I have to laugh...I know Zuzu knows her roses, and being we were discussing the different opinions of removing dead leaves from the base of plants or not I will post this.
Speaking of black spot.
"When plants are badly infected, leaves drop prematurely and canes may become
completely defoliated, thereby reducing the quantity of the flowers and eventually killing the plant".

http://pods.dasnr.okstate.edu/...
No, I am not saying one is right or one is wrong, just another example of what we think we know, is not always what we thought we knew.

Seedfork said:A pretty bloom on a plant covered with black spot, or naked of leaves is just not for me, the foliage needs to be as pretty as the bloom. It's like a pretty girl with bad teeth, just takes the pazaz out of it for me.

I have to agree with you there. I like my rose shrubs green and healthy looking.

Larry,

I agree with you. I am guessing that you have far more disease pressure in Alabama than either Zuzu or I have in our California gardens in that we don't get any summer rains. Zuzu's garden is more likely to have bs than mine as her garden is more coastal than mine.

I have removed the roses that defoliate in our wet spring and do not get new foliage in time to get through the high temps I have during the summer months. There are plenty of roses I can grow without that problem.

For me to be happy, I need to have a healthy plant. Not only that, but a healthy plant has a better immune system and can fight off disease. Like Zuzu, some of my roses can get bs in a wet spring, but after the heat hits, I don't have any problems. I can tolerate some disease during that period as long as the plant is clean for the rest of the season.

Time management in my garden is a big issue for me because I have to garden on five different levels, so if there is any task that is unnecessary for plant health, even tho' it is recommended on several sites, I am going to skip it.

I started mulching twice a year in the beginning simply to build my soil. Finding out that this cultural garden task inhibits pathogens was a bonus.

A lot of what you see, even on the university sites is distorted information because there is no way they can compensate for all of the variables in our gardens when they create a study. No university can test for all of those variables, climate (humid vs arid), heat tolerance, cold tolerance, type of soil, alkalinity or acidity of the water used and more.

All of the variables I mentioned above and the "more" impact the health of a plant.

Any plant disease, insect infestation or lack of water and improper watering of plants that causes a rose to defoliate will kill the rose. So the quote above could apply to a severe spider mite infestation, saw fly infestation, grass hopper infestation, mildew infestation, drought, etc.

Smiles,
Lyn

Well said!

Very interesting posts and informative links from everyone,..where i live we have at least 200 days of rain in a year and so black spot is sure to appear despite this i constantly fight it off and most years i win,..Liquid Soap and Neem Oil,..Mixture of milk and Water,..baking Soda and Water,..except for the Neem Oil everything else is found in use in the house,..its just that i hate buying store made sprays,..costly and don't always work,..i am always on the look out for a leaf with Black Spot and will remove it and burn it then wash my hands after handling the leaf before venturing into the garden again,..old habits die hard lol,..alas the battle against unsightly black spot goes onward,..unless i change to disease resistant rose bushes,..too late i fear as my present roses have grown on me.

RoseBlush1 said:Any plant disease, insect infestation or lack of water and improper watering of plants that causes a rose to defoliate will kill the rose. So the quote above could apply to a severe spider mite infestation, saw fly infestation, grass hopper infestation, mildew infestation, drought, etc.

While I agree that a lack of water can kill a rose, and I've never had spider mites or grasshoppers in my garden, my roses have been defoliated by black spot and sawfly infestations year after year for decades, but they're still alive and healthy, some for 30 years now. Maybe because the defoliation doesn't last long. The absent leaves are quickly replaced by new growth.

As for mildew, my Dorothy Perkins roses were defoliated by powdery mildew for years before I dug them up -- not because they were dying, but because they were so vigorous that they threatened to eat my house.

zuzu said:

While I agree that a lack of water can kill a rose, and I've never had spider mites or grasshoppers in my garden, my roses have been defoliated by black spot and sawfly infestations year after year for decades, but they're still alive and healthy, some for 30 years now. Maybe because the defoliation doesn't last long. The absent leaves are quickly replaced by new growth.

As for mildew, my Dorothy Perkins roses were defoliated by powdery mildew for years before I dug them up -- not because they were dying, but because they were so vigorous that they threatened to eat my house.

Zuzu .... you live in a rose-friendly climate, which is not universal, so your experience in your garden is not universal. When I lived in San Diego, I thought I was living in rose heaven because I never had the extreme issues many people in other climates had to deal with while caring for their roses.

What I was saying is that whether the defoliation is caused by disease and/or insects, it impairs the function of the plant. If conditions are more extreme than what you experience in your garden, the survival of the rose is at risk. It takes longer and more work on the gardener's part to save the rose.

