Roses forum→Mulch and diseases ?

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Name: B C
NY (Zone 5b)
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BrendanCS
Jun 30, 2020 5:37 AM CST
We've had about 3-4 days of rain and high humidity 80-90s% day and night after a spring of little rain and a lot of hand watering in my zone 5. I've noticed that about half of the roses have developed powdery mildew and a few leaves of blackspot after all this rain and humidity and wonder if the mulch I added to the top of the soil may be impacting the plants.

Was reading up about how some mulches may lead to more fungal problems, but can't seem to find a unanimous answer. When I first planted, I covered around each bed with compost and mulch that a local landscaper friend recommended to get in bulk.

The compost is "Leaf compost, small amount of limbs and brush. Screened and windrowed for 8 months to 1.5 years. No manure."
and then an inch of mulch on top of that which I kept about 6-8 inches away from the center base of each rose:
The mulch: "100% bark, mostly hardwood, ground and broken down"

The mulch and compost layer stay pretty moist unless we have a couple of days of extreme dry heat like we did for May and the beginning of June. About a week or two ago before the rains started, I also noticed lots of little off-white mushrooms growing in the mulch.

Each plant is a bit low to the ground level of compost/mulch because I am new to this and adding the compost and mulch around them created a slight sink-hole to each after planting each so deep. The leaves yellowed at the very bottom on most of these early on but I've been doing my best to clean any fallen petals and leaves around each plant each day. Turning out to be a full time job, which I don't mind at all, I love plants. But I'm hoping I didn't mess up with the mulching or something else.

If you think it might be best, I can softly pull back the mulch I added and leave just the compost or add a better mulch. My local nursery where I got the compost and mulch sells other mulches in bags which I don't mind purchasing like these:
Coast Of Maine Dark Enriching Mulch
Coast of Maine Lobster Compost with Spaghnum Peat Moss
Coast of Maine Cow Manure Compost with Spaghnum Peat Moss
Master Nursery Bumper Crop Organic Soil Builder
and Jolly Gardener Pine Mulch
Would any of these be better to put around the roses to help fight fungal disease?

Also last question...is it normal for the stems to turn yellow/oramge right where I deadhead? I've noticed this on a few of my plants...I'll deadhead about a half an inch under the bud and a couple of days layer the small bit of stem left there before the next leaves usually yellows? In the last picture with the mildew, you can see it on the very top right.

Thanks you for any tips, hopefully they'll spring back with their green leaves and healthy growth.

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Name: seil
St Clair Shores, MI (Zone 6a)
Roses Garden Photography Region: Michigan
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seilMI
Jun 30, 2020 6:54 AM CST
I would say those roses look pretty darn happy and healthy!! Roses will often shed a few leaves here and there. They're usually older, inner or bottom leaves that are no longer producing enough food to earn their keep so the rose lets them yellow and die off. That's very normal.

I think your compost and mulch is fine and is not the culprit causing the powdery mildew and black spot. The weather is. In rainy or high humidity PM and BS thrives! The mushrooms appearing in the mulch attest to how damp things are for you right now. There isn't anything you can do about the weather and the only thing you can do about the PM & BS is to spray if it is that bad or bothers you that much. I'm a non-sprayer so I just live with the spots. When things dry up they usually disappear.

Don't worry about the little wells around the roses. As the mulch and compost decay those will level out anyway. Adding any kind of top dressing will create that affect.

Yes, that little die back on the flower stems after dead heading is completely normal and nothing to worry about. If you don't like the look just snip them off or just dead head to the first leaf set. The usual rule of thumb is to go to the first 5 leaflet but a lot of people do what you do and just snip off the spent bloom right below the hip. Either way is fine.
Name: Mike Stewart
Lower Hudson Valley, New York (Zone 6b)
I was one of the first 300 contributors to the plant database! Photo Contest Winner 2020 Garden Photography Roses Bulbs Peonies
Lover of wildlife (Black bear badge) Dog Lover Cat Lover Birds Enjoys or suffers cold winters Region: New York
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Mike
Jun 30, 2020 2:24 PM CST
I'm so glad Seil answered before I did because now I don't have to take the time to carefully say everything she said so well. Her analysis is spot on.

Edited to add: Is that Golden Celebration you're growing? If so, it looks really good.
[Last edited by Mike - Jun 30, 2020 2:26 PM (+)]
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Name: B C
NY (Zone 5b)
Image
BrendanCS
Jun 30, 2020 3:20 PM CST
Seil: Thanks so much for your detailed answer, I really appreciate it! I'm completely new to roses. Always just kept my focus on my rare succulent/cacti collection and then my perennial garden which has been basically a "dig a hole, transfer from pot, hopefully it grows". Roses were intimidating to me, but this year I caught the bug after snooping on forums and having too much time on my hands with the pandemic. They really are beautiful plants, and the flowers have so much more variety than I thought before. Nervous because I overdid it and bought about 40 for different areas of my yard and after digging all of those insane holes, I think about them too much now! I'll keep my eye on them and hopefully the weather changes Smiling I am trying to keep a chemical free garden, especially because of my dog. All of the bugs that took over the roses for a while tempted me....but I just spent time squishing them and spraying them with my hose.

