Hi folks, Please help me with this. Don't know what it is or what to do. Thanks
It's probably any one of a few fungal infections but I'm not sure which. Find some Bayer Disease Control and spray with that. Do not use the all in one sprays. You don't need the other stuff that's in it. Look for just the disease fungicide.
Hi Psk8er: Seil is right, it's black spot. I have zero blackspots with the roses in the ground, mulched with alkaline horse manure (pH over 7.4). However, I get disgusting blackspots in the roses in the pot, mulched with alfalfa meal (pH acidic 5.8).
When the pH is neutral to slightly acidic, fungal germination is max. When the pH is alkaline, much less fungal. That's why acidic stuff like lemon rinds are NOT recommended for compost bin, since it breeds fungi.
My tap water is alkaline above pH 8. I let it sit there for years in the basement bottle with no fungi. But when I throw lemon rinds in, the pH goes down, and it breeds disgusting black fungi within days.
I induced BOTH blackspots and mildew on my roses by throwing acid fertilizer around them. My soil pH is very alkaline at 7.7 .... roses stay clean if I don't lower the surface pH. That's why baking soda spray is used for blackspots, and "Green cure" potassium bicarbonate (very alkaline) is used for mildew.
The key: keep the surface alkaline, and don't spread any sticky, slightly acidic alfalfa meal on the surface ... great stuff to breed fungi, and will splash up the leaves via rain water. Agriculture research used sulfate of potash (potassium to fight disease), plus MULCHING with lime pellets as beating using fungicide alone.
In my last house with acidic clay, and MULCHING with acidic pine bark, I had the WOSRT BS! Now with alkaline clay soil (limestone), I don't spray, zero BS if mulched with alkaline horse manure (dries faster than soil).
It's good to test the pH of your soil surface, to see if it's acidic. I wrote the below procedure, see the link:
Here is a link that might be useful: Cheapest way to test soil pH using red cabbage
Hold on. What is the name of the variety? Where in the country do you live? Is this just on one leaf? Did the leaf come from the bottom of the plant? Any other symptoms? Do you have a clearer photo?
Thank you Strawberry Hill... I went yesterday to buy alfalfa meal to make "tea" for them but they didn't have it. I can scratch that off the list now. I am in Alabama and boy do we have clay. All of them are mulched with pine bark. Last year the black spot was so bad some of my plants were almost defoliated. Looks like I have created the perfect black spot storm. I have sprayed every week with the Bayer Disease Control since I saw the first leaf but I guess it could be much worse if I hadn't. Your answer has me excited and thinking I might be able to beat it after all. I will test the PH and I suppose I should remove all mulch. Where do you get your horse manure? We haven't had horses in stalls for years but I do have several large piles of manure that we pushed out with the bobcat. They have been sitting there a long time but could I use that? It just looks like dirt now. I want to leave work and go home and get started! Thank you
Blackspot isn't inescapable. You can reduce your need for sprays (Bayer Disease Control has some significant environmental concerns) by selecting roses with maximum natural disease-resistance.
To do that, you will need help from gardeners in your local area.
Check the Internet for a local rose society, or even a local gardening club, to find folks that know your conditions. At the very least, visit one or more public rose gardens, and take note of which varieties are "clean," and which are not.
You will always have maximum success if you find roses that grow well where YOU are, and stick to those.
Hi Diane nj, I believe that leaf came from Pumpkin Patch but several of the bushes have it. I am in Alabama and it did not come from the bottom. I took this picture this morning and it is better. I live where internet and cell phone access is terrible so I can only answer when I am at work. Thanks
Looks like I have created the perfect black spot storm.
It's not you. It's your climate.
I would not remove the mulch. Mulch cools the soil (which roses like), and holds in moisture (roses like even moisture) and as it breaks down creates better soil--especially good for clay. The broken-down organic matter puts nutrients back into the soil and creates a looser texture. The bacteria and fungus that live in soil break down the material. This microherd works with plant roots for mutual benefit. All you have to do is keep the mulch at least a few inches away from the base of the rose, so the base gets fresh air and is not overly constantly wet.
Thanks Jeri, I will check into a rose society. I freely admit I don't know what I'm doing, I just love trying. The first thing I do in the morning and when I get home from work is walk through my roses and see what has happened since my last visit. I even go out during the winter and remind them better times are coming. I got the bug late but I got it bad. I am very thankful to have found a board where the members really help one another. You would be surprised at the number that only chat among themselves and ignore new members and requests for help. Thank you all!
Thanks. It does happen that the fist few leaves might have the disease depending on when you started your spray program. When you apply the Bayer fungicide, make sure to cover the leaf and the canes, and that you are applying as per the concentration listed on the bottle. There are some varieties that will always show some disease no matter what you do.
I agree with Jeri, contact a rose society close to you. Although I also live in a blackspot-heavy part of the country, I am not in your area, and they would be able to provide better, localized advice on care, extraordinary conditions, and disease resistant varieties. Good luck, keep us posted.
Horse manure is not going to control blackspot in Alabama.
Bayer Disease Control for Roses, Flowers, and Shrubs will control it if sprayed just every two weeks. Control doesn't mean you never see a spot, rather it means that you have no significant damage. Also, some of the leaves that were infected when you started spraying will have lived and still shown spots although the fungal body is dead. Frankly I don't think you need to worry.
Because the focus is still not quite sharp, I can't tell whether it is blackspot or some other fungus. The upper photo does not look like blackspot. The lower might or might not be it. Blackspot spots usually have vague or fringy borders. Look closely and see whether you see that.
No-spray rose gardeners in the Deep South usually go in for the old tea and china roses. Increasingly there are some modern roses that will do OK, but you need input from your own region.
Jeri, is right on the money. Make sure have a soil test done, that will help a lot. The reason I say this is the condition of your soil can make a big difference. A friend who has way more roses then me and has a no spray garden. Since we both live in BS country, we both have have it but her is barely noticeable. She believes in keeping the soil in her garden healthy.
I on the other hand, aim for control.. I use two different fungicides which I switch out monthly. This was suggested to me by a local member of the rose society.
Hi Psk8er: Horse manure is high in potassium, necessary to find diseases. EarthCo., soil-testing company, stated that 1/3 of soil is tested deficient in potassium. Jerijen and Kittymoonbeam reported using horse manure to suppress mildew in CA.
I agree with Michaelg that it depends on your region. My zone 5a has hot & humid summer with 40" of rain, plus 23" of snow. Cantigny rose park, 15 minutes away, with 1,200 roses use zero mulch, just bare dirt. If you google "shotgun fungus", you will see how spores are germinated in wet wood mulch.
Mulch is necessary in dry California, but a nuisance in my rainy & humid summer. My village has a huge pile of free mulch within distance but I don't use that stuff. It bred various icky-mushrooms that gross me out.
It's good to test the pH of the horse manure you get to see if it's alkaline, above 7.4 is great !! That means lime is added to deodorize. Lime is a fungicide. If you can find a bag of lime pellets to mulch your roses, it would be great! Check this out:
"Lime is calcium oxide. When lime reacts with water, calcium hydroxide or slaked lime results ... Calcium hydroxide is an additive in fungicides and in anti-mildew and anti-microbial formulas; it is designed to neutralize the acids in those solutions, forming a long-lasting fungicide. http://www.livestrong.com/article/122557-uses-calcium-hydroxide/#ixzz1znOdD1g5."
Below is the link to EarthCo. for a $20 soil test. You mail them 1 cup of soil (pre-paid by them), they e-mail you within a week as to your pH level, potassium, phosphorus, calcium, and magnesium.
You can get potassium through horse manure of sulfate of potash. Potassium is vital to fight diseases.
Below research explains why alkalinity suppress fungal growth, and neutral to slightly acidic WET mulch, or slightly acidic sticky alfalfa meal is great for breeding fungi:
Contrasting Soil pH Effects on Fungal and Bacterial Growth ��" 1 by Department of Microbial Ecology, Lund University, Sweden . 2. Soil Science Department, Rothamsted Research, United Kingdom. ABSTRACT
The influence of pH on the two principal decomposer groups in soil, fungi and bacteria, was investigated …
The growth-based measurements revealed a fivefold decrease in bacterial growth and a fivefold increase in fungal growth with lower pH. Below pH 4.5 there was universal inhibition of all microbial variables."
Below picture is my roses taken in late fall, when we have constant week-long rain. They are mulched with horse manure ... Not a single speck of black spot. My soil pH is 7.7, and the horse manure pH is 7.4.
Here is a link that might be useful: EarthCo. soil test for $20
This post was edited by Strawberryhill on Fri, May 3, 13 at 15:03
Wow, how beautiful. I really want beautiful foliage as well as blooms. It has been quite a surprise to discover the foliage is the hard part. Thanks for the information and the link. I will send a sample out Monday.
Hi Psk8er: I'm glad you choose a soil test. It's worth it.
A soil test costs only $20 and will tell if your soil is deficient in potassium (necessary to fight diseases). I wish I had done that in my last house, 1/2 hour away, with acidic clay .... back then I wasted money spraying my roses, it didn't help with BS.