Up here, my day temps can be in the 70s and jump to the high 90s or low 100s in a couple of days and stay there for the rest of the summer. If I have a rose that has defoliated for any reason and the temps are at 100F, I have to take special measures to save the rose. Yes, I know what to do, but it's still extra work. It also takes longer for the plant to re-foliate because of those extremes. If this happens on a regular basis, it eventually weakens the plant and it doesn't survive the next crisis.

I do get spider mites because the conditions are right for them to thrive ... hot and dry. Again, I know how to save the rose and stop the infestation from spreading to other roses, but if I did nothing, the rose would die. With no foliage to pull sap up the canes, the rose cannot produce the new leaves it needs for photosynthesis.

In other, more humid climates through out the growing season than yours, the disease pressure is higher and impairs the functionality of the whole plant more than it does in your garden.

I have seen roses killed by mildew because they did not have any functioning leaves. Some roses, like Dorothy Perkins, in the right conditions, can come back from that kind of plant disease. Other roses can outgrow the propensity to mildew and once they are no longer juvenile plants, will take off and never look back and be wonderful roses. It depends on the rose.

There is no one perfect answer when you look at only one garden with one set of conditions. There are many other variables at play, too. The reason you can still grow healthy roses in spite of the diseases and insects that are a real problem in other areas of the country is because your climate and garden conditions give you more room to ignore the problems I've mentioned in my post.

Also, you are willing to ignore bs infected plants because you are in love with the blooms ... nothing wrong with that, but not every gardener looks at gardening that way. I happen to be a foliage junky. I love seeing the different foliage play off of each other as much as I love the blooms.

I want healthy plants not only for how they look in the garden, but because, for me, they are less work to take care of on a long term basis.

Lyn

RoseBlush1 said:Sue ...

We have a horticultural representative from UC Davis up here and I discussed this with her last year and she confirmed that spores cannot live on dead leaves.

But, to re-quote what I quoted above "Conidia lose viability rapidly, few surviving more than one month. Overwintering is by saprophytic mycelium in cast foliage or infected stem tissues" (Conidia are a type of spore). That actually agrees that the spores don't last long, but on the other hand says the fungus overwinters as mycelium in fallen foliage or stems.

Quoting another source, Diseases of Roses and their Management, University of Florida, 2011 "The fungus overwinters as mycelia in fallen leaves or in infected canes that may produce new acervuli or apothecia in which conidia and ascospores form each spring. "

Thus it appears to be the fungal strands themselves that overwinter on fallen leaves (and canes), and then produce new spores in spring. Pathogenic fungi often have more than one way to survive, just because the spores don't survive very long doesn't necessarily mean that it doesn't have another mechanism by which to winter over. In this case it appears to be as mycelium (fungal threads).

Interestingly, it was UCDavis authors who wrote the American Phytopathological Society article on black spot I also quoted that said "Remove fallen leaves and other infested material and prune out infected stems during the dormant season". This indicates copyright 2015. UCDavis's own website, in their 2009 revision of how to manage pests, roses, blackspot, says, under Survival of pathogen and effect of environment: "On living and dead leaves, and on infected stems. Waterborne spores are spread by splashing water."

Given that sanitation is such an important part of IPM, even if it just reduced or delayed the disease it may still be worthwhile removing fallen leaves. I don't think anyone is suggesting it's going to get rid of black spot entirely since it can winter over on canes too.

RoseBlush1 said:
Not all roses are susceptible to all of the five strains/races of bs in the United States. That's why a rose might be very disease prone in one climate and the same rose be totally clean in another climate. The bs race in the second climate is different than the one in the first garden. The second garden may have roses that are bs magnets, too, but it's a different race of bs.

Agreed, this situation isn't uncommon in plant diseases. Doesn't really help the ones that get it badly here, though, and which are obviously susceptible to whatever strain/s occur locally In a bad year they defoliate and don't have enough time to regrow leaves before winter.

"The black spot fungus overwinters in fallen leaves and in lesions on infected canes. White, slimy masses
of microscopic spores (conidia) produced in diseased tissue are splashed by water or wind-blown rain
from fallen leaves and cane lesions to the opening leaves in the spring......."

"Conidia lose viability rapidly, few surviving more than one month. Overwintering is by saprophytic mycelium in cast foliage or infected stem tissues" (Conidia are a type of spore)

Now these two statements contradict each other, not saying that really matters in the long run, it just shows science is not always...science.

Back to the original question from @rmbryant38: @Newyorkrita has a system of prevention that clearly works for her. We have all seen her lovely, healthy roses. Perhaps our new member would like to give it a try. I am sure we have all confused the issue beyond all expectations.

porkpal,
Well it seems we all forgot our manners and none of us even welcomed rmbryant38

I guess black spot is an important issue to us all and we got carried away. The original question was "What is the best spray for black spot".
dyzzypyxxy, gave some suggestions and I stated that I had not much luck with sprays. It is a hard question to answer, I guess in some areas black spot is worse than others and I suppose the selection of roses would influence that also. In his/her area the organic methods might do just fine and they may have no need for chemical controls. I have used Daconil and Immunox but with less than satisfactory results.
http://www.walterreeves.com/la...

