Roses forum: BEST effective spray etc for Blackspot?

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Name: Bridget
Baton Rouge, LA (Zone 9a)
C’est la vie .........
Berrycajun
Feb 5, 2020 5:35 PM CST
It's been SO rainy and cloudy down here in South Louisiana that my roses are all getting Blackspot. :(

My new dawns are absolutely hideous right now. They look awfully frightful— like something scary for Halloween — EVERY single leaf on both of my new dawns is an bright orangey-gold with big black spots. And the plants are pretty bare, so their mean thorns snarl at you.

My Sally Holmes is getting it. I woke up this morning and was so upset to see yellow leaves on her. Iceberg, Peggy Martin, and coral drift have it too now. :(

I've never treated Blackspot before. I have used Bayer rose 3 in 1systemic but it was for pests not Blackspot.

What is the BEST treatment for Blackspot? I'd like to nip it in the bud - no pun intended - as quickly as possible.

Thanks!
After all, tomorrow is another day!
— Katie Scarlett O’Hara
Name: seil
St Clair Shores, MI (Zone 6a)
Roses Garden Photography Region: Michigan
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seilMI
Feb 5, 2020 5:50 PM CST
There are over a hundred different strains of black spot as well as several other fungal diseases that cause spotting. You need to diagnose exactly what you are dealing with first. What works here on my strain may not work on yours. Best bet is to get an accurate diagnosis and then talk to a local rose society on what works best in your area for that disease.

I will tell you that most rosarians do not recommend the 3 in 1 products. When you combine all those things in one they tend to be diluted down versions and are less effective. Also if you have BS but not pests you're wasting the insecticide and it could be killing the good bugs that you need in your garden. Also there are much better fertilizers. You can control the amount each rose is getting much better by using just a good quality rose fertilizer when you need it. Not all fungicides are effective on all fungal diseases. You need the one that works on the specific disease you have. 3 in 1's are easy and cheap but not the best choice for your roses.
Name: Porkpal
Richmond, TX
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porkpal
Feb 5, 2020 7:18 PM CST
Many of my roses have leaves that look as you describe. I am not going to worry about them as those leaves will soon be shed and new, healthy spring ones will take over. I never spray anything on anyone . The weaker roses have some black spot in the spring but recover and do okay.
Porkpal
Name: Zuzu
Northern California (Zone 9a)
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zuzu
Feb 5, 2020 7:46 PM CST

Moderator

I'm with Porkpal. I never spray anything in my garden and I don't care how unsightly the leaves can become. Unsightly leaves soon fall off and are replaced by lovely new leaves.
Name: Bridget
Baton Rouge, LA (Zone 9a)
C’est la vie .........
Berrycajun
Feb 5, 2020 8:28 PM CST
seilMI said:There are over a hundred different strains of black spot as well as several other fungal diseases that cause spotting. You need to diagnose exactly what you are dealing with first. What works here on my strain may not work on yours. Best bet is to get an accurate diagnosis and then talk to a local rose society on what works best in your area for that disease.

I will tell you that most rosarians do not recommend the 3 in 1 products. When you combine all those things in one they tend to be diluted down versions and are less effective. Also if you have BS but not pests you're wasting the insecticide and it could be killing the good bugs that you need in your garden. Also there are much better fertilizers. You can control the amount each rose is getting much better by using just a good quality rose fertilizer when you need it. Not all fungicides are effective on all fungal diseases. You need the one that works on the specific disease you have. 3 in 1's are easy and cheap but not the best choice for your roses.


Yes. I totally agree regarding the 3 in 1. That was several years ago before i knew better.

After all, tomorrow is another day!
— Katie Scarlett O’Hara
Name: Bridget
Baton Rouge, LA (Zone 9a)
C’est la vie .........
Berrycajun
Feb 5, 2020 8:36 PM CST
zuzu said:I'm with Porkpal. I never spray anything in my garden and I don't care how unsightly the leaves can become. Unsightly leaves soon fall off and are replaced by lovely new leaves.


Ok. Thx. This Spray thing is new for me. I have never sprayed before and everything does well enough as long as i give compost and worm castings and mulch. I usually don't mind the typical yellow leaves that flop off easily as i know it's natural to drop leaves. I just assumed that this was a really bad case of Blackspot and that it would eventually kill my roses. I just read about a baking soda solution spray and a milk solution spray??? (There's a recipe for each one - a water ratio)

I can ride it out if i know this Blackspot won't kill all my roses. I have quite a few that are healthy still. I'm fine with the others looking raggedy for a while if I know they will recover.
After all, tomorrow is another day!
— Katie Scarlett O’Hara
SoCal (Zone 10a)
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SoCalGardenNut
Feb 5, 2020 8:55 PM CST
I've been removing ugly leaves today. It turns out they have rose rust problem, I didn't know that. But I noticed young buds are pushing up. So it's ok to remove the leaves. Same with black spots leaves. I just removed them. They are ugly as is. I want nice green leaves.
But I dumped the leaves. I leave no decaying leaves on the ground, they harboring pests.
[Last edited by SoCalGardenNut - Feb 5, 2020 8:56 PM (+)]
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Name: Bridget
Baton Rouge, LA (Zone 9a)
C’est la vie .........
Berrycajun
Feb 5, 2020 9:20 PM CST
SoCalGardenNut said:I've been removing ugly leaves today. It turns out they have rose rust problem, I didn't know that. But I noticed young buds are pushing up. So it's ok to remove the leaves. Same with black spots leaves. I just removed them. They are ugly as is. I want nice green leaves.
But I dumped the leaves. I leave no decaying leaves on the ground, they harboring pests.


I'll try removing the ugly leaves and throwing them out with the trash. I will be giving them Organic food this weekend and remulching with pine straw for spring. Hopefully things will improve. If they don't, I'll try the milk recipe 🤷🏻‍♀️. Something about changing the pH with milk - the fungus spores need a certain pH and milk alters that. I'm figuring milk can't hurt any beneficials, right?

After all, tomorrow is another day!
— Katie Scarlett O’Hara
SoCal (Zone 10a)
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SoCalGardenNut
Feb 5, 2020 9:45 PM CST
I need to do research in this. My husband might not want me to use his milk that way. Lol.
Name: seil
St Clair Shores, MI (Zone 6a)
Roses Garden Photography Region: Michigan
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seilMI
Feb 5, 2020 10:29 PM CST
Be very careful with home recipes. Especially if they contain any kind of oil. It's very easy to burn your leaves in a hot sunny climate.
Name: Lynda Horn
Arkansas (Zone 7b)
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gardenfish
Feb 7, 2020 5:51 AM CST
I live in Arkansas where black spot is endemic. The best advise I ever received was from a very knowledgeable horticulturist here. She said to keep all leaves picked up and disposed of, and to change the mulch underneath every year, about the time that you cut them back, and apply fungicide to the ground around the shrubs. She also suggested the Bayer systemic, but I agree with seilMI, stuff is no good, and possibly dangerous to bees. Since I am organic, I used copper last year and had moderate to good success at controlling the black spot. The key word here is control; you can't eradicate it, only control it. I also used copper on my tomatoes which had septoria leaf spot. I have had one rose that was so weakened by black spot that I am sure that the black spot hastened it's demise.
“ Be kind whenever possible”
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Dixie3rose
Feb 9, 2020 7:13 AM CST
Black spot is also a leaf spot disease that is best prevented. Forget about milk or baking soda being an effective control, studies show that below the upper parts of the US it doesn't work. Copper is somewhat effective, so are products with myclobutanil, which is a systemic fungicide, and combine it with Mancozeb, which is contact fungicide. If you spray Mancozeb three times, three days apart, spray ground and old leaf debris, and this will get black spot under control. Don't forget about contacting the American Rose Society [email protected], and look up a Consulting Rosarian for advice too. There was a new organic product I saw at a recent ARS national convention called Rose Shield. The company gave out free spray samples. Will try it and hope it works. I'm in the northeast side of South Carolina.
Name: Bridget
Baton Rouge, LA (Zone 9a)
C’est la vie .........
Berrycajun
Feb 9, 2020 1:08 PM CST
SoCalGardenNut said:I've been removing ugly leaves today. It turns out they have rose rust problem, I didn't know that. But I noticed young buds are pushing up. So it's ok to remove the leaves. Same with black spots leaves. I just removed them. They are ugly as is. I want nice green leaves.
But I dumped the leaves. I leave no decaying leaves on the ground, they harboring pests.


I'll try removing the ugly leaves and throwing them out with the trash. I will be giving them Organic food this weekend and remulching with pine straw for spring. Hopefully things will improve. If they don't, I'll try the milk recipe 🤷🏻‍♀️. Something about changing the pH with milk - the fungus spores need a certain pH and milk alters that. I'm figuring milk can't hurt any beneficials, right?

After all, tomorrow is another day!
— Katie Scarlett O’Hara
Name: Bridget
Baton Rouge, LA (Zone 9a)
C’est la vie .........
Berrycajun
Feb 9, 2020 1:12 PM CST
Dixie3rose said:Black spot is also a leaf spot disease that is best prevented. Forget about milk or baking soda being an effective control, studies show that below the upper parts of the US it doesn't work. Copper is somewhat effective, so are products with myclobutanil, which is a systemic fungicide, and combine it with Mancozeb, which is contact fungicide. If you spray Mancozeb three times, three days apart, spray ground and old leaf debris, and this will get black spot under control. Don't forget about contacting the American Rose Society [email protected], and look up a Consulting Rosarian for advice too. There was a new organic product I saw at a recent ARS national convention called Rose Shield. The company gave out free spray samples. Will try it and hope it works. I'm in the northeast side of South Carolina.


