Is this black spot?

13 years ago

Hey Folks,

I'm new to rose growing and this is my first post here. I planted 10 KO roses in a front bed in March. They were straight from the grower, lush healthy and full of blooms/buds. They get lots of sun and late afternoon shade. Nice airy location with new drip irrigation. I fertilized at planting with Rosetone (haven't since). Had a small bout with aphids in May- released lady bugs which controlled a bit, but didn't stay in garden. I also deadheaded a bit.

So, with the heat and the afternoon rains I'm noticing yellowing, spotted decaying leaves at the bottom interior of the plant. Is this black spot? (See photo)

Also, I fear I may have planted these guys too close. When would be the best time to move a couple if I was going too? Wait for dormant season or do it now while it can still put roots down?

Thanks,
Mike

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Comments (8)

SoFL Rose z10
13 years ago
Yes I believe that is what you are dealing with.
jim1961 Central Pennsylvania Zone 6a
13 years ago
Can you take a closer more clearer pic of some of your effected rose leaves?
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mike_rivers
13 years ago
It doesn't really look like blackspot to me. Check this link to downy mildew and see how it matches.

Here is a link that might be useful: Downy Mildew
mike_rivers
13 years ago
It doesn't really look like blackspot to me. Check this link to downy mildew and see how it matches.

Here is a link that might be useful: Downy Mildew
michaelg
13 years ago
Pictures aren't clear enough to diagnose, but that much blackspot on KO is close to impossible. Also I don't think you could have downy mildew in Florida in summer. KO is susceptible to cercospora disease. Last summer I saw a plant that looked about like yours because of cercospora. It is a disease of mild weather, but it takes a couple of months for the leaves to yellow and die. Picking off spotted leaves would probably give adequate control.

Here is info from U of F.

Here is a link that might be useful: cercospora from ifas
jerijen
13 years ago
Better/clearer images might be helpful, but I think I see some cercospora. Maybe, also some worn out leaves.

FWIW, I have heard that there are some strains of blackspot to which KO is not immune (no suprise there!).

Jeri
diane_nj 6b/7a
13 years ago
Are they only at the bottom of the plant? Is is speading? Are they on all plants? They could be the plant shedding old leaves, which will sometimes show disease because they are weak.

On the moving, moving while dormant is always preferred, but if you have to do it sooner, go for it.
mzstitch
13 years ago
I'm doubting blackspot as well. I have alot of experience with blackspot on my roses here in 7b S.C. May I ask if you have sprayed these roses with anything recently, or sprayed around them?