Mike: Thanks! That is actually Crown Princess Margareta. Her flowers change a lot from salmons to oranges to golden yellows. I have no idea why, but I really love it. Out of all of these I've planted, she's growing the fastest so far this summer. Maybe doubled or tripled in size. No clue why, she's in a bed with a few other climbers which are growing too but no where near her speed. She won't seem to stop flowering either no matter how much I deadhead, but I love it. Also want to mention that I have been reading your post history in particular, because I saw that you also lived upstate, and wanted to see how roses do up here. I don't know any gardeners here (only lived here 4-5 years now), so I never thought roses would do well with our winters. After seeing your posts and photos, which man are they beautiful, I fell down this rose rabbit hole ha. Hopefully some day my roses will look half as exciting as yours Thumbs up
Name: B C
NY (Zone 5b)
Image
BrendanCS
Jun 30, 2020 3:26 PM CST
Here are some more pics her different colors so far...hopefully she'll survive winter:
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Name: Lee-Roy
Bilzen, Belgium (Zone 8a)
Irises Lilies Hostas Ferns Composter Region: Belgium
Lover of wildlife (Black bear badge) Region: Europe
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Arico
Jun 30, 2020 3:59 PM CST
Powdery mildew is usually an indication of very dry conditions so that's quite contradictory. Blackspot is common in damp weather also. Neither pose much problems to a healthy rose except the aesthetics.

Woody mulches don't lead to more fungal problems since the fungi that attack your plants (parasitic etc) are usually not the same ones that inhabit your mulch and soil (saprotrophic and mycorrhizal).
The latter ones are very beneficial as they are one of the few organisms that can recycle the woody material (lignin) and return those nutrients back to the soil in a form able to be taken up by plants. The mushrooms you see growing are merely the fruiting bodies for spore dispersion; the bulk of the fungus is invisible.
The mycorrhizal ones actually penetrate the root(s) (hairs) of your plants and invade either the intercellular space or intracellular space (inside the actual cell) or just wrap around the outer layer. Either way, they greatly increase the surface area of nutrient uptake (mainly phosphorous) which they trade with their host in return for hydrocarbons (sugars).

So it's better to mulch than not to mulch. Of the possible hundreds of thousands of fungi species, only a tiny minority are disease inducing.
Name: Mike Stewart
Lower Hudson Valley, New York (Zone 6b)
I was one of the first 300 contributors to the plant database! Photo Contest Winner 2020 Garden Photography Roses Bulbs Peonies
Lover of wildlife (Black bear badge) Dog Lover Cat Lover Birds Enjoys or suffers cold winters Region: New York
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Mike
Jun 30, 2020 6:22 PM CST
Brendan, welcome to the world of growing roses! I think you've gotten off to a very good start. if you want to see the roses I've grown in New York over the past 20 years, you can find them catalogued on this page of my photography website:
http://lens-work.com/public_ht...

Since I'm in zone 6b, and you are in zone 5b, there are some roses I grow that might be borderline or not quite hardy enough for your area further upstate. However, most of them would do fine in your neck of the woods. Still, if any of your roses are grafted onto rootstock instead of growing on their own roots, you might want to make sure the graft is buried a few inches below the soil surface. You might also want to give them winter mulch or pile loose soil around the base during their first year if they are grafted varieties.

I agree with Arico in that I usually associate powdery mildew with drier conditions, but I've come to learn that anything is possible in my rose garden, and powdery mildew sometimes shows up after a dry spell that has suddenly turned humid. However, my concern with fungus infections goes beyond their aesthetic impact. Although rose bushes can continue to bloom even after becoming nearly defoliated by particularly bad outbreaks of blackspot, it doesn't mean that they will thrive the way they would with healthy foliage -- for the simple reason that the loss of leaves inhibits the plant's ability to photosynthesize and produce energy. The loss of a few leaves is no big deal, but under the right conditions, blackspot can run through a rose garden like wild fire and defoliate a plant in just a few days.

That's why I use both a preventive spray to prevent black spot, as well as a contact fungicide to kill it on contact if it does manage to appear. I also alternate the sprays I use to avoid the problem of resistant strains developing in the garden.

Minnesota (Zone 3b)
RpR
Jun 30, 2020 6:52 PM CST
Douse the mulch with a bio-fungicide to help prevent the Black Spot or it will splash up from the ground.

