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Looking for Roses that are TRULY Resistant to Balck Spot

January 31, 2002

Looking for Roses that are TRULY resistant to Black Spot.

I was hoping that you could let me know what indivdual roses are TRULY resistant to black spot. I live in Massachusetts which is zone 6. I started planting Griffith Buck roses three (3) years ago when I read that many of them are resistant to black spot (B.S.).

Some of the Bucks I have planted for there B.S. resistance are: Priarie Sunrise, Paloma Blanca, Sjulin and Pearlie Mae. My favorite is Pearlie Mae as it just keeps blooming with 4,5, and 6 flowers at a time. I have two (2) more on order El Catala and Carefree Beauty, they are both listed as resistant to black spot. As I have planted most of the Buck roses that are listed as black spot resistant I am looking to find some more Gems for my garden, that are highly resistant to black spot.

Also, does anyone know were I can purchase Pippas Song itÂs a Buck thatÂs listed as B.S. resistant but no one seems to have it?

I have heard that the RomanticaÂs are quite disease resistant but being that there are quite a few roses diseases, I was hoping to get some solid first hand experience from other rose growers as to which fair best against black spot.


Abbaye de Clung

Auguste Renoir

Eden Climber

MEIrevolt (were it can be purchased)

MEIvamo (were it can be purchased)

MEIviolin (were it can be purchased)



Of course well out surfing for the RomanticaÂs I came across a hundred others that I would like to have, if anyone can tell me how they hold up to black spot I would really appreciate it. Also, if you have any other suggestions I would welcome them, I am parcial to Tea roses. Thank you.

Orange N Lemons

Living Easy

Fragrant Plum

Princess De Monaco

Gold Medal

Moon Shadow Purple

Centenial Star

Double Delight


Lynn Anderson

Judy Garland


Hiroshimas Children

Jane Pauley

New Zealand



Singing in the rain

Thank you in advance.

Comments (125)

  • littledog

    Seafoam gets my vote for sheer will to live; I bought one in a gallon conatiner on sale at K-mart in August 3 years ago. I kept the poor thing in it's plastic pot, determined to save it until I had my own place. Well, December 31st, 2003 we closed on our home and the dear little thing was finally planted on January 21st, just in time for an ice storm and a week of sub zero temps. I knew I had killed it, and kicked myself for not keeping it inside until spring.

    But HA! Not only was it not dead, it has thrived; lush, shiny foilage, NO disease whatsoever, and even after being stripped completely bare twice last year during a break out by the evil sheep and goats, it has bounced back and is even now smothered in blooms. My only regret is that I didn't think to put it on a treliss and grow it as a climber. Instead, mine is sprawling out in the flowerbed, carpeting the area beneath my bedroom windows with wave after wave of white.

  • well_rooted

    I have sprinkled cornmeal around my roses three times this year. Normally BS is not a problem in our dry climate, but this spring has definitely NOT been dry.

    To my amazement I have very little BS. Showbiz usually defoliates, no matter what the weather, but it still has about 85% of its leaves. BTW I am replacing it anyway.

    I am also thinking....if a baking soda spray is recommended, what about spraying it on the soil too. And I have read of using cider vinegar spray (diluted) as well. Spraying it on the soil may help, and would balance the ph lowering effect of the backing soda. Has anyone tried spraying the soil?

  • chathamcapecod

    I am looking for a disease resistant pink climber which will be top watered and near salt water. It will climb on a picket fence.What is the corn meal baking soda treatment people keep referring to in the thread? Thanks

  • remy_gw

    If you didn't see it yet, the other post titled Cornell Formula gives the recipe for the baking soda treatment.
    The corn meal is a totally separate treatment that I've never done. I really don't know how much people are sprinkling.
    As for the rose, Rugosa type roses are best for salt tolerance. They are very disease tolerant too.

  • jimandanne_mi

    Great thread!

    Someone listed Sexy Rexy as being bs free. I had 50 roses, and Sexy Rexy got black spot and defoliated repeatedly, far worse than any other of the carefully chosen bushes. I loved everything else about that rose, especially the color and shape of the blooms, but would not get it again because of the bs.