In my current garden I don't spray, I focus on giving what they need: potassium for the health of the plants, plus maintaining a healthy microbe balance with horse manure (plenty of bacteria to suppress the bad fungi).
Henry Kuska (retired chemistry professor) once posted a link on how microbes in horse manure suppress fungi. My minor is in chemistry & I took a microbiology class in college ... that didn't help. Experience in my last house with acidic clay & acidic pine mulch and rampant black spots was what taught me.
I have the rush order form printed and can't wait. I can't imagine not having to spray. That would be wonderful but even if I still need to do some spraying that's ok too. I couldn't find the Bayer Advanced Disease Control for Roses ,Flowers and Shrubs so I ordered it. It was really disheartening to think I was still going to have terrible black spot anyway. I will also try to control myself and buy plants that do well in this area instead of just buying whatever I want. I have ordered from several companies but the two plants that have the most problem are from a local nursery. It seems like they should sell varieties that do well here. Thanks again
Crumbs! I've used pine straw around my few roses for the last few years. I like it 'cause it keeps the ground cool and rose toes don't cook. I too, wasn't aware of the fungus issue. I also use it around my azaleas/rhodys. I know they like acidy soil. What I've read here suggests I should leave the ground bare around the roses. So, just water but no mulch?
Mulch also helps to prevent weeds and helps to prevent erosion, in addition to the benefits I previously listed. I don't buy the argument that it encourages foliar disease. One university site says that mulch
'reduces incidence of disease by protecting above-ground plant parts from splashes that carry soil-borne inoculum '
It can be a problem if you pile it too thickly and too close to the base of plants (the 'mulch volcano' phenomenon) but it has so many benefits, and it is nature's way--where in nature are fallen leaves and other plant litters raked up and disposed of?
Here is a link that might be useful: URI document on mulch benefits.
Hi Fireweed: with regard to your question, it's OK to use alkaline mulch that dries fast like horse manure on sawdust bedding .... People here use limestone pellets as mulch, or decorative stones. Stones don't decay and fungi won't germinate. Stones don't retain surface moisture either!
It's the slightly acidic mulch like pine bark which retains moisture long that encourage black spots to germinate. Conversely, horse manure on woodchips/sawdust dries out fast, alkaline, with lime which discourages fungal germination. Hard-wood mulch dries out faster than other types.
I have a bed where I dumped tons of leaves ... that bed stays wet and acidic in our humid & gloomy weather. Most roses get black spots in that bed, despite my pH 7.7 clay. Everything in there gets mildew, including the weeds. The only roses that are clean are the disease resistant like Knock-out, FlowerCarpet, and Kim's Lynnie.
Hoovb's climate of California is dry and warm, so organic stuff decomposes fast on top. My climate is just the opposite, so stuff on top stays wet and breed fungi, except for where I mulched with horse manure with lime, or where I put limestone pellets on top.
My pile of compost ON TOP reeks and breeds fungi in our rainy and cool spring ... they can't decompose so they sour. When the weather is dry and warm, that pile dries out and smells better.
Leaves start out as acidic, then as it decomposes it shifts to neutral, then becomes alkaline as very well decomposed. Predfern, Ph.D. in physical chemistry gave me the link to University of Illinois on how leaves become alkaline once completely decomposed.
Hoovb' hot, sunny and dry weather permits total decomposition on top. My wet, gloomy, and cool weather prevents that from happening, thus the leaves stay wet and acidic, perfect for fungi spores to germinate.
I lived in California before (San Jose) ... it's dry and sunny, and I never see a mushroom there. I see plenty of mushroom growing on mulch and on the lawn here in Chicagoland, with cool and constant rain in the fall.
It's from an English magazine that I first read about NOT using bark mulch (retains wetness longer), but use horse manure as mulch to prevent black spots. England is a rainy and cool climate, perfect for black spots.
Below is an excerpt about black spots: " As is true with most fungi, this fungus requires free water for infection to occur. The spores must be wet for at least 7 hours before they can germinate.
A temperature of 65°F is best for spore germination and the disease develops most rapidly at about 75°F. Temperatures of 85°F and above inhibit the spread of the disease."
Here is a link that might be useful: University of Maine on Black spot of Rose
This post was edited by Strawberryhill on Fri, May 3, 13 at 22:33
Psk8er, I feel a little uneasy offering advice since I'm not in Alabama and have a totally different climate from you. I can say though that this has been a pretty active spring, disease wise in my garden due to the cooler weather (it's normally above 90 by now). When the weather warms up, I don't usually have to worry about blackspot until it cools down again in late October because the heat burns off the disease. I think looking for cultivars that are more resistant to disease is a very good idea. You needn't worry about perfection, but rather find a good balance that you can live with.
Firewood, if pine straw is working for you, keep doing it. I've mulched with pine bark, chipped hardwoods, and now I'm using about a 50/50 mix of horse manure/wood shavings. They all seem to work, but since the manure/shavings are free, that's what I'll continue to use. It has really improved my sandy soil.
Thank you, Floridarose, for mentioning about pine straw. Previously I saw the word "straw" and I was stumped, since I don't know the pH of the yellow straw in blocks for Halloween.
However, I tested the pH of "pine straw" before. I took PINE NEEDLES from my white pine trees, and soaked them in red cabbage juice: it's neutral, versus acidic for PINE BARK.
There's a discussion in the soil forum that pine straw is neutral, rather than acidic. It doesn't acidify the soil like pine bark. Pine straw is great for mulching, since stays dry on top, last long, and suppress weeds well.
Let's consider how roses grow wild in nature. They don't grow on a pile of leaves like woodland perennials. They don't grow on tree bark like mushrooms on decayed logs.
Roses grow in the valley where there's sunshine and water. Animals eat the hips of roses, then poop the seeds out. Roses are best on manure.
In my last house with acidic clay, BS was so bad that half of the leaves were gone. It was costly & time-consuming to spray a dozen Hybrid Teas. So I quit roses altogether for 15 years. Now I have alkaline clay, with 52+ roses, and it's much easier without spraying.
2011 was when we had 49" of rain that summer. I bought $5 worth of corn grits from the feed store: a 5 lbs. bag that lasts forever. I grind the WHOLE-GRAIN corn into dust, then used a flour-duster to dust my roses. It was fast, cheap, and efficient.
It was effective, Golden Cel. had only 3 leaves of BS, didn't drop though. Wise Portia had only 2 leaves of mildew. These got shaded completely by my tall house in the fall .. drenched in 7-days of non-stop rain. Why dusting with cornmeal worked?
1) the pH of corn is most alkaline among organic materials. It's 7.7 for cooked corn, and higher for DRY corn. I tested the cornmeal in red cabbage juice, pH is 8. Best to us whole-grain corn dust, it's higher in pH.
2) People use baking soda spray, but it has a drawback: high in salt. Cornmeal doesn't have salt, and it hosts the harmless Trichoderma fungi, that suppress the pathogenic BS fungi.
I have 52+ roses, spraying would be costly. It was much faster, safer, and healthier for my roses with cornmeal dusting. Chemicals can upset the normal flora of the ecosystem. Chemicals can hurt the beneficial guys, while killing the bad guys.
If you google "Cornmeal for blackspot", you'll see my previous experiment. Even the impatients got blackspots that year, shown next to the clean roses dusted with cornmeal with 7-days of non-stop rain.
I posted the link that I wrote for the English Roses forum again, so people can test anything to see if it's neutral/acidic for BS germination.
This post was edited by Strawberryhill on Sat, May 4, 13 at 10:56
Blackspot does not come from the mulch or the soil. Fungal bodies overwinter on the canes. Spores are carried from the canes to the leaves by splashing rain and then from leaf to leaf. We may spread it from plant to plant when we handle foliage. Infected dead leaves on top of the mulch can also carry the disease over the winter, but if canes overwinter, they are the main source. Applying a fresh layer of mulch in spring can nearly eliminate fallen leaves as a source. (Above info is from Horst, _Compendium of Rose Diseases_ and other science based sources.)
I have not seen any science-based writing that suggests the type of mulch or the pH of mulch has any effect on blackspot of rose. Mulching with horse manure was the standard way of fertilizing roses for centuries, so there is a long track record. My father did that in our yard in Florida, and he had to spray for blackspot.
The state of Alabama, like most states, provides low-cost soil testing through the land-grant university. Look under the county listings for "cooperative extension service."
It's the decayed OLD mulch, becomes wet & acidic that breeds black spots. When I researched into "artillery fungus", it's recommended that fresh mulch be applied yearly. Fresh & dry mulch from bags is best.
Once year I order a big pile of $$$ double-grinded fluffy mulch. In our wet spring, my neighbor complained that it stank up like fermented corn husk in silos. Anything fermented becomes slightly acidic, great for fungal germination.
