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JennyC
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Joined: Thu May 15, 2008 2:25 pm
Location: NW Georgia

Black spot fungus on very established rose bush

I have a very large, well established bush in my front yard. It's a pink cabbage rose, and the bush is roughly four feet in diameter and five feet high. Last summer it was thriving, and earlier this summer as well. It's been fighting black spot fungus for a while now, though. It loses leaves and blooms, puts up new growth, has leaves and blooms on that for a while, repeat. I hoped it would manage to beat the fungus; obviously, it's been here for years with no tending whatsoever, and I'm almost afraid to do anything because it so clearly has it own system worked out. But I'm becoming convinced it won't win this battle on its own.

What can I do to help? Will the fungus die over the winter? and my real puzzle: where could the fungus have come from? This bush is fairly well isolated in the middle of the lawn, and none of the other roses here have a problem.

doccat5
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Location: VA

Black spot is an airborne fungus. Usually aggravated by humidity and lots of wet. Once it's in the soil, it's almost impossible to get rid of, but you can get it under control.
I used a couple of handfuls of corn meal around my Hteas with which I have a running black spot battle and it helped a great deal. At least I have much less showing up on the leaves now than I did.

There is also a organic spray using skim milk, I'll try and see if I can find the recipe for that. It evidently acts as a fungicide and helps slow it down. You'll never get rid of it all, but you can certainly keep it manageable.

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JennyC
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Location: NW Georgia

Thanks, doccat! Corn meal, huh? On the ground around the base of the plant?

If you find that recipe, please do post it as well.

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JennyC
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Joined: Thu May 15, 2008 2:25 pm
Location: NW Georgia

I tried the corn meal a few weeks ago and it has helped tremendously! Thanks, Doccat!

Do you know the mechanism for that? (What makes it work?)

JPIXI
Senior Member
Posts: 213
Joined: Mon Jul 04, 2005 7:54 am
Location: France, Paris

Hi JennyC,

Blaxkspot is a persistence problem for rose gardener. As a precaution, you can find out more on Espom Salt as periodic spray. It can strengthen your rose and largely reduce the blackspot from coming back.

Amitié,
Pixi

elks240
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Joined: Sat Sep 27, 2008 5:32 pm
Location: Midwest City, Oklahoma

Hello, I am new to the forum and new to roses. I have two bushes out front and both ( just this year ) started to get what appears to be the same as blackspot. See photo below... I just want to make sure that this is black spot that I am battling. I have used Bayer all in one plant care and it is supposed to fight the black spot but haven't seen any results. I will try these methods you have stated in this thread. Thanks for the confirmation.... or not lol.

[img]https://i194.photobucket.com/albums/z77/elks240/DSC02890-1.jpg[/img]

cynthia_h
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Location: El Cerrito, CA

Welcome to the Helpful Gardener, elks.

Sorry, but yes you have black spot, as seen in the photo.

I don't know anything about conventional gardening/rose care (I.e., with the usual array of chemicals). I have always used organic or nearly organic methods.

So...I am also battling black spot, powdery mildew, rust, etc. on my roses. They got away from me a couple of times this year.

We started with neem oil spray, but that biweekly schedule went down the tubes. Too bad, because it seemed to be helping.

After my current deadheading and worm-tea fertilization of the roses, I'm just going to give them water until they die back this December or so. Then I will rake the absolute daylights out from under them (many rose diseases/ailments overwinter in the rose litter on the ground), treat them with dormant sulfur & horticultural oil, and prune the living *you know what :wink:* out of them. Due to personal health difficulties, I didn't perform this service last year or the year before that or the year before that...for quite a few years.

So we shall see...

Will probably use neem again next spring as a preventive, assuming the sulfur/clean-up/pruning gets me off to a good start.

Also, I'm sure you know this: do not work the plants when they are wet or damp. Clean your tools between plants (I.e., minimize the chances of YOU transferring pathogens from plant to plant; let the wind/insects/whatever do that for you :lol:). When I cut out powdery mildew or black spot, I'm careful to hold the about-to-be-removed plant part with my off hand and cut with my good hand. I do *not* touch any "good" parts of the plants with my "contaminated" hand or glove.

Maybe some of this rambling is useful to you or others?

Cynthia H.
USDA Zone 9, Sunset Zone 17

elks240
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Joined: Sat Sep 27, 2008 5:32 pm
Location: Midwest City, Oklahoma

Thank you Cynthia I will prune it out well this winter and remove the cedar chips I put in this spring.( I have a feeling they aren't helping ). Cynthia is my wifes name lol. Also My wife is originally from Serritos, California hahahah small world.... kind of.

Thanks again, John



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