  • quitecontrary

    In my no-spray CT yard, the cleanest have been
    #1 - Flower Carpet Scarlet
    This is clean as a whistle, tough, constant bloomer, double scarlet, and cute, cute, cute! Way cuter than Knockout!
    #2 - Crystal Fairy is a heavy bloomer with maybe a spot or two on a lower leaf
    #3 - Bonica gets a few spots, but is a heavy bloomer and never dropped any significant amount of foliage

    The above 3 are all new this year. When I was in Florida, I grew Sunflare for at least 5 years without spray and without any noticeable disease.


  • constance22


    Try Cl. New Dawn.

  • whitejade

    Baby Love has done extremely well for me. It also puts out non-stop flowers and the fragrance fills the air all around.

    I noticed the original post was in '02 and by now in '07 we all probably know how well all the Knockouts do with resistance to BS.

    I agree with the Austins being BS magnets and I will not plant anymore of those. I am finding that some of my mini-flora roses are really BS resistant. Pacific Serenade and Sweet Arlene are 2 that come to mind.

    The leaves are a clue in my experience, just as someone else mentioned ...the shinier, medium to darker leaves that are of heavier substance seem to do the best.

  • geo_7a

    Recommendations for Kordes roses (blackspot resistance?) on the east coast, mid-atlantic?

    Trying Dornroschen, Sunsprite, Folklore, Westerland (and sport Autumn Sunset) in the Spring.

  • none_domain_com

    Here in TN,
    Knockout is great...sure it gets it from Carefree Beauty...(my Knockout seedlings are quite resistent but less so than Knockout itself...but they're yellows).
    Fairy is liveable and so is Ballerina (...but they both have it some...think my Ballerina is virused though).
    Robin Hood somewhat better than the above two (...so it comes in second below Knockout...although there is some minor spottage...not enough to notice).
    Carefree Delight does OK but some BS.
    Carefree Wonder seems to be good so far.
    Sunsprite has it bad for me....(carefree beauty x sunsprite = one of Buck's 'Prairie' roses...thinking Prairie Song...maybe Singer...in fact quite a few BS resistent roses have Carefree Beauty as their seed parent...I'm playing with Sunsprite as a parent anyways...like Knockout seedlings x sunsprite).
    New Dawn some BS but vigorous anyway.
    Graham Thomas has it bad.
    Sombreuil is quite healthy...in fact I may rate it up there with Knockout and Robin Hood.
    Peace isn't entirely BS free ...but almost... it's quite healthy here (although I've heard others complain)...still rate it extremely high...in fact it's a 'must have' for everyone in my book.
    ...Of course all rugosas are healthy....and smell good too.

    I'm not going to list all those that DO have a problem here (I've only contradicted some of those that were mentioned above as being BS free above)

    Okiez7's list seems to be pretty good. I read in 'The Ultimate Rose Book' that Chanelle is BS free also which is not said of any other rose in the book that I noticed. I'm wanting it but hate paying like $36 for a small band of it....anyone know of a source?

  • geo_7a

    Does anyone in the U.S. grow (own root) the rose "Especially for You" and, if so, from where did you get it?

    Supposedly is a yellow very fragrant rose with superior disease resistance, but apparently apart from Hortico (and thus I guess it is grafted) it does not appear to be available on this continent.

  • craftlady07

    I had fun reading this post in it's entirety and seeing that it's lasted this long I figured it might be worth resurrecting again :)

    I am extremely new to roses and looking to buy my first shrub(s). I am in Eastern PA, zone 5b, I know BS and J. beetles will be my nemisis when it comes to growing roses.
    From what I'm told in our area knockout roses perform the best even though they are JB magnets (from what I'm reading here). So I'm on the fence about getting one.

    I LOVE DAs but I don't think I will try them as I'd like the roses to be as maintenance free as possible.

    I'm seriously considering Iceberg, Living Easy and Carefree sunshine to plant together in full sun, away from the house where I feel they will get good air flow as the backyard is fairly open.
    I REALLY love Red roses and would like to add one in addition to or instead of these....any thoughts/suggestions?
    Thanks in advance!