One person in HMF commented that dusting with whole-grain corn meal was effective for mildew, but didn't work for her black spot. If the surface of the soil is acidic, be it soil, alfalfa meal, or mulch - the fungal spores germinate best, and get splashed up by wind or rain.
Even if you dust all the leaves & canes with corn meal at pH 8 ... if the ground is an acidic breeding wet pool of fungi, it defeats the purpose. Google "pictures of artillery fungus", you'll see black spots on white vinyl sidings.
Check out the below excerpt on "artillery fungus":
"Q: I have seen some spots on my car. Does the artillery fungus also get on cars?
A: Yes, this is common on the sides of automobiles when cars are parked near mulched areas that are infested with the artillery fungus. It is especially noticeable on white sports cars ��" In fact, we have had complaints where private companies have artillery spores on 50-100 cars in their parking lots.
Q: So, what exactly is the artillery fungus?
A: The artillery fungus is a white-rotting, wood-decay fungus that likes to live on moist landscape mulch. It is in the genus Sphaerobolus and is very common across the USA, especially in the East."
Here is a link that might be useful: Penn State University on Artillery Fungus
This post was edited by Strawberryhill on Sat, May 4, 13 at 11:29
I'm an experimenter, and not a theorist. I check by doing it, rather than debating. Check out the below picture of Radio Times, prone to fungal diseases. It's 100% clean mulched with horse manure, and dusted with corn meal. Picture taken after 7 days of non-stop rain in 2011 fall:
Also see black spot infestation of my Impatient annual flower, taken at the same time:
Please cite a science-based source about the effect of soil pH or horse manure on black spot of rose.
Yes, it is known that certain harmful soil fungi (eg crown rot of delphinium) are deterred by alkalinity, but here we are concerned with black spot of rose.
It's best if you test it for yourself, Michaelg. I understand that Bayer Crop Control manufacturing plant is located in your state, North Carolina. Bayer Corp. also has a plant in Kansa City. I understand where the strong opposition to organic ways coming from. I already tried Bayer spray and didn't work in my last house with acidic clay.
I took my microbiology class in college and applied it to my OWN climate and soil. Plus I want to use corn, to support the local farmers here, rather than Bayer company from Germany. That's why I experimented with cornmeal.
Also the pH of horse manure varies. In my cold zone 5a, the stable here uses lime to deodorize their stall, raising the pH of the horse manure to pH 7.4 in spring and way up to pH 8 in late fall.
Someone else reported a neutral to slightly acidic horse manure ... that pH level is great for fungal germination.
Any info. I give would be useless if a particular eco-system is disturbed by the use of chemicals, where all good bacteria is killed. Any info. I give would be unless if people are interested in debating, rather than trying it out.
I don't debate, I just do it. It's best if you just do it, and check out for yourself.
1) Clean out all decayed old mulch & dead leaves.
2) Get a bag of limestone pellets and mulch one rose with that.
3) If you can get horse manure on woodchips/sawdust bedding that dries out fast, it's great since it has potassium plus trace elements (copper is also a fungicide). Test the pH of the horse manure to see if it's alkaline.
4) Get whole-grain corn grits, and grind in a coffee grinder. Refined corn-meal is useless (I tested it already). I have a flour grinder that I use for whole-grain corn from the feed store, alkaline pH of 8.
5) Dust the 1/3 lower part of rose bush with corn meal, and dust the surface of soil. That would make the surface to be pH 8. Rain water is acidic at pH 5.6, more so on the east coast.
6) If a bout of rain washed all the corn meal away, dust it again. Corn meal also supplies nitrogen to the soil.
My neighbor grows roses the easy way: She planted nothing but 30+ Knock-outs, and mulched them with lava rocks. They are 100% healthy.
Below is a link to an agriculture study that showed the use of sulfate of potash (low-salt potassium fertilizer), and mulching with lime pellets BEAT using fungicide alone in soybean production.
Here is a link that might be useful: Lime, fungicides shine in test plot
This post was edited by Strawberryhill on Sat, May 4, 13 at 13:05
My soil is ready to mail and I am going to run my own test with the kit I have from Lowes or HD. I forget where I got it but it will be interesting to see how close they come. On the search for lime pellets now but I have a question about the cornmeal. I spread some in my garden but it only made my dogs want to dig around in it and I wondered if it would attract deer. I am interested in dusting with ground grits but I'm not sure how to do it. I have never dusted but I remember my grandmother dusting with something in a pillowcase. Will the grits grind fine enough to use a pillowcase? Also someone told me this weekend cedar trees were terrible to have around roses. That you would always have BS if you were close to cedar trees. Has anyone heard of this. I have many cedars creating a border between my house and the house next to me. Am I going to have to get the old chainsaw out?
Cedar trees can cause apple-cedar rust which is common around apple and crabapple trees. I have never heard of it causing BS on roses.
I don't know if cornmeal will attract deer but it will attract vermin which is something I'm sure you don't want.
Psk8er, just a word of advice. Before you go spending a small fortune on lime pellets(they can be expensive), wait until you get your soil test back. Use that as your next step on how to treat your soil and roses.
Thanks, I will wait. It is just pouring down rain and 50 degrees out there and I want to see some blooms!
Psk8er I'm south of Nashville and if you are 7b you must be North Alabama, 1-3 hours south of me. I can't give you much first hand experience, but if you are looking for black spot resistant varieties for this area I'd recommend you look at the list that Jean Harrison put together of roses she grew in her no-spray urban garden in Nashville.
Here is a link that might be useful: Thread w/Jean's list
Subk3 you are correct and thanks for the link. Do you believe out the entire list I do not have one of them? I will certainly pay more attention to this in the future.
Hi Psk8er: When I used refined corn-meal from Walmart, that attracted insects. But when I grinded WHOLE-GRAIN cracked corn into dust, it stuck to the leaves tight, and there's a very thin layer on the ground, no problems!
The cracked corn can be grounded into dust with a coffee grinder, then I use a flour sifter to dust only the lowest core center of the bush, or the lowest 1/3.... it's thorny in there, and animals can't get inside.
Whole-grain corn meal is also sold for $2 for a bag in the health food section (Bob's Mill or Arrowhead brand). You want it dusty, or fine particles. Its alkalinity counteracts acidic rain water at pH 5.6. Baking soda can hurt with its salt-content, corn dust is harmless, and also supplies nitrogen to the soil.
Sulfate of potash (high potassium, low salt) helps plants to fight disease. Both calcium and potassium regulate the integrity of cell membrane, to prevent fungal invasion. Mulching with limestone provides the calcium.
In acidic soil, potassium, phosphorus, and calcium are often deficient in soil. Since you have clay soil, magnesium is plenty once the pH is corrected.
Lime stones are sold for $3 for a big bag at stores here. It's cheaper and lasts longer than lime pellets. Its high pH prevents fungal germination, plus lime stones dry out fast. My neighbor uses white limestones to mulch ... looks clean & pristine.
When acidic rain water goes through limestone, it will add calcium to the soil. My B.S. is in Computer Science, minor in chemistry. The chemist in the soil forum also confirmed that rain water can corrode limestone and provides calcium to the soil. I already tested it with our week-long rain here, there are corroded lime particles where the gutter drains.
Gypsum also supplies calcium. Gypsum is calcium sulfate, its neutral pH won't deter fungal growth, and it's expensive.
I also found a link on how crops grown on red clay in North Carolina give the highest yield with potassium and phosphorus fertilizer (most often lacking in acidic soil) .... but a surprise DECREASE in yield with nitrogen fertilizer. Chemical nitrogen fertilizer is highest in salt, compared to potassium or phosphorus.
Salt in chemical nitrogen fertilizer drives down potassium. There's an inverse relationship between salt and potassium. Salt damages cell membrane of plants, versus potassium maintains osmotic pressure of cell, and helps with mildew as well.
See the Australian chart below for nutritional deficiency:
Here is a link that might be useful: Chart for nutrient deficiency in soil
This post was edited by Strawberryhill on Mon, May 6, 13 at 22:07
I am in Alabama, south of Birmingham. I have about 60-70 roses, mostly teas and chinas. I have not sprayed anything stronger than vinegar in the 12 years I have lived here. It is all about finding the right varieties, imo. I mulch deep, feed with organics, compost, compost, compost, and tolerate some BS, especially by the end of the summer. If a plant will not thrive and is a BS magnet, I get rid of it. There are plenty of other roses to choose from. If you need an Alabama source for antique roses and advice, try Petals from the Past in Jimeson, AL. Good luck!
Thanks, Collinw, for a great testimony of no-spray from AL like Psk8er. Another person in Alabama in the English Roses Forum watched a video where it showed that either extremely acidic, or alkaline ... both discourage fungal growth.
Hi Psk8er: I forget to answer your question regarding your cedar trees by the roses. Cedar leaves are acidic, pH 4.6 to 5, the range where fungi outnumbers bacteria.
