 12, 2021 9:26 AM

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kbkar Madison, NH Apr 12, 2021

Hoping for a reply by now.

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AAgeorge Severna Park, MD Apr 06, 2022

Insecticidal soap has some anti-fungal benefit, but it is minimal. You shouldn't be surprised that fungicides are more effective. However, no fungicide is likely to cure entrenched fungus. Instead, they prevent or minimize fungal development. Most fungus does winter over, so remove and trash dead foliage, and follow label with spraying at first sight of growth in spring. You might be able to send a pic to a brand like Bonide for id and recommended product, but there are many different funguses.

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ZilyZily Castro Valley, CA Apr 06, 2022

These articles may help.
https://www.melindamyers.com/articles/spots-on-leaves-of-black-eyed-susan

https://extension.umn.edu/plant-diseases/leaf-spot-diseases-trees-and-shrubs

https://www.gardentech.com/disease/black-spot

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AAgeorge Severna Park, MD Apr 07, 2022

I'm not expert, but should have mentioned my first guess would be septoria leaf spot. If so, copper is a treatment.

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