  • brandyray

    Craftlady, I just happened on this thread. Mine are all babies but I chose them after reading recommendations on the OGR forum. Some red ones that are recommended: Valentine, Deep Secret, Red Cascade (mini climber), Louis Phillipe, Griff's Red, Chevy Chase (climber), Cramoisi Superieur, Home Run, Brave Heart, Raven, Illusion, Royal William, Chrysler Imperial, Mirandy, Alec's Red, Traviata, Dusky Maiden (single), Fields of the Wood (climber), Dame de Coeur (single), Altissimo (single), Tradescant, and Taboo. Of course, it does matter where you are as to how much black spot pressure there is. Good luck! Brandy

  • plan9fromposhmadison

    Aside from species and near species (Cherokee Rose, Fortuniana, Banksia, Rosa Soulieana,Fortune's Double Yellow), I've only grown one that was totally without Blackspot. That one is Autumn Sunset. I planted 6 own-root plants in August of '08, (highly stressful in our heat) and have yet to see the first black-spotted leaf.

    These are not far from a bed of 9 Griffith Buck Serendipity roses that are blackspot magnets (not a serious threat, even though it defoliates them, somewhat), and a long border that includes 9 blackspotty Don Juans, and 10 marginally blackspotty New Dawns. So the spores are there, but the Autumn Sunsets are shaking them off. I see a lot of R. Multiflora in Autumn Sunset.

  • mairenn

    In 15 years in Georgia I have never seen blackspot on a Cherokee or a Lady Banks. (or, sad to say, a wild Multiflora!) I have rarely seen any on a China, including Mutabilis.

    Until this year, I have never sprayed or fertilized anything. I have a Climbing Old Blush that is about 3 years old with maybe 2 spots on it. Climbing Cecile Brunner 4 years old has a little, but not much. Climbing Josephs' Coat 5 years old gets it badly. Patio minis lasted almost 5 years before it killed them. My 5 year old Cherokee is completely disease free. Four-year old Fairies in containers got powdery mildew every spring, but never got blackspot until this year, and defoliated completely.

    The good news: Powdered milk spray does in fact stop powdery mildew. Baking soda spray (put on the new growth in desperation after the first defoliation) seems to have utterly prevented a repeat outbreak of blackspot. This is the first year I've tried it, and here's hoping it keeps working.

    Another thing I've noticed: I used oak leaf for mulch in some beds and not in others, and it seems to make the blackspot worse.

  • Zyperiris

    I had lots of BS with my romanticas. So far for me Livin Easy is great and Julia Child

  • ebmcconne

    I tend to agree with others who have stated that one cannot find a truly black-spot resistant rose. I believe that it depends on so many factors-the health of the plant, how it was planted, soil, air circulation, humidity, etc. I am new to roses; this is only my second year, but I have not had black spot AT ALL(knock on wood). I live in humid zone 5 and am pretty bad about packing in plants together so the air circulation is probably pretty bad. I think what works for me is prevention, good soil, and good planting. I spray my roses once every week or 2 with neem oil, sulfur, bayer, or dishsoap. Be sure to spray in the evening so that the leaves do not burn. I sprinkle cayenne pepper around and on the roses every couple weeks to prevent pests. I spray the roses with the hose about once a week to rid them of any mites. I deadhead and remove leaves that have been chewed on or show other damage almost everyday. I am sure to dig a huge hole when I plant and add compost, epsom salts, and bone meal. I have read mixed reviews about epsom salts, but it is inexpensive and many critters do not like salt so what could it hurt even if it does little to fertilize the plant? After planting, I add mulch around the roses. I have had some minor problems with mites, aphids, and japanese beetles, but the regular spraying takes care of it. This spring I pruned them back pretty far.
    I really do not find the spraying to be that much of a chore. I might spend 15 minutes spraying 6 bushes. Most of us rose growers are the type that love to fuss over a plant and probably have some control/OCD issues so it would be difficult for us to not spray, deadhead, etc and generally obsess over our plants. I planted these flowers to enjoy them so of course I am going to look at them everyday, and its natural to deadhead or spray when I do so. Since I rotate different products-some of them homemade-I do not find the cost of spraying to be that outrageous. Last year I might have spent $10 on spray. I do not really use any other kind of fertilizers other than compost and epsom salts; I am afraid of them and am searching for some organic fertilizer. I try to be as organic as possible. I think if your soil is bad or you don't deadhead or remove damaged parts of the plant, then you will get pests and disease. I will probably try the cornmeal idea, which I have never heard of; it is inexpensive and won't hurt the plant even if it doesn't work. I will also add the baking soda into my rotation of products. By the way, the rose bushes that I have are Golden Showers (climber, bought bareroot), SunFlare (floribunda, bought plant at big box store), Iceberg (floribunda, plant, big box store), Blue Girl (hybrid tea, bareroot), Hot Cocoa (floribunda, big box store), Arizona (grandiflora, big box), First Prize (hybrid tea, big box store). I know many people thumb their nose at big box stores, but I have seen as many raggedy plants at local nurseries as the big box stores. I do not like to invest alot of money in a plant especially since I am a new gardener; the most I have spent on a rose bush is $12 and most of them were $3-5. Losing $3 is way more reasonable to me than $30, $50. If I had to spray 100 bushes, I probably wouldn't want to do it but 6 bushes takes no time at all. And I have had no diseases-no powdery mildew, no blackspot, no horrible pest infestations, no rust. I will be curious to see if this holds true the rest of the summer and next year and will continue to report on the health of my roses. I have included some pictures of my bushes. You can probably see the sprinkling of cayenne pepper on some of them!!
    a href="http://s380.photobucket.com/albums/oo245/eurekafly6/?action=view¤t=012.jpg"; target="_blank">