Gardenguides.com wrote: "The leaves falling off your cedar tree, can actually increase the acidity of the soil. If you have a particularly heavy layer around the trees, consider raking the materials away from your cedar trees or using an agricultural lime to counteract the acid released into the soil as the detritus decays."
pH of vinegar is 2.2 (strong vinegar) to 4 (apple cider). pH of baking soda is 8.3, and pH of WHOLE-GRAIN cornmeal is 8. Here's the research that I posted earlier:
Contrasting Soil pH Effects on Fungal and Bacterial Growth ��" 1 by Department of Microbial Ecology, Lund University, Sweden . 2. Soil Science Department, Rothamsted Research, United Kingdom. ABSTRACT
The influence of pH on the two principal decomposer groups in soil, fungi and bacteria, was investigated … ranging from pH 8.3 to 4.0, within 180 m in a silty loam soil.
The growth-based measurements revealed a fivefold decrease in bacterial growth and a fivefold increase in fungal growth with lower pH. Below pH 4.5 there was universal inhibition of all microbial variables."
Here is a link that might be useful: Soil pH effects on fungal and bacterial growth
This post was edited by Strawberryhill on Tue, May 7, 13 at 10:01
Thank you Strawberryhill and collinw. I will check out Petals from the Past.
I already know that spraying is not going to hold BS to what I consider an acceptable level so I have nothing to lose. Strawberryhill, you certainly sound like you know what you are talking about and your roses are beautiful. I'm going to follow the directions of EarthCo when I receive my test results, sprinkle with cornmeal, neutralize the soil under my cedars, remove the pine mulch and replace with limestone pebbles. I will let everyone know how this turns out. I know I have sprayed, never water from overhead, have good air circulation and plenty of BS. What have I got to lose?
Thank you again to everyone that has given their time to help me. It is very much appreciated.
Hi Psk8er: Removing that pine mulch would help. Dry pine mulch is acidic at pH 4.5, and stays wet long. But once rain water, at pH 5.6 pass through the pine mulch, it can make the soil very acidic and burns roots in contact.
Below is a excerpt from the fig forum: "Today, my pond water is at 8.33 pH and the standing water in a plastic pail of pine bark chips is 3.45 pH ... I showed my wife there were pine bark fines clumped around the dead and rotted roots. .. Today, I say that the acid in the fines might also have played a role in the plant root loss. "
I'll repost the procedure I wrote to get the pH of any soil from your garden using $1 of distilled water, and 50 cents of red cabbage. It's handy to have a few leaves of red cabbage in the refrig., to check for the surface pH of your soil.
Good luck to your garden, Psk8er. Collinw is right in using compost ... it's high in potassium and phosphorus, both lacking in acidic clay. I also agree with Collinw in feeding with organics, and stay away from chemical nitrogen, such as urea with a salt index of 74.4, ammonium nitrate (in Osmocote) of 104, and ammonium sulfate of 88.3. It's like dumping salt on your rose bush when chemical nitrogen is used.
I'm not so sure about limestone pebbles as mulch. Think about walking on concrete in the summer in bare feet. They are going to heat up and radiate that heat back on your plants. You might end up frying them on a typical Alabama August day!
The other problem is if it doesn't work out for you you are then stuck with them in your garden until you remove each one by hand...
I think Strawberry is quite a bit North of us in zone 5, so while it might work for her you might want to think twice about it.
This post was edited by subk3 on Tue, May 7, 13 at 14:41
Great point, subk3 ... we have 79 degrees temp. today. I went out to touch the limestone, slightly warm, but the soil beneath is wet and cool. Since we have lots of lime stones here .. I used them for the past 12 years to mulch.
No problems whatsoever mulching with lime stones in hot summer, be it annual flowers or baby trees.
Our temp. in July & August is 90 to 100 degrees. I moved those stones with bare hands in hot days, the soil beneath was always wet with earth worms.
My neighbor uses black lava rock with the best-looking roses in her garden. I used red lava rock one time, it broke down too fast. Lava rocks are neutral in pH, they stay dry after a rain.
Roses in my zone 5a are buried deep below ground level. Cantigny roses park here with 1,200 roses have just bare dirt, no mulch. It's less watering with roses being buried deep. Below is Carefree Celebration at Cantigny Park, taken after frost in October. Roses here bloom well, even when buried deep.
This post was edited by Strawberryhill on Wed, May 8, 13 at 9:10
Saved again, thanks Subk3. Will come up with a different plan for mulch but this pine bark is leaving here! I would never have anything without mulch. Just have to give it some thought.
American pine mulch (bark or needles) is fine. It is what most rose growers use. (Some European pine species are phytotoxic and not suitable for mulch.) My roses grew great under two inches of pine bark. I have never heard anyone say otherwise except StrawberryHill.
I love Strawberries willingness to try a variety of things in her garden and she must have a long list of clipped sections of posts or a fabulous memory. Lots of interesting quotes from others on what works for them in their gardens.
But I too would be hesitant in using stones as mulch. Think about the amount of work involved if you need to dig a hole in the bed with the stones. You have a good half hour of work sitting there picking them up one by one and putting them in a bucket to reach the soil. It is easier if you have some kind of weed cloth other them-but the weed cloth is another problem in itself. (I have been sitting with a bucket day after day picking up the stray gravel at a rental house and had the fun of picking it up out of a green house floor too a couple of months...fun...not) And just digging in the gravel and mixing it in only makes your soil harder to dig in for the future.
My gravel walkway stays damp under the stones too. But the top side is hot and reflects heat back. My boss's long long long rose lined gravel also gets very hot. Her roses look wonderful BUT the gravel is not under the roses (ringed to keep it out) She is closer to the ocean than I am and gets some nice cool damp ocean breezes. The heat of the gravel and driveway seem to get her roses blooming early but most fry pretty quickly in the day.
It might be better to ask a successful local organic gardener (check at farmers market if you have one) what works for them in your area.
In my neck of the woods, stones/rocks are a no no as a mulch in sunny area. We get too hot, it would fry the poor leaves. I do have a two rock beds, one that has river rock, I grow different types of thyme in. I did try lantana but I ended up having to move it because the heat from the rock were roasting it. Now lava rock is totally different, I can tell you its not fun to walk on and its a totally pain in the ass to get out of garden bed. I use pine mulch for years now, did a soil test in January. It had no effect on the ph of my clay soil which was neutral.
Thank you all for the info. We have a hot day 81 degrees. I went and touched different rocks in the neighborhood. Most hot are the pretty multi-colored rocks. Second hottest are the white rocks. Third hottest is the limestone (yellow), feels as hot as my dry limestone clay. The lava rocks aren't that bad.
Lava rocks add micronutrients to the soil .... years ago I used red lava rocks with the best flowers. My neighbor uses lava rocks and water her roses more than I do, but hers look better.
Different soil & climate has a factor here. Michaelg is sandy soil, and not acidic clay like Psker8. Water drains out of sandy soil fast, so it doesn't ferment pine bark the way wet clay soil does. In my last house of acidic clay, the roses were less robust and had more diseases. I mulched with pine bark back then.
Two people in the fig forum used CALIBRATED meters and ended up with the same acidic result of pine bark soaked in water, below 4. The acid damaged plant roots. Less roots mean less nutrients to fight disease.
I did a pH test in a water-logged pot with pine bark, it's very acidic below 5. When bark is dry, it's more alkaline than when it's wet. That's why dry corn dust is pH of 8, versus fresh corn at 7.3.
Even the $200 pH meter needs to be recalibrated, otherwise it gives false neutral reading. The meter & soil kits I bought registered neutral for my limestone clay, and ONLY the professional test done by EarthCo. matched the pH reading gave by the red cabbage juice.
Alabama annual rainfall is from a low of 53 to a high of 70 inches per year, that's way-more than my rainfall of 40" per year (we also get 23" of snow). Rocks aren't bad in a wet weather, vs. dry heat that intensifies the heat.
Cheapest mulch is hard wood mulch, made from recycled wood, dyed red. Two of my neighbors have that, and I haven't seen mushrooms growing on them. The hard wood mulch is the same stuff in the horse manure bedding, which dries out fast. Less surface moisture means less fungal germination.
The free village tree-bark mulch sprout mushroom here. I haven't tested cedar mulch, which repel insects. Cypress mulch sprouts mushroom here.
Below is a picture of the effect of a poor-draining pot, 1 week of non-stop rain, and mulching with pine bark. The band came from a nursery which used a medium of pine bark and Osmocote. Symptoms of low pH: thin & whitish and wilted leaves, calcium, potassium, and nitrogen deficiency. First, I used a high-nitrogen SOLUBLE fertilizer, it got worse. Then I used blood meal, it didn't help ... then I did a pH test.
I was foolish to put pine bark on top, thinking that it would lower my alkaline tap water, I didn't realize how acidic the soil is, until I did a pH test with red cabbage ... same pink color as fresh pine bark.
Here is a link that might be useful: Fig forum and acidic pine bark results
This post was edited by Strawberryhill on Wed, May 8, 13 at 16:09
It is not just me who finds pine bark mulch highly satisfactory, it is professional horticulturalists and probably millions of gardeners. There is nothing wrong with it, and it will not significantly acidify your soil. Anyway, roses prefer a slightly acid pH of 6.0-6.7, which is the range that maximizes the availability of nutrients.
