Black eyed Susan or cone flowers black spots on leaves

Question: Please reference leaves from my black-eyed Susan flowers, maybe cone flowers ? There are black spots on the leaves ..photos attached.  Can you advise what needs to be done to resolve these issues ....thank you. Roland G Pezold <personal data hidden>

responder: Thank you for your question! Rebecca Finneran Michigan State University Extension Senior Horticulture Educator Learn how t be a Smart Gardener here www.migarden.msu.edu Replied July 12, 2023, 8:12 AM EDT
response: You might think this spot is caused by a disease such as a leaf spot fungi, however if you look closely, each blackish spot has a raised bump in the middle.  This is actually caused by an insect (Psyllid).  Here is some more information on this pest.  Control strategies are also listed here: https://content.ces.ncsu.edu/rudbeckia-triozid

responder: The Question Asker Replied July 12, 2023, 8:03 PM EDT
response: Thank you for your response, I appreciate it. Can you give me a recommendation as to what type of spray should be used to control this fungi ?

responder: Thank you for your question! Rebecca Finneran Michigan State University Extension Senior Horticulture Educator Learn how t be a Smart Gardener here www.migarden.msu.edu Replied July 13, 2023, 7:52 AM EDT
response: Rudbeckia triozid nymphs are heavily parasitized (over 90 percent) by a very small black and red wasp in Michigan, something that is likely to occur in North Carolina as well. So the population is likely to collapse even if nothing is done. Should there be an overwhelming desire to spray, it is unlikely that the rudbeckia triozid has developed resistance to insecticides. Because the nymphs disrupt leaf tissue so profoundly, systemic insecticides may not work as well. Most insecticides labeled for landscape use found in plant sections of big box stores, nurseries, and garden centers should give more than adequate control as long as the spray is directed upward onto the lower leaf surfaces where the nymphs feed.  - My recommendation is to wait it out.  This will not harm the plant.

responder: The Question Asker Replied July 22, 2023, 4:51 PM EDT
response: Regarding your reply, I would appreciate if I could ask one more question.   Our local garden shop said I have “Siptoria Leafspot” and recommended I should treat this problem with FUNGON OIL ? I am confused as to what to do, the treatments for spraying are very difficult, also to spray “under” the leaf ?? Appreciate your thoughts, especially if I do nothing as you suggested but do not want to lose my nice flowers. Thank you …Roland G Pezold From: ask=<personal data hidden> <ask=<personal data hidden>> On Behalf Of Ask ExtensionSent: Thursday, July 13, 2023 7:52 AMTo: Roland Pezold <<personal data hidden>>Subject: Re: Black eyed Susan or cone flowers black spots on leaves (#0110060)

responder: Thank you for your question! Rebecca Finneran Michigan State University Extension Senior Horticulture Educator Learn how t be a Smart Gardener here www.migarden.msu.edu Replied July 22, 2023, 6:08 PM EDT
response: Of course, a casual look would make a person think this was Septoria leaf spot, but as I mentioned earlier—look at the little bump in the middle of the spot.  That indicates insect.  The other thing you will notice is that the spots are actually a deep purple—not black.  I have attached an article on Septoria so you can compare.  NO fungicides are needed.  https://www.canr.msu.edu/resources/septoria-leaf-spot

responder: The Question Asker Replied July 23, 2023, 10:06 AM EDT
response: I truly appreciate your quick reply. Thank you. We are happy that both our daughters graduated from MSU and today will visit our granddaughter who is in her last year of Neuroscience. Best regards, Roland G Pezold From: ask=<personal data hidden> <ask=<personal data hidden>> On Behalf Of Ask ExtensionSent: Saturday, July 22, 2023 6:09 PMTo: Roland Pezold <<personal data hidden>>Subject: Re: Black eyed Susan or cone flowers black spots on leaves (#0110060)

responder: Thank you for your question! Rebecca Finneran Michigan State University Extension Senior Horticulture Educator Learn how t be a Smart Gardener here www.migarden.msu.edu Replied July 24, 2023, 4:54 PM EDT
response: Yay!  Go green.  :)