  • dublinbay z6 (KS)

    ebmcconne, congratulations on your lovely roses.

    If you are feeling rather worn-out from your busy garden routine, you could throw out all the sprays and just use the Bayer once every 3 or 4 weeks--and get the same results.

    Of course, Bayer is not organic, but it is effective. On the other hand, if you truly want to go organic, throw out the Bayer and invest in some of the disease-resistant roses mentioned in this thread.

    Some of my more disease resistant roses are Austin's Mayflower and Austin's Mortimer Sackler and Austin's Pretty Jessica. Other Austin's that aren't quite as resistant but not too bad: Molineux and Queen of Sweden. Some other resistant roses are Elina (HT), Eutin (FL), Lambert Closse (Canadian Explorer), Home Run (shrub descendent of Knock Out?), and climbers Dublin Bay, Viking Queen, and Sombreuil.


  • mmayerct

    BS report from CT:
    I grown two varieties of Buck Roses, plus New Dawn and Knockout. I wish i could state something different, but none are BS resistant for me. The Buck roses are planted in full sun in 4 raised beds, 2 per bed with lots of space. I decided to go natural last year. I pruned my Buck roses about 1/3 of the way down and pruned out some interior branches to improve circulation. I started with baking soda (diluted with water and a bit of dishsoap and had moderate success. Occasionally I would switch to vinegar, water and dish soap. When- and only when- i sprayed once a week, it kept the BS somewhat at bay. When i slacked off for even a week, trouble began. There is no easy answer here but I'm not ready to give up. This year I'll try the cornmeal. Nothing to lose! My New Dawn is not in 100% sun and that may be the problem, but I find it no better with BS than my Bucks. Wish I had better news!

  • serenasyh

    Argh, I hate Bayer. I will not buy any products with Bayer because they produce the insecticide Sevin which is deadly to the honeybees. I have boycotted them and have put them on my bad list because of the Sevin and other toxic pesticides that they produce. I agree that their fungicide is popular, but so long as they keep manufacturing Sevin....

    A great rose is CORNELIA!!!!

    Viking Queen, Crepuscule and Belinda's Dream are other really great roses for BS resistance.

    Mrs. B.R. Cant was also pristine, and I loved this rose, but alas, it could not survive my zone 5 winter.

    I have very high BS pressure in my locale but I refuse to use fungicides. I used to have good success with Greencure but last year we had non-stop rains and flooding and I have found when this happens to never ever spray ANYTHING on one's leaves. It is critical that if you have tons of moisture, unending rains, the roses do best when left completely alone. It is crucial that rose leaves must be able to dry out. My biggest ally against BS is hot blazing sun and no rains. In 2009, I had a terrific year. My roses remained pristine because we didn't used to get all this non-stop rain.

    I use Gardenville sea tea to so that my roses can refoliate very quickly. The strongest continue to survive and they bloom like crazy so I just ignore the BS and enjoy the blooms, lol! It keeps me sane that way, haha! I refuse to grow anything besides Hybrid teas, Antiques (not to be mixed up with Austins), and hopefully someday a Rugosa. HTs are very susceptible to BS, but I love them and they are STAYING in my garden! I'm trying the cornmeal test too for 2011, lol!

  • gen6tex

    I moved into a house four years ago with a hybrid tea and what looks like one of the newer "English" landscape roses already planted in the yard. In rainier years they are covered with black spot. I don't spray or use chemicals of any kind. They always look skanky.