I am not sure what is meant by "limestone pellets," but I urge you not to mulch your roses with pelletized lime. This is fine-ground limestone pressed into pellets so it can be delivered to lawns in a spreader. Enough fine limestone to be considered a mulch would in time raise the pH way out of the roses' comfort zone and could have a ruinous effect. I would not recommend mulching with gravel, either. Eventually it will become mixed with the soil to prove a permanent nuisance to the gardener. And, unlike a mulch of organic matter, it will not help the soil. A decaying layer of bark, leaves, or chips adds humus continuously and encourages earthworms. It will eventually influence the soil for several inches down into the root zone.
Let me repeat, we have no reason to believe that the type of mulch has any effect on blackspot disease.
The cheapest mulch around here is cypress which I like better than hardword. However, it was recently brought to my attention of the ecological issues with cypress mulch so I will no longer be buying it. I have no idea why the pine mulch is having very little to no effective on my clay soil. But the results did explain why my azaleas were doing so badly 2 years after I had moved them.
Michaelg, if you want to endorse Bayer spray, I respect that, since Bayer Crop-Control plant is in your North Carolina. But it's not fair to speak for everyone else, when our soil/climate are so different. To force the same rule on everyone else would NOT be democratic.
I only speak for myself, I don't speak for others. All I know is that my roses have zero diseases given those conditions. The rose park here sprays every 10 days in humid weather, they still have black spots on their Christian Dior Hybrid Tea. Fifteen years I sprayed with Bayer and had rampant BS, with roses half-naked.
Why do I get so much negation for everything I do, from using free horse manure, to supporting local farmers who grow corn? It's my personal choice of NOT supporting Bayer Corp. from Germany .. check out what Bayer did during the Holocaust with Jewish extermination, plus the effect chemicals have on the environment.
That's why I don't spray, and focus on finding out what works in my particular soil climate. I refuse to let others speak for me either.
I had the best result when I mixed red lava rock into my clay ... all 3 neighbors came to compliment on my wildflower bed, with brilliant colors. Lava rock has iron, calcium, phosphorus, potassium, and many other minerals. Later years I dumped too much leaves on that bed, and it went downhill. There's a site on growing best orchids with red lava's nutrients . See link below for nutrients in lava rock.
Here is a link that might be useful: What is lava made of?
This post was edited by Strawberryhill on Wed, May 8, 13 at 18:03
"Michaelg, if you want to endorse Bayer spray, I respect that, since Bayer Crop-Control plant is in your North Carolina. "
Strawberry that's a ridiculous assertion you are making--that Michaelg is "endorsing" a Bayer product because it happens to be produce in NC. This would be the same very popular product that is recommended on this forum over and over by a multitude of other posters, but suddenly Michaelg is suspect. Seriously?
I haven't been growing roses in the area of the OP long but this is what I know: very, very few people do so successfully with our blackspot pressure without spraying. Those that successfully don't spray have generally gone to great lengths to select BS resistant roses. Something the OP has not done.
I don't think Michaelg advocates gardening practices based on the location of a fungicide company in his state. Michaelg has been posting on this forum a long time and I have always found his advice to be sound and usually very similar to what I do in my Kansas garden. He advises based on garden-worthy results, not on capitalist concerns about keeping a fungicide company profitable in his state.
And no, I am not supporting Michaelg's gardening practices because there is a fungicide company in Kansas City. If there is, I didn't know that until today--so Bayer could not have been influencing my outlook--although I do occasionally use Bayer fungicide and recommend it to others with BS problems if they are looking for an effective fungicide. I usually give instructions on how to reduce the use of it also--because I don't really like spraying at all.
I think you underestimate how "organic" some of us are in many of our practices, even though we sometimes use Bayer fungicide.
I will back michaelg on the claim that informed gardeners throughout our country use pine bark for mulch. If someone wants to use something else for mulch, so be it--but that doesn't change the fact that knowlegeable gardeners have good reasons for preferring pine bark mulch and a newbie might do well to try out the tried and true gardening practice that has worked so well for so many gardeners. But that is up to the newbie to decide.
If somebody wants to float theories or describe experiments, however odd, that's fine. The reason I have spoken with "so much negativity" is that SH is giving. . . let's say, eccentric advice to a newbie who is in no position to know how eccentric the advice is.
Also I have been suspecting for some time that StrawberryHill is. . . let's say, a fictional character. From time to time these have shown up on this board with the purpose of stirring up quarrels among the regulars. The fictional character cultivates e-friendships for a while and then provokes someone into criticism or angry self-defense, causing others to rise to defend the FC, etc.
The assertion that Michael gardens in sandy soil baffles me...i live near him and my entire yard is a rockpile bound together with clay. If ONLY it were sandy. Sigh.
My garden is a terrace, not on grade, and one of my beds is artificially mixed sandy loam. Others are mostly clay or mostly silt.
My goodness I never meant for any of this to happen. Again I thank everyone that has offered advise to me and I deeply regret that my question might have caused hard feelings among members here long before I even discovered this forum.
I am just going to slow down, take a step back, a deep breath, have a cup of tea and re-evaluate the situation. I appreciate every opinion and or suggestion. I have all of the information everyone has offered and understand what everyone is saying. If I make a wrong decision it is all on me. Let's just enjoy the season while we have it :-)
Psk8er, I wouldn't trouble yourself. Some threads have a tendency to take on a life of their own, and there's nothing to be done about it. No worries. :)
Houston is right, this isn't your fault. Sadly, this happens from time to time. You've already taken the first step by having your soil tested. Let that be your guide. Goodluck.
Well..hmmm..I am not a scientist. But when I planted my rose garden in a raised bed 4 years ago I added lots of compost, gypsum, lime..rose growing mix..mushroom compost a few times and manure. I am in the soggy PNW and I grow lots of moss around here. But I did not want to spray..I did use a dormant spray a few winters and a few times wettable sulfur. This year I have not fertilized, or sprayed. My roses..the oldest one look great. I truly believe it is about the soil and also trying to stick with stronger roses for your area. It works. It's the soil people..that and PATIENCE.
The following was stated: "Let me repeat, we have no reason to believe that the type of mulch has any effect on blackspot disease."
"In 1992, less blackspot developed on plants with oat straw or pine straw ground covers than on those with landscape mat or bare soil. In 1993, lowest disease severity was observed on plants with oat straw ground cover."
Here is a link that might be useful: link for above
Regarding the acidity of pine straw mulch, I was able to find a very complete study:
"Pine Straw (Pine Needle) Mulch Acidity-Separating Fact From Fiction Through Analytical Testing"
For oat straw mulch, I could only find the vague term neutral,
Here is a link that might be useful: link for pine straw acidity
Thank you, Henry for the info. My point is that when it's DRY AND ALKALINE, BS can't germinate. Oat straw and pine straw dries out fast after a rain. I have pine needles in my garden, it's test neutral in pH. Pine BARK is different, it stays wet and acidic for years.
My bare soil is tested pH 7.7 more alkaline than pine needles which is neutral after 46 days (see the below link).
Pine needles dry out faster than bare dirt. It's the pine mulch or pine bark, that stays wet longer after a rain, I pick up a piece of 2-years old pine MULCH and tested its pH: very acidic, versus pine NEEDLES or straw, that's neutral after 1 month. Optimal condition for blackspots growth: 7 hours of wetness, and from pH 4 to neutral.
Fungi doesn't like dry and alkaline, I took both microbiology and biochemistry in college. See excerpt below on pH of Pine needles, which is different from pine bark: "From this round of tests, it is clear that the fresh green needles leachate was initially acidic at 4.5, but following several simulations of rain and drying cycles over a few weeks time ... Over a period of 46 days, the needles were no longer acidic, with the pH being that of distilled water."
Here is a link that might be useful: Pine Straw info.
"Those interested in ornamental plants were not left out of the Field Day. Kira Bowen, associate professor of plant pathology at Auburn, discussed a study of new ways to control blackspot in roses, which leaves black spots on the leaves and can defoliate plants. She noted that fungicidal sprays are the best controls for this disease. She noted that using a mulch, such as pine or oat straw, that sponges water away from the plant also will help control this disease.
"These mulches keep rain and water from splashing up on the plant," she explained. "The disease is spread when water splashes it onto the plant, so certain mulches can help stop its spread."
Here is a link that might be useful: link for above quote
The link to the complete mulch - blackspot article is given below.
Here is a link that might be useful: Auburn link
This is for Straberryhill...
Wow! I am so impressed (and jealous) looking at these beautiful rose bush! Great Job! What kind is it?
But the bar graph in the article shows pine bark as scoring better than pine needles, not worse!
Mulch is better than no mulch because a fresh mulch covers fallen leaves and leaf fragments that may be a source of spores. Organic mulch might be better than landscape fabric because the plastic encourages more spattering. BS spores are moved around primarily by splashing water and, I believe, the gardener's hands and gloves. The spores are relatively heavy and sticky.
