black spots on underside of leaves

[topshelf12]

 hello everyone,
I need to know what is causing black spots on the underside of the leaves on two of my hibs. I have used a fungicide, an incest spray, hort oil and jungle rain but they are still there. does anyone know what is causing this? sorry for the bad pic
thanks
Norm

[roadrunner]

Hi Norm, sorry really late for this reply.  Several of my plants get those every year.  There are other earlier posts on the forum about these but I don't recall that anyone has come up with any solutions for getting rid of them or know exactly what they are and what causes them.  They don't appear to be the fungus spots covered in the Hibiscus Doctor section of the website.  On some cultivars removing the infected leaves helps, others not.  Nothing I've tried has consistently worked.  Some cultivars seem to never get rid of them and slowly go down hill.  Sorry to be so vague and unhelpful.  I'm dealing with another new outbreak on several plants though most of the collection is still free of them.  My personal feeling is that spider mites are somehow involved.


dave

[topshelf12]

thanks Dave, I could not find a match on the website or past forum post for what I have. I had it on a few last year and  it didnt kill any of them. The pictures below are Creole Lady. I wiped the under side and top of each leaf with Jungle Rain about a month ago and sprayed it with copper yesterday. I hope the copper works. I know my greenhouse is too crowded and maybe on the cold side at 45 degrees some nights. Those factors probably contribute to this problem.
Norm

[Bradley]

I have the exact same thing on some of my hibiscus. Those pics, like mine, look worse than the run of the mill fungus. Several of mine got it after 3 days of misty, rainy, 40 degree weather last week. To me it almost looks like cold damage at times.