By douse I mean gallons on the ground , I do this often , after, picking off the infected leaves and while I still deal with it on some plants, (I have had new plants that came with it already) and I do not have problem as long as I keep at it.
I use Serenade and Sonata most of the time along with Actinovate and Oxidate.
There are now some others in the same category as Serenade and Sonata so check online .
I buy 2.5 gallon jugs which is far cheaper in the long run.
This will also help with other nasties.
Name: Mike Stewart
Lower Hudson Valley, New York (Zone 6b)
I was one of the first 300 contributors to the plant database! Photo Contest Winner 2020 Garden Photography Roses Bulbs Peonies
Lover of wildlife (Black bear badge) Dog Lover Cat Lover Birds Enjoys or suffers cold winters Region: New York
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Mike
Jun 30, 2020 7:23 PM CST
RpR, why not just spray the leaves with a little bit of fungicide as a preventive than pouring gallons of fungicide into the ground?
Name: Porkpal
Richmond, TX
Charter ATP Member Dog Lover Cat Lover Keeper of Poultry Keeps Horses I was one of the first 300 contributors to the plant database!
Garden Ideas: Level 2 Plant Identifier Raises cows Roses Farmer Celebrating Gardening: 2015
porkpal
Jun 30, 2020 8:37 PM CST
Aren't some fungi beneficial to the soil?
Porkpal
Name: Mike Stewart
Lower Hudson Valley, New York (Zone 6b)
I was one of the first 300 contributors to the plant database! Photo Contest Winner 2020 Garden Photography Roses Bulbs Peonies
Lover of wildlife (Black bear badge) Dog Lover Cat Lover Birds Enjoys or suffers cold winters Region: New York
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Mike
Jun 30, 2020 8:44 PM CST
Absolutely!
Minnesota (Zone 3b)
RpR
Jun 30, 2020 9:38 PM CST
Mike said:RpR, why not just spray the leaves with a little bit of fungicide as a preventive than pouring gallons of fungicide into the ground?

Black Spot is in the debris on the ground, heavy rain it splashes back up on the plant and if you do not do some thing to remove it (including removing all debris on the ground , if possible, it will be there year, after year, after year , after year, after year....

I blow away the remaining leaf debris that I use to cover my roses every year, and usually douse the plants in spring before I add Cocoa Bean hulls for mulch then if I see, start, I pick the leaves off and douse the soil again along with treating the plants.
Cocoa Bean hulls, two to three inches deep, keep the ground from splashing up but some times BS come out of now where probably the wind or as I said, I have had newly purchased plants that bring it with them.
If you read my post in Norther Gardens about the now all but extinct Munsinger Rose Garden in Minn., you can see what Black Spot unchecked, along with not dealing with the ground they grow in, can do to a very large garden.

I did not put it in that post but two years ago I was there and spoke to a gent working there about the Black Spot that was running rampant and he said the lady in charge would not allow them to use ANY sort of commercial disease control on the roses.
[Last edited by RpR - Jun 30, 2020 9:46 PM (+)]
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Name: B C
NY (Zone 5b)
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BrendanCS
Jul 1, 2020 7:36 AM CST
@Arico - Thanks for all the info. I figured mushrooms and fungus growing was a good thing...but after trying to read through as much info on blackspot and mildew on roses, I started to get confused with mulch/fungi/decomposing and every different article about it all. What you said makes perfect sense, kind of like a forest that's completely alive from the ground up. I like the look of the mushrooms too.

Do you happen to know anything about slime mold fungus? In one particular area I've been getting patches of it on my mulch. My partner has little interest in it since it looks a bit like vomit, but I'm a painter/sculptor and actually think they're kind of beautiful. I've been shoveling it up and tossing it in the mornings though because I'm not sure how beneficial it is.

@Mike - Beautiful website and photographs. Your gardens look great, very inspiring. Some day I hope to have some really nice walls of roses and also get some perennials and native plants mixed in with them. I love your close ups too....you now have me hooked on the variegated looking roses with the stripes! That orange/yellow combo in particular is really standout. Your husky is equally beautiful. Also love your mushroom photos...I do some photography/sculpture too with resins/molds and the shapes/colors of all those mushrooms are really great. Time for a trip to Bear Mountain.

Great to know about mulching and winter protection. I buried all of my roses about 4-6 inches below ground level when I planted after reading about it. Took a lot of work to dig and get them that deep...and of course, afterwards I spent a week wondering how it was even possible that this was a good way to plant something without it rotting hah. I'm so used to worrying about all of my succulents and cacti rotting that these new roses are still throwing me off. Burying deep and so much water. I have no idea if mine are grafted, but I assume so. The majority of the 40 I got are David Austins...from a local nursery. There are some others I found too, New Dawn, Colette, Cream Veranda (might be dead...for some reason after the Rose RX it seems to have given up). But I assume they're grafted since their crowns/center areas kind of looked that way when I was planting them.