Hi ND1964: Thank you for your kind words. The 1st shot of 3 rose bushes are very disease-resistant: Francis Blaise, Liv Tyler, and Evelyn. The shot with corn-meal dusting is Radio Times (too thorny!). The last shot at Cantigny rose park is Carefree Celebration, they use zero mulch, since we have alkaline clay and wet climate.
We have 2 weeks on non-stop rain with mushroom in the lawn. My 52+ own-root roses are 100% clean ... if you want to know why, check out the English Roses Forum where I listed experiments for international folks. See link below.
Own-roots are healthier than grafted on Dr. Huey for my zone 5a. Roses Unlimited in SC has a sale 1st week, or 2nd week, or 3rd week of June, depending on the weather ... where it's 1/2 off, only $8 per gallon last summer. They come big & healthy with blooms.
Here is a link that might be useful: English Roses Forum and general care of roses
This post was edited by Strawberryhill on Sat, Jun 1, 13 at 23:10
The following was stated: "But the bar graph in the article shows pine bark as scoring better than pine needles, not worse!"
H.Kuska comment. I wonder if in preparing the graph the captions were mixed as when the authors in the other paper discuss the results they single out the oat straw and pine straw: "In 1992, less blackspot developed on plants with oat straw or pine straw ground covers than on those with landscape mat or bare soil. In 1993, lowest disease severity was observed on plants with oat straw ground cover."
In the days of manual type setters, errors of that type were known to occur and when the authors (my self included) checked the proofs we read what we know we wrote instead of what was actually before us.
It would have been helpful if they had included the table that containe the data used in the graph (with standard deviations).
Please note, the idea that the captions may have been switched is just a maybe.
Hi Henry: Thank you for the info. I was puzzled why my band in pine bark from the nursery looked so sick in the picture I posted up the thread.... I also put pine mulch on top of the pot. I scraped off the mulch when I tested the pH to be very low.
Here's an excerpt from the link below: "Low oxygen composting of pine bark (anaerobic respiration) causing very low pH. This can occur in pine bark when mold (mycelia) develops in a band 24 to 30 inches below the surface of the pile. This creates a cap that seals off oxygen. Anaerobic respiration can occur producing acetic acid (vinegar), phenolic and alkaloid compounds toxic to plants. The pH may drop as low as 2.0, which causes nutrients (fertilizer salts) to be flushed from the pine bark. These can also be toxic. Check the pH before planting. If low pH is a problem, wet and aerate the pine bark. After three weeks the pH should return to about 4.0.
Mold in the bark which repels water. Pine bark in dry piles may develop high fungal populations recognized by clouds of spores when disturbed. Once spread out and irrigated, a mold (mycelia) grows rapidly which repels water. Newly set plants may dry out and die. "
Last year I put pine bark in a hole to break up my rock-hard clay. Yesterday I dug that hole and found white mold. I was puzzled why that hole is so dry. Never mind that we have 2 weeks of constant rain. Pine bark is the slowest among mulch to decompose, but it can destroy roots with its acidity when too much is piled up.
From another University of Georgia document: pine bark has a pH around 4, with approximately 13% water retention when fresh, and 21% water retention when decomposed.
Here is a link that might be useful: University of Georgia on pine bark
This post was edited by Strawberryhill on Sat, Jun 1, 13 at 23:55
I found a more complete article describing the mulch experiment work of Dr. Kira Bowen at Auburn which was mentioned above by Dr. Kuska.
The experiments were done in the early 1990's over a three year period comparing blackspot on several roses that were sprayed with the fungicide chlorothalonil in beds that were mulched w/ pine bark, pine straw, oat straw, landscape fabric and unmulched.
There was very little difference in disease levels among the roses planted in the various organic mulches, but disease increased where the beds were unmulched or had landscape fabric. The chart in the article indicates that roses planted w/ pine bark mulch suppressed disease a little more than roses planted w/pine straw, but a little less than oat straw. The differences appear negligible among the three organic mulches. The article appears in a pdf document of a document called "Highlights of Agricultural Research" Vol. 42, No. 2, Summer, 1995. Disease certainly did not increase using pine bark mulch. Disease w/pine bark mulch was less than pine straw. The differences appeared negligible to me, however.
I gardened in north Alabama in the Huntsville area for about five years growing 100 roses in acidic red clay. I mulched with pine straw, pine bark, leaves and even grass clippings. I did not spray fungicides. Among all of the roses that I grew, the most disease resistant were the tea and china roses. Many of them are on Jean Harrison's list that subk listed above.
Interestingly in the 1913 article Dr. Kuska links in another thread on "blackspot of historical interest" the r. indica roses, or teas and chinas, are noted to be disease resistant to blackspot as well.
I now grow about 100 or so roses in a very mild, wet climate in the Pacific Northwest. I mulch with leaves, wood chips, grass clippings or whatever else I can find, including manures of various animals. Much of my garden is covered with wet leaves from autumn through early summer. My soil is also very acidic.
Again, what I find is that the roses that are naturally disease resistant in this climate do not get blackspot regardless of mulch type. The 1913 article makes note of the same thing as I have found. Gallicas, rugosas, albas are disease resistant. Some moderns are. Portlands are. The mulch makes no difference as far as I can see; it decays and improves the soil, and soil quality seems to make a big difference in the health, vigor and disease resistance of a plant, assuming the rose is disease resistant in the climate anyway.
I chipped wood and used it as a mulch in a rose bed last fall. Subsequently many mushrooms appeared in a very wet, cool period. The mushrooms died over the winter, the chips have decayed and that bed has some of the richest soil in my garden. I have some very healthy roses in that bed where the wood chips have decayed and the mushrooms died. I am assuming the mushrooms will return next winter as their fruiting bodies go pretty deep. This does not scare me. They are an indication of healthy soil.
What Strawberry Hill does may work in her zone, however, you live in Alabama and have red clay. You need mulch. If you can get composted horse manure, that is great, but that is an amendment, not mulch. In your yard, it will bake in the hot sun and turn to concrete, just as your clay soil will.
Pine bark mulch is fine. I don't like pine straw for rose beds because I am always walking on it and it tracks into the house. I do use it on hilly areas and it's fine.
I used to use the generic pine bark nuggets, but I recently tried using the new engineered mulch that is supposed to help with directing water to the ground/roots of plants rather than absorbing it and preventing it from getting to the ground. I have noticed a difference.
Teas and noisettes are your friends, look into them and get these roses. They do best in our area and are resistant to BS. They will get spotty and lose some leaves, but they will not be as bad as some hybrid teas that honestly cannot survive without spraying in the hot/humid SE without spraying.
There is a rose person, The Redneck Rosarian, who lives in Alabama and is on Rose Chat. You should check out his blog. He will probably have a lot of info that would be helpful to you:
BTW, the link above from the University of Georgia is about growing blueberries in pine bark, not using it as a mulch for roses. The southern highbush bluberry industry in south Georgia and northern Florida uses prodigious amounts of pinebark as soil. This is because the native soil is many times not suitable for blueberries. They do best in acidic soils of 4-5 ph.
Thank you Buford and Gean for the info. Everyone soil and climate is different so I never speak for others, I only speak for myself, and from actual experience.
In my last garden of ACIDIC HEAVY CLAY, mulching with pine bark hurt my roses' roots. They were tiny when I dug them up. Kim Rupert discussed about bigger roots mean better disease-resistant in his breeding program.
Here's a discussion in Fig forum on how acidic pine fines hurt young roots: "Today, my pond water is at 8.33 pH and the standing water in a plastic pail of pine bark chips is 3.45 pH. I was not surprised, just deflated. I should have known that the pine bark would work to lower the soil pH. I dumped a planted nursery pot the other day and ran and showed my wife how it seemed there were pine bark fines clumped around the dead and rotted roots".
Now in my present house of HEAVY alkaline clay, I mulch with horse manure on a bed of sawdust and recycled wood chips bedding. Nice and fluffy on top, zero gunking nor made into concrete in our hot summer 90 to 100 degrees. Recently I moved Golden Cel. ... its root is huge, and the top 12" where I piled manure/woodchips is nice and fluffy.
Below is the base of Golden Celebration, picture taken last October, before frost. It's always clean here, not a trace of black spots. The horse manure on woodchips bedding has a pH of 7.5, slightly less alkaline than my soil of 7.7.
Here is a link that might be useful: Pine bark discussionn in Fig Forum
Here's the base of Evelyn, taken in this year's wet weather. It's also mulched with horse manure on wood chips, nice and fluffy and DOES NOT become concrete on top.
Evelyn has zero diseases going into winter, and 100% clean now. Paul Neyron and Comte de Chambord are also clean, but I didn't put horse manure on those 2, just bare dirt. My soil pH is 7.7, black spots can't germinate in that alkaline range.