    I added four old polyanthas (White Pet) to the yard in the first year. I thought I would have to remove the two already there to keep my "new" old roses healthy. I decided to wait and see what happens. I'm happy to report that even when the lesser plants are infested, the polyanthas are virtually black spot free as well as free of pests and other diseases.

    I might add that I live in central Texas where we are experiencing a history-making drought. I haven't watered them once this summer and they are only now looking stressed. They are planted on the north side of the house alongside a porch. I think this helped.

    I highly recommend the old roses. I wouldn't grow anything else.

  • friedabyler

    Dutchess de Brabant has been a wonderful rose for me, blooming her heart out in spite of our Mid Atlantic heat and HIGH humidity. I've never seen black spot on her, in spite of the fact that the Don Juan nearby had a touch of it until I got out the neem spray. [great stuff, if you must spray, btw]

  • hummersteve

    Last year for the first time I decided to try some roses and since Lowes had some cheapies on sale I decided to try them . Im afraid I lost the label. But I know they are not knockouts. I had set my mind against buying those. I got one red and one yellow and gave them the same mix and a good dose of composted manure. The red one did little but the yellow one turned into a champion, seeming to burst into bloom from day one and never stopping and on top of that I experienced no insect or leaf problems. I so loved this plant that Im trying to propagate cuttings from this one. Another reason of proof they are not knockouts is they do not deadhead which is what I understand they do. Because I do usually have aphids on my other plants I do use the organic neem oil in my spray can and also sprayed the roses. Not too bad for my first try at roses.

  • rosesr4me

    Second for Belinda's Dream. I live near the coast in Florida...almost all roses I have grown in the past 16 years get blackspot here. But I have never had to spray my 10 year old Belinda's Dream. From what I understand, Walt Disney World calls Belinda's Dream THE rose of Florida.

  • cambel

    Barbara Streisand and New Zealand!

    Ok, Just kidding.

    I have had good luck with both Devonsensis and most of the David Austin Roses.

  • emese

    I went to Home Depot to look at the Knock Out roses...totally disappointing! I have seen much better ground cover roses. Of course, this is a very wet area, lots of rain, so perhaps that is why these roses were covered in BS. I guess KnockOuts were bred with California weather in mind.

  • jim1961 Zone 6a Central Pa.

    I'm guessing your area has a strain of BS that knockouts
    may not be resistant to...???

    Knockouts are very disease resistant here and are resistant to BS in a lot of other locations throughout the

  • dani33

    I am looking for two climbing roses...one for over an arbor in the entry to my yard and one is for a pergola in my yard. I am in z6 (MA) and I am looking for as disease resistant a rose as I can get cuz I won't be spraying them. I really love Eden, but I was told she isn't a repeat bloomer and can be susceptible to rust (or some other nasty). Stinks cuz I love that kind of rose. I was also looking a Zephrine Dourhin cuz she is supposed to be thornless, but I think she may get too big. I like Jasmina & Renae also. I just would like a rose that can grow well w/o spraying and that flowers a lot without having crazy thorns or trying to eat my arbor. Should I rub a lamp? Lol.
    Also, I have been scouring for Pretty Jessica and only found her "banded". Iama newbie & have no idea what that means. Anyone have an idea? Ty in advance

  • strawchicago

    Hi Dani33: I post below a picture of "banded" rose so you'll see how big it is. A band is a narrow pot about 6" high, decent long-root that will get wider once transferred in a bigger pot.

    Annie L. McDowell rose is a climber with zero thorns (only a few tiny prickles on the back of a few leaves). It smells like heaven (lilac-lavender scent). It's NOT appropriate for pergola, since it's not aggressive enough, but if you are in a warm zone, it will eventually go up your arbor. It's the MOST DISEASE-RESISTANT climber that you can get.

    Annie L. McDowell is the improved-child of Renae, but the blooms are prettier & more doubled than Renae. Since Annie flowers at the expense of growth, it's a slow-growing one, might not be robust enough for zone 6 (MA). Both Annie and Renae repeat blooms well. My Annie in zone 5a is a tiny 2' x 2' bush, due to winter-kill. But if your soil is acidic, Annie is more aggressive. Annie is a wimp in warm & alkaline CA.

    Columbian climber rose, almost thornless, is VERY IMPRESSIVE from the pics I have seen growing up a pergola. That one grows well for Daisy in Crete, Mediterranean climate, with sandy alkaline soil.