Do you have any recommendations on anti-fungal sprays you mentioned? I know I have Bayer Disease control for roses/shrubs in the garage somewhere....but besides that I only have this other spray I bought when I got my first batch of roses....Rose RX. The person at the nursery told me it wasn't poisonous to my dog so I figured I'd give it a shot. When the first powdery mildew showed up on a few of them in April...I sprayed them at dusk. Next day their leaves fried, and they're still kind of recovering. Would be great to get some advice on some other fungal sprays that aren't as harsh on the plants. I get blazing full sun here. I'm at a high point in Rhinebeck and my yard is nonstop sun (great for the roses and other plants, not for me around 1pm).

Thanks again for the help everyone, really appreciate it. Here are some pictures of my Bathsheba changing colors


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Minnesota (Zone 3b)
RpR
Jul 1, 2020 12:08 PM CST
Unless you have an insect problem I would stay away from the X in 1 type treatments.
I use Serenade , Sonata and several other bio-fungicides, they go not kill good stuff in the ground.
Do a net search on bio-fungicides for roses but do not go by what the first site you come to says, check a bunch if for no other reason than to see what is out there.
Buy in bulk.

Where I am -20 F in winter is norm so I have been burying, tipping and totally burying, then covering with several feet of leaves, my roses for years.
I have just put in new roses and I will not do that again till the roots are well established but I did find out the hard way, when I did not treat, with a fungicide, a very large rose well enough one year , the very large canes got infected and two years later it was dead.
I have nearly entirely Hybrid Tea which are fussy but it is best to prepare for the worst.
Name: Lee-Roy
Bilzen, Belgium (Zone 8a)
Irises Lilies Hostas Ferns Composter Region: Belgium
Lover of wildlife (Black bear badge) Region: Europe
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Arico
Jul 1, 2020 3:22 PM CST
BrendanCS said:@Arico

Do you happen to know anything about slime mold fungus? In one particular area I've been getting patches of it on my mulch. My partner has little interest in it since it looks a bit like vomit, but I'm a painter/sculptor and actually think they're kind of beautiful. I've been shoveling it up and tossing it in the mornings though because I'm not sure how beneficial it is.



Slime moulds are not really fungi although they are named that way and formerly were included in the fungal kingdom; but they are now part of the protista (don't try asking about the details because that's too complicated Hilarious! )
They are a congregation of otherwise free living single celled organisms (of the same species). They feed on dead organic matter or microscopic life (bacteria, protozoa, fungi etc) and I've yet to hear of them eating plants.

https://ucmp.berkeley.edu/prot...
Name: seil
St Clair Shores, MI (Zone 6a)
Roses Garden Photography Region: Michigan
Image
seilMI
Jul 1, 2020 8:04 PM CST
Thank you for the kind words, Mike!

Brendan, my best advice to you is, relax! Stop worrying and fussing so much and spend more time just enjoying your roses and garden. Roses are amazing survivors! Really. You have to work at killing them. I know, I've tried! Even fussy old HTs. People have been told for years and years how hard roses are to grow and it just ain't true! There are thousands of roses growing, all over the world, in abandoned places, with no care what so ever, that are still thriving! Their needs are very basic and the same as all the other perennials in your garden. They want healthy soil, the right amount of sunlight, lots of water, a good pruning once a year and, maybe, a little fertilizer once in a while. After that everything else is just gravy. Stop and smell your roses!
Name: B C
NY (Zone 5b)
Image
BrendanCS
Jul 2, 2020 5:00 AM CST
@Rpr - thanks for the info, I'll look into those two products and try to read up on bio-fungicides too.

@Arico - Good to know! I attached a picture of one I found one morning a couple days ago...I added new wood based compost and then wood mulch around the roses. After all the rain this past week it's probably perfect conditions for these strange molds. I wonder if I left them, if they would have any beneficial impact on the garden?

@seilMI - Thanks for this advice Thumbs up Perfect reminder that even my indoor collection did best when I stopped worrying about them so much. I remember a little over a year ago I had to spend more time in the city for work, so I wasn't at my place here upstate as much. After babying my indoor collection for the first years with humidifiers, heat lamps, heat mats and who knows what else, I just ended up putting my flourescent lights on a timer for them and watered whenever I was back upstate every two weeks or so. No more fussing, and the plants have never been happier hah. Great point about roses growing at abandoned places and surviving neglect. Every time I see a gigantic rose bush along the road I'll remind myself that there probably isn't someone tending to them every day and trying to fix the "mulch" or ph underneath them Smiling

Here is some of the beautifully ugly slime mold growing in one area of the garden. Took the pic last night when it started changing colors. Got nervous and shoveled into a garbage bag Hilarious!

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