This post was edited by Strawberryhill on Sun, Jun 2, 13 at 10:01
From that same thread:
The pH of pine bark fines generally ranges from 4.7 as a low, to 5.1 as a high, so your finding a pH of 3.45 is confounding, especially since pH is measured on a logarithmically inverse scale. I.e., a pH of 3.45 is 10 times more acidic than a pH of 4.45 and 65 times more acidic than pine bark that falls within the normal range at 5.0.
Figs will grow just fine in an acidic media, if the nutrient solution pH is reasonable. The pH of a container substrate is much less important than the pH of mineral soils.
Again, that thread is about growing fruits in containers of pine bark as substrate, not as mulch. It's a completely different situation.
There is clay and there is clay. The SE has red clay which is acidic. However, most people here, and most rose growers, use pine bark mulch. The Consulting Rosarians in my local rose group recommend pine bark. I doubt as a mulch it adds too much acid to the soil. It's possible that the clay you had was very acidic, or you did not amend enough with organic material. Clay can be hard to grow in if not kept friable and moist. Adding amendments to cut up the clay and keep it porous is very important. If not, the roots will have a hard time getting through the thick soil and will grow very close to the surface, perhaps even in the mulch and that may have caused them to be stunted.
The pile of horse manure here is taller than a 1-story house. It becomes an environmental issue when that goes to landfill, rather than folks' garden... I learned that from Kim Rupert. I post pics. to show that horse manure works just fine, and doesn't become concrete on top.
Roses still bloom well at alkaline range. Cantigny rose park with 1,200 roses is 15 minutes from me, alkaline clay. Chicago Botanical garden with 5,000 rose listed their pH of 7.4 with composted leaves. My garden is highest at pH 7.7, leaves are pale but very healthy, and roses bloom well.
Below is Christopher Marlowe, planted with a big pile of horse manure at the bottom, after I removed all lime stones. I also mulched 4" thick with horse manure. He gets only 4 hours of morning sun:
I have no doubt that roses with manure as a soil amendment in the soil and/or as a mulch on top can grow fine. I don't think anyone disputes that possibility. So why are you arguing? And about what?
Most people don't have access to horse manure. Alfalfa is the next best thing. It's actually pre-digested horse manure :) But I would not use it as a mulch.
I don't mulch directly under my roses, I leave that bare, but it's been amended so much and is it constant shade from the roses, so it doesn't need mulch. But beyond the drip line, every thing is mulched in pine bark (or was until that storm that swept all my mulch away....). Alfalfa will not cause black spot. And if alfalfa is acidic, then so is horse manure.
My main criteria for a healthy rose soil is when I find that the rose roots have formed Mycorrhiza fungi associations.
Here is a link that might be useful: link for wikipedia discussion of mycorriza
I think harborrose makes the key point about the Kira Bowen article: differences among the organic mulches appear to be negligible for any practical purpose. Are they even statistically significant differences? And the findings contradict the claim by SH that pine bark mulch contributes greatly to blackspot problems or that getting rid of bark can turn defoliating roses into blackspot-free, no-spray roses. So I return to my assertion that we have no reason to believe that the type of mulch has any effect on blackspot. (I do not think of landscape fabric as a normal mulch.)
If, as Henry speculates, the captions for bark and needles were reversed, there would still be no substantial difference.
An important point that got lost in this discussion is that most transmission of blackspot is from leaf to leaf, not ground to leaf. Also blackspot overwinters in spots on green canes which provide reinfection to the spring leaves if there are no overwintering leaves. Infected fallen leaves are likely to play a major role only when the rose has been pruned nearly to the ground.
Back when we had subzero winters here, I pruned hybrid teas to a height of zero to eight inches. Then I rarely saw any BS spots before the end of the first flush. With hardy shrubs and high-pruned HTs, BS started much earlier. Unsprayed roses can be defoliating by the end of the first flush. This is because the overwintering canes have BS lesions (often visible as purple spots) that deliver spores conveniently to the new growth.
The importance of cane infections in transmitting BS explains why, in the Bowen study, there was only a modest difference between mulched and unmulched roses.
Stuff are acidic at first, but when it's decomposed, it goes to neutral range. The horse manure I get is decomposed. The stable in my zone 5a put lime to deodorized, that raise the pH to 7.5 and above. Pine bark is slowest to decompose, thus stay acidic much longer.
I'm doing an experiment where I mulched 2 out of 16 pots, with pine bark. The 2 pots mulched with pine bark have the slowest growth. When the root is injured by pine bark accumulated near it, it's less disease-resistant.
A second person reported the same: •Posted by lathyrus_odoratus (My Page) on Thu, Mar 25, 10 at 3:44
"I'm resurrecting this thread because I've recently had an almost identical experience....expect I've killed at least two plants and caused damage to at least 10-15 more. They are not fig trees, but what happened is so similar that I felt compelled to write about it here. Here's what I know:
-Pine bark fines test at about 3.7 or so (same as the person who started this thread) ...." See link below:
If you google "horse manure pH", folks in the Soil Forum report a much higher value than mine, at pH 8. All I know is my 52+ own-root roses are 100% clean with either horse manure at pH 7.5, or my bare dirt at pH 7.7. I don't spray whatsoever.
Below is Pat Austin, taken today after 2 weeks of non-stop rain. She's always clean even in late fall.
Here is a link that might be useful: PIne bark discusison in fig forum
You can mulch with anything you want but unless your roses are healthy and have a strong immune system on their own they'll still get black spot. Mulch in no way kills it or deters it from showing up when conditions are right for it. It's out there on the wind and whether you've mulched or not it will show up and grow. The key is healthy roses with high resistance not top dressings.
Yes, Seil, I'm proof of that. I use horse manure in the planting hole and I mulch heavily with it. Most of our rain arrives during our hot, hot summer months, and I have little trouble with blackspot. If, however, we have several days of damp overcast weather during our cooler months, my roses will blackspot, despite the horse manure.
I had posted the link to the Bowen full paper on Sat, Jun 1, 13 at 15:50 and then commented on Sat, Jun 1, 13 at 20:19 :
"It would have been helpful if they had included the table that contained the data used in the graph (with standard deviations)."
H, Kuska comment: However, Dr. Bowen apparently felt that the differences in results were significant as she singled out the oat straw results. "In 1993, lowest disease severity was observed on plants with oat straw ground cover."
I would expect that there are times when being able to observe the actual fields allows one to see correlations that appear less significant when transcribed to a small three dimensional bar graph. I specifically mention three dimensional as I feel that that feature makes it difficult to enlarge the graph and then read the actual values from the axis. Can anyone else (possibly with a fancy program) do it?
The following was stated: "An important point that got lost in this discussion is that most transmission of blackspot is from leaf to leaf, not ground to leaf."
H.Kuska comment. I am interested in reading what study this is based on. The 2003 scientific paper in the link below reports: "The causal organism, Diplocarpon rosae, is spread primarily by water splash and reproduces almost exclusively by asexual acervuli and conidia."
"In 1993, lowest disease severity was observed on plants with oat straw ground cover."
Here is a link that might be useful: link for splash statement
This post was edited by henry_kuska on Sun, Jun 2, 13 at 14:26
I agree with Seil and Floridarose!! You said it best. The key is strong root system, and good soil.
My clay soil is high in limestone, which releases gypsum (calcium sulfate) when rain water (pH 5.6) hits. I don't have any fungal diseases on my peach, pear nor cherry trees. My fruit trees are clean, no need to spray.
Calcium and potassium strengthen plant tissues, so I don't have peach-leaf curl disease. I don't have botrytis nor balling in my roses either. My neighbor grows 100% clean hybrid teas, no mulch, just bare dirt. I'll get my soil tested again, since the last time I scooped the top soil, with mostly dead grass and horse manure .... it's not accurate.
I notice that the disease-resistant roses: Kordes Flower Carpet, Eye-for-you, and Kim's Lynnie all have thick leaves. In my pots experiment, I notice that the leaves became thicker when I put gypsum (calcium sulfate) in the pot.
I have 3 disease-prone roses: Paul Neyron, Comte de Chambord, and Gruss an Teplitz. They are clean in holes mix similar to what I planted Paul Neyron last summer with Ball's potting soil: composted pine fines, lime, peat moss, perlite, vermiculite, and gypsum.
Most of my roses are green to the tip through the winter, so zone 5a isn't a factor in keeping roses clean.
Below is Paul Neyron well-behaved in the ground this year, picture taken today, he's NOT mulched with horse manure, so he's pale. Horse manure has iron and all trace elements to green up my roses.
Strawberry, I don't understand your pictures. Either you severely prune your roses nearly to the ground (which would be a major reason why you don't see much BS infection), or your pics are all of new little undeveloped roses --which means the BS problems are probably still in the future as they grow to their normal heights.
Take for example your picture of the hybrid perpetual--it looks about 6 inches tall. In my garden, a hybrid perpetual grows about 5 or 6 feet tall, not 6 inches tall.
I really don't understand what you are showing in the pictures since all of your pictured roses look undeveloped or severely pruned--not normal growth, in other words.