    Jasmina is a Kordes rose from Germany so it's more disease-resistant, that would be appropriate for the pergola. The most impressive sight of a rose growing over a an arch is a red "Blaze climber". The stems are thin and can easily be trained over the arch, Annie L. Dowell stems are too thick & rigid, hard to train. No one can beat Blaze climber (tons of blooms, but has thorns). "Stairway to Heaven", a red climber is listed in catalog as Very disease-resistant.

    People rave about Cecile Brunner, with light pink, is robust enough for pergola. It's low-thorn, a delight since 1894. Burlington Roses in CA sells band-size for $11, also gallon-size of Cecile Brunner. Everyone like Cecile Brunner, but few like Zeph. Drouhin.

    Zeph. Drouhin is a disease-fest, plus blooms once or twice a year, I won't even consider that one, although it's thornless. Pretty Jessica is almost thornless, slow-to-establish. Sonia Rykiel is a more rewarding version, insanely fragrant that my kid wanted to eat the blooms. Some prickles, not bad, and flowers easily. Sonia Rykiel is my top rose, so with Kittymoonbeam ... she's a large rose grower in CA. Kitty once stated that if she has to create the most perfect rose, it would be Sonia Rykiel, and I agree. Sonia Rykiel is sold as a gallon at Roses Unlimited in South Carolina.

    I'll post picts of a "banded" rose, bought for $10 each during Heirloom 1/2 price sale in July. The link below is priceless, it's has pictures of no-spray & healthy roses recommended from Pinterest.

  • lelamsk

    I remember when the Knockout roses first came out. They were everywhere. I walked into a well know nursery and told them that they should treat the blackspot that was covering their knockout roses.
    Now maybe they have gotten better, but i kind of gave up on them.
    Blackspot resistant
    Lady Banks (l once bloomer but gorgeous)
    Cecile Brunner
    Soaring Flight (a wonderful constant blooming rambler from" Heirloom Roses". http://www.heirloomroses.com/soaring-flight.html

    Playboy does pretty well and can take a shady spot.
    Seven Sisters
    William Baffin
    Darlow Enigma
    Night Owl is a great short climber/bush that does well in shady area and has small amount easy to grow blackspot.

    (America, Zepherin Droughin, are blackspot and mildew magnets)

  • Mas_Loves_Roses

    Straw, you made me laugh with your post about your kid wanting to eat the bloom! I love reading that you so highly recommend Sonia Rykiel as this is one of the roses that I ordered along with Poseidon from Roses Unlimited for next spring! Fingers crossed that I get it! :)

  • jim1961 Zone 6a Central Pa.

    I'm still in the process of trying to find very disease resistant roses for our area.
    Now their are some roses that may do well here but because I do not like the bloom, color, size of bush or whatever I have not tried them yet.

    But so far the best two roses that stay the most disease free are Double Knockout and Carefee Sunshine...

  • strawchicago

    Hi Jim: You have a nice camera .. very sharp details. It's raining non-stop here for 3 days, very humid weather. Potassium hardly move where it's applied ... a 3 mobility, rather than a 10 like Nitrogen. Thus it's best as soluble, or burying banana peels at the bottom of the hole.

    The roses that I gave soluble potassium (sulfate of potash) have very little black spots. They are: Angel Face, Comte de Chambord, and Radio Times. Even Gruss an Teplitz has only 2 leaves with blackspots not bad. Folks reported those as disease-prone.

    Below picture is Comte de Chambord, a rose known for blackspot-prone. I gave it sulfate of potash, picture taken after 3 days of rain. I dumped a bucket filled with 5 inch. of rain, to test the drainage. Zero black spots on that rose:

  • strawchicago

    Below rose is Gruss an Teplitz, the parent of Dr. Huey (the rootstock that most roses are grafted on). Gruss is known as disease-fest. Last year in perfect potting soil, Gruss broke out in mildew, plus aphids, despite adequate calcium & potassium. I planted Gruss on a sunny hill, Gruss' mildew persisted.