Interesting that the milk recipe won't work in the South. I have also since read that you have to spray it once a week throughout the entire growing season, which here is almost the entire year. So that's just not doable for me. My roses are spread throughout a half acre and most are climbers so I'd be spraying my life away.

I'm thinking I'll just leave it. I'm disappointed because i chose roses that are said to be good for my location. New Dawn, however, looks just awful. The others are doing ok though
After all, tomorrow is another day!
— Katie Scarlett O’Hara
[Last edited by Berrycajun - Feb 9, 2020 1:20 PM (+)]
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Name: Lynda Horn
Arkansas (Zone 7b)
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gardenfish
Feb 9, 2020 3:45 PM CST
Wow, had no idea that you had so many. For you, then maybe a systemic is the only solution. Pick carefully. Some previous poster talked about a new one. Because beneficials don't tend to hang around roses like they do other garden plants, this may be your best bet. I don't think that a systemic for the disease alone would do much harm to the beneficials. I use spray on my roses (copper), and I see mantids on the roses from time to time, doesn't seem to affect them. Anything you would use to combat black spot, even a systemic, would have to be applied on a regular basis, but a systemic has longer periods of time between applications. Remember, you are trying to control it because you can't eradicate it, thus the regular treatments.
“ Be kind whenever possible”
14th Dalai Lama
Minnesota (Zone 3b)
RpR
Feb 12, 2020 9:51 PM CST
Berrycajun said:
I'm thinking I'll just leave it. I'm disappointed because i chose roses that are said to be good for my location. New Dawn, however, looks just awful. The others are doing ok though


Diseased leaves on the ground ensure that your disease will never leave, and get worse.
I use a wet/dry vacuum when I do a serious ground clutter removal and douse heavily the soil, when I douse the roses.
I use Serenade and similar such products (Actinovate etc.) you could take a step ladder and douse even a climber unless it is a extremely tall.
In Minn. we can get hot-humid summers like yours and even then repeated application is the only way to not let it have its way, while not eradicating it.
One serious not is such things as Black-Spot may not kill but they weaken the rose for other ailments.
Name: Lynda Horn
Arkansas (Zone 7b)
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gardenfish
Feb 13, 2020 12:08 AM CST
@RpR, thanks for the Thumbs up on Actinovate, someone on the rose forum suggested using this... I tend to switch out fungicide every few years, they seem to quit working as well. Used copper the last two years, pretty good. I agree on the cleanliness part, absolutely essential to remove all the leaves from the ground and spray the ground. I will be cutting back this weekend and will do a complete removal of mulch underneath, a drench spray and replacement of mulch.
“ Be kind whenever possible”
14th Dalai Lama
Name: Kathy
Nocona,Tx zn.7 (Zone 7a)
My garden..my "Peaceful Haven"
FAIRYROSE
Feb 15, 2020 4:30 AM CST
I am so surprised your New Dawn has blackspot! Mine's been thru 4-5 flooding episodes(planted near the lake) and never shows any BS. I have a Grandmother's Hat that gets a "strange looking" BS every yr and recently saw this post on a FBook site..1st photo. You may want to read up on DOWNY MILDEW. It sure can resemble Blackspot!
Thumb of 2020-02-15/FAIRYROSE/7c07ae


Thumb of 2020-02-15/FAIRYROSE/b702d7


Thumb of 2020-02-15/FAIRYROSE/7677f6


Thumb of 2020-02-15/FAIRYROSE/833e8e

God's in his Heaven, all's right in my World
Name: Lynda Horn
Arkansas (Zone 7b)
Eat more tomatoes!
Lover of wildlife (Raccoon badge) Container Gardener Lilies Cat Lover Lover of wildlife (Black bear badge) Zinnias
Organic Gardener Heirlooms Bee Lover Hummingbirder Echinacea Tomato Heads
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gardenfish
Feb 15, 2020 8:08 AM CST
Well, blow me over with a feather! I think now that I have this! One would think that with that name, you would get a look similar to powdery mildew, which we get on zinnias here, and also phlox. I'm using copper, so I guess I'm on the fight track to control this, too. I really should send some of my rose leaves to the state extension office; I do this with my tomato diseases, so why not the roses?
“ Be kind whenever possible”
14th Dalai Lama

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