I'm also concerned that you are not always using terms the same way other posters are. Just a couple posts ago, you seemed to think manure as a soil amendment was the same thing as a mulch--your posters are talking about two different things when they use those terms, but you evidently are not. That makes me wonder about your repeated assertions about pine bark mulch--it's beginning to sound like you are using pine bark as a soil amendment--mixing it into the soil in the planting hole, for instance. That is NOT how your posters think of a mulch--which to them means the pine bark is spread ON TOP of the planting, not mixed into the soil in which the rose is planted. If you are indeed using a mulch as a soil amendment, I can see why you got some results that surprised many of the rest of us--because when we use a mulch as a mulch (and NOT a soil amendment) we don't usually get the results you claim to get.
Unless we all agree on the terms we are using, there is no possibility that we can begin to understand what each other is saying.
UGH too much science for me! Okay..as I posted somewhere else on this site..I made a new raised rose bed about 4-5 years ago. I added compost..different kinds..and Gypsum. Also used a good soil for Roses..made especially for roses..My garden is almost BS free this year! One more new thing we did was lay down a layer of wood chips last fall..maybe that's what's helped so much. NO SPRAY so far..and I would not use one now. I don't mind the dormant sprays as there are not so many bees around. I know at first I was trying to use safe things like Neem oil for my roses..and even that went away. My weak roses like Double Delight in a pot look like hell and Octavia Hill own root is in the shade and is lush and green this year. I think for a newbie it's just important to think about putting compost and nutrients into the soil. Good soil equals good plants..and enough with the science..I do not do anything to kill the bugs..EVER..I do pick off rose slugs..lol. I think if we are patient and the soil is good our plants will come around...
Also..Straw-years ago I lived in California and we had what we called HARD PAN soil. It was hard as a rock. We had planted 3 trees..Mimosa's...they would not grow..just sat there..and my ex got Gypsum and started throwing it around the base of those trees..it worked and eventually that Gypsum broke down the hard pan and those trees grew.
I wish I could be so confident with my companion plants to my roses..my Clematis are struggling...thin little twigs. :(
Hi Zyperiris: I'm glad to hear from you. Thank you for the info. that gypsum breaking down hard clay.
Paul Neyron was a tiny band last fall, the winter-kill was severe on that one. I was talking about MULCHING with acidic pine bark in my last house of acidic clay, with roses that black-spotted badly .... their roots were hurt by the pine bark's acidity.
I was talking about the experiment I did MULCHING with 2 pots out of 16 with pine bark ... slowest growth so far. I'll report the experiment elsewhere so I won't be nit-picked.
I do have big hybrid teas that were green to the tip. I only pruned 1/3 off in spring. Here are hybrid teas Sweet Promise, and Firefighter next to it. Feel free to put down my pictures ... I won't be around to see your comments:
I said: "An important point that got lost in this discussion is that most transmission of blackspot is from leaf to leaf, not ground to leaf."
Henry quoted that and answered: "I am interested in reading what study this is based on. The 2003 scientific paper in the link below reports: 'The causal organism, Diplocarpon rosae, is spread primarily by water splash. . . .'"
--Henry, surely you understand that "water splash" can carry blackspot spores from cane to leaf and leaf to leaf? Surely you are not asking for a study to verify that?
Horst in the Compendium, immediately after describing conidial sporolation in LIVING leaves, says, "Conidia are disseminated by splashing water. . . hands. . .insects." "The fungus overwinters as mycelia in fallen leaves or on infected canes." "The fungus does not survive in the soil" (1st ed., 10).
The fungus is not in the soil. If fallen leaves are covered with a new layer of mulch, infection of new growth in spring is going to come primarily from infected canes and old leaves hanging on the plants--carried to the new growth by splashing water. But if roses are pruned to the ground, infection will be delayed until spores from fallen leaves make their way up through the mulch and are splashed up onto new growth. Once new growth is infected, it seems obvious that the season's infected leaves (living or newly fallen on top of the mulch) become a more important source of spores than last year's fallen leaves buried under mulch.
I am skeptical of claims about the effect of soil pH or the particular type of mulch because BLACKSPOT IS NOT A SOIL FUNGUS. Blackspot colonizes the above-ground parts of a susceptible plant and lives there pretty much permanently.
Somebody's angry and not coming back? Well whatever..lol
Are you saying that if you live in an area that has winters that regularly cause die back so far that you have little cane left vs an area with a warmer winter with canes that stay viable, you would have less blackspot even with the same disease level for the area?
Not really a worry for me here, but curious how much temperatures would vary the level of disease when all else is the same.
Michael in your original statement you stated "most" ( most transmission of blackspot is from leaf to leaf, not ground to leaf."
I was interested in your reference for "most". I am sorry if I did not make it clear.
I have no problem with your quote from Horst: ""The fungus overwinters as mycelia in fallen leaves or on infected canes." It does not include a "most".
Now you are limiting your statement with a "If fallen leaves are covered with a new layer of mulch, infection of new growth in spring is going to come primarily from infected canes and old leaves hanging on the plants--carried to the new growth by splashing water."
That is a completely different statement than your original one. I have no problem with that one. If you remove the possibility of one; than, yes, most has to come from the other.
Regarding the effects of different mulches and pH.
In another thread I introduced that a scientific study has shown that horse manure fosters the friendly anti backspot Trichoderma fungi. It is also possible that the soil pH affects the blackspot due to its effect on friendlies.
A cornmeal mulch has been reported to decrease blackspot (see threads in organic roses forum) and it also is known to foster friendlies.
Some tree mulches should also help: "A total of 37 species were found on decaying litter of all 3 tree species. These included .........Trichoderma album Preuss, and T. viride Pers. ex Fr."
Title: "FUNGI ISOLATED FROM DECOMPOSING CONIFER LITTER"
Author: JOHN W. BRANDSBERG
Published in: Mycologia, Vol. 61, No. 2 (Mar. - Apr., 1969), pp. 373-381.
Here is a link that might be useful: link for decomposing conifer litter
Kippy--Yes, I have direct experience with this effect, owing to a change in our winters from zone 6 and sometimes 5 in 1976-85 to consistently zone 7 for the past 25 years. (Most hybrid teas are cane-hardy down to around +5 degrees, or middle zone 7, unless they have suffered defoliation.) When I had to prune severely each year, I was able to manage blackspot on hybrid teas with an organic fungicide (sulfur), and the first spots did not appear until late May or early June. Downside was that the plants were small during the first flush. Nowadays I have 6' plants by this time of year and lots more flowers in the first flush, but I need a more effective fungicide than sulfur if I want to grow a few HTs well.
I wonder if an early spring spraying of the canes with Wilt-Pruf would be useful.
Henry, good idea. I've thought about trying that but never have done so. It would be so hard to tell whether it did any good or not, because I have hardly any duplicate varieties. I wrote to Kira Bowen once with some ideas for trials, I think including this one, but she didn't respond. The idea would be to seal the cane lesions at around pruning time so they release fewer spores to infect the new growth. The film of dormant strength WP is supposed to be good for about 6 weeks. However, the blackspot acervulus generates enough pressure to break through the cuticle, so I don't know that WP would contain it. It has been reported that oil sprays have a partial smothering effect on sporulating acervuli.
Just another comment on the mulch discussion.
If oat straw mulch were superior, I am guessing that it would be the mulch currently recommended by ACES, but it isn't even on the list of mulches currently recommended on a 2012 gardener bulletin.
I went through master gardener training (no great commendation, I understand) under ACES and have never heard oat straw recommended, but pine mulch isusually first on the list . I've read a paper showing that pine straw carries a lot of weed seed, also.
But I do not think that oats are grown in Alabama to any great extent so oat straw as a recommendation to Alabama gardeners would be out of character, I think. Pine trees are common in many sections of Alabama, though.
Does blackspot germinate anywhere except on rose tissue? I think I've read that attempts to germinate it in agar, for example, didn't work.
harborrose, See: link below
Here is a link that might be useful: germination on agar
That's interesting, Dr. Kuska, thank you. Does it germinate w/o an agar source on mulches of different kinds?
Regarding growth w/o an agar source. Apparently the paper always used at least some agar. It is based on a Ph.D. Thesis. Perhaps there would be some information in the Historical Section that would answer your question. This is what the paper states: "The basal-synthetic culture medium was the glucose-asparagine medium of Lilly and Barnett (1951) adjusted to pH 6.0.medium."........... (H.Kuska comment: In one kind of experiment) Cellulose and starch were incorporated into the basal-synthetic medium which was solidified with 2 per cent agar. High-grade filter paper cut to a pulp in a Waring Blendor was used as a cellulose source, and soluble starch was employed at approximately 10 g./l".......... "Growth on cellulose and starch, though not dense, is quite good after six weeks."
There appears to be a pH effect on germination. The following is a quote from the full paper: "The greatest mycelial growth occurred at the lowest pH value at the end of the third week. As the pH started to rise more growth would be expected to take place, but on the contrary, the mycelial dry weights were less at the end of the fifth and sixth weeks."