    I gave Gruss corn-meal, the mildew disappear. So I dug Gruss up, put 2-cups of cracked-corn in the hole, plus gypsum & sulfate of potash. He behaved during our dry spell (no mildew), also in our current wet spell (only 2 leaves of black spots). Picture of Gruss an Teplitz rose below was taken June 19, after 3 days of non-stop rain:

  • strawchicago

    For disease-resistant roses that OTHER FOLKS report, besides me (with alkaline clay), Excellenz von Schubert is always clean. Seaweed in CA posted her EVS in full-sun with tons of blooms. My EVS is in 4-hours of weak morning sun, less blooms, but always healthy:

  • strawchicago

    All my roses are own-root, except for Knock-outs.
    Another disease-resistant rose is Christopher Marlowe, reported healthy in CA, as well as in my Chicagoland alkaline clay. Picture is taken June 19, after 3-days of rain, Christopher Marlowe rose gets only 4 hours of morning sun:

  • strawchicago

    Another rose which is always clean for the past 4 years is my OWN-ROOT Pat Austin. She gets 4 hours of morning sun, picture taken June 19, after 3-days of rain, and very humid weather:

  • jim1961 Zone 6a Central Pa.

    Thanks for the info Straw! I only grow own-root. I have never even grown a grafted rose yet.

    "soluble potassium (sulfate of potash)"
    What product name did you use Straw? Thanks

  • strawchicago

    Hi Jim: It's always good to hear from you .. you are one of the nicest people in the other forums. I use sulfate of potash (potassium sulfate), SOLUBLE powder form, NPK 0-0-50 from Kelp4Less ... it's $8 a lb., free shipping. I dilute with water 1st, like 1 teaspoon per 2 gallons, pour at plant's base, before a heavy rain. The rain will work that down to the root-zone. I double-the dose for black-spot prone roses.

    The potassium chloride, or muriate of potash in fertilizers at stores are MUCH HIGHER IN SALT, at 116.2 salt index, versus LOWER salt sulfate of potash at 43. So it's worth ordering on-line. Sulfate of potash is also low in chloride, and roses are sensitive to chloride (break out in rust).

    I haven't decided yet to use granular sulfate of potash for the planting hole, or to use high potassium & high iron red lava rocks ... the crushed red-lava-rock can also be ordered on-line. That might be best for my heavy clay & alkaline soil.

    Below is Angel Face rose in my garden, I put gypsum in the planting hole, and watered it with SOLUBLE sulfate of potash. Since sulfate of potash stay put where applied (NOT mobile like nitrogen), even if the top surface is tested OK with applied fertilizers, the bottom hole may still be deficient.

    I don't spray in my garden. Sulfate of potash is a natural mineral. Here's an excerpt from link below: "Potassium occurs abundantly in nature, being the 7th most common element in the earths crust. Some clay minerals which are associated with heavy soils are rich sources of potassium. They contain as much as 17% of K.

    Potash bearing rock deposits occur in many regions of the world. They are derived from the minerals in ancient seas dried up millions of years ago. Fertiliser potash is mostly derived from these potash rocks."


  • jim1961 Zone 6a Central Pa.

    Cool Straw for the great info... Thank You!

  • strawchicago

    Hi Jim: Mas mentioned that she's applying silica ... known to strengthen cell-wall. I checked on potassium and disease-prevention, and found this in Wikipedia, "In agriculture, some cultivars are more efficient at K uptake due to genetic variations, and often these plants have increased disease resistance.[1] The mechanisms include a decreased cell permeability and decreased susceptibility to tissue penetration. Silica, which is accumulated in greater quantities when adequate potassium is present, is incorporated into cell walls, strengthening the epidermal layer which functions as a physical barrier to pathogens. Potassium has also been implicated to have a role in the proper thickening of cell walls."


    **** From Straw: I notice that my disease-resistant roses: Basyes Blueberry, Excellenz von Schubert, Knock-outs, Kordes Flower Carpet, Annie L. McDowell, Marie Pavie, Bolero, Christopher Marlowe, Frederic Mistral, Old Port, Lilian Austin, and Nahema have THICKER LEAVES than flimsy Gruss an Teplitz' leaves.

    The disease-resistant own-roots are more efficient in getting potassium from the soil, than Dr. Huey's parent, Gruss an Teplitz. I notice that when I bring down the pH of my alkaline tap water through a bit of vinegar, ... the leaves of Sweet Promise rose became thinner, and more wilting in hot sun.

    So I checked on that, and a few University Extension mentioned that as the pH drops, levels of calcium and potassium are less available. There's the misconception that the pH has to be slightly acidic for roses to bloom best ... that's NOT true. The best tons-of-blooms in HMF are from sandy