Seedfork said:
Now these two statements contradict each other, not saying that really matters in the long run, it just shows science is not always...science.

Actually, they don't contradict, what it means is that the fungus overwinters as mycelium (threads of fungus) in fallen leaves (and lesions on canes). Then in the spring this overwintered mycelium produces a new series of spores that splash onto new leaves re-starting the infection cycle. The mycelium is the actual body of the fungus, the spores are the reproductive units it produces. They're not saying that spores survive the winter.

porkpal said:Back to the original question from @rmbryant38: @Newyorkrita has a system of prevention that clearly works for her. We have all seen her lovely, healthy roses. Perhaps our new member would like to give it a try. I am sure we have all confused the issue beyond all expectations.

My regiment is spraying every two weeks with systemic fungicide. Never miss spraying. It is a lot of works but it is extremely effective!

White, slimy masses of microscopic spores (conidia) produced in diseased tissue are splashed by water or wind-blown rain from fallen leaves and cane lesions to the opening leaves in the spring......."

"Conidia lose viability rapidly, few surviving more than one month. Overwintering is by saprophytic mycelium in cast foliage or infected stem tissues"

Not sure what they "meant", but I know what they say. The first sentence states that conidia over winters and transfers to the new leaves in the spring, the second sentence says conidia lose viability rapidly few surviving more than one month. So either one or the other is incorrect it looks like to me. I will leave the meaning up to each reader to decide.

Seedfork said:White, slimy masses of microscopic spores (conidia) produced in diseased tissue are splashed by water or wind-blown rain from fallen leaves and cane lesions to the opening leaves in the spring......."

"Conidia lose viability rapidly, few surviving more than one month. Overwintering is by saprophytic mycelium in cast foliage or infected stem tissues"

Not sure what they "meant", but I know what they say. The first sentence states that conidia over winters and transfers to the new leaves in the spring, the second sentence says conidia lose viability rapidly few surviving more than one month. So either one or the other is incorrect it looks like to me. I will leave the meaning up to each reader to decide.

I don't see where in the first sentence it says that conidia overwinter?? It says they are splashed to new leaves in spring but doesn't say they've been there all winter. The article you're quoting is this:
http://web.aces.uiuc.edu/vista...

If you read further down that same article, it says "Following defoliation in the autumn, the hyphae go deeper into the dead leaf tissue and form black specks (pycnidia) under the old acervuli. The pycnidia rupture in the spring, exposing the white slimy masses of conidia and completing the disease cycle.."

No, your right, it does not say where those leaves came from..I just assumed they had to be talking about the ones left over from last winter. Where did those darn things come from?

Sue ...

I have no need to have the right answer here, I was just passing along information from people I trust, but haven't done any research myself. I'd probably get more intense about it, if bs was more of an issue in my garden.

One of the reasons I love reading the Rose Hybridizers Association forum is that I love reading the discussions between people who know a whole lot more about roses than I do and who have a far deeper scientific knowledge of plants than I do.

I've never experienced the kind of winter you have in Canada, so what I define as winter is different than what you think of as winter.

As what is best to spray to control bs, I wouldn't have a clue as I have a no spray garden. I just remove the roses that don't make me happy.

To be honest, if I did have to spray the whole garden (I have over 100 roses), I probably would not grow roses as much as I love them. That's me. I am not telling anyone not to spray. I can't keep up with the garden chores I have now without adding another task ...

Lyn

Seedfork said:No, your right, it does not say where those leaves came from..I just assumed they had to be talking about the ones left over from last winter. Where did those darn things come from?

They're the leaves you didn't clean up in the fall, Larry What they're saying is infected leaf falls to ground, spores gradually die, sooner rather than later. Fungal body lives on in dead leaf which continues to lie there over the winter. In spring the fungus comes to life again and releases fresh spores to re-start the cycle.

RoseBlush1 said:I have no need to have the right answer here, I was just passing along information from people I trust, but haven't done any research myself.

I understand that Lyn, and wasn't trying just to be right or for the sake of being argumentative. The thing is this was originally posted in Ask a Question before it was moved to "Roses" and we were trying to give advice. Whether it's of value to clean up dead leaves is totally relevant to control methods for diseases and there were two differing opinions stated. Others may have a need, or desire, to have the right answer and if something had changed I too wanted to know.

RoseBlush1 said:I've never experienced the kind of winter you have in Canada, so what I define as winter is different than what you think of as winter.

Actually I'm originally from the UK so I have experienced wicked winters like the one we just had here this time around, and also a climate where we could have roses in flower at Christmas.

I'm quite happy to let go of this subject, if people haven't made up their minds one way or another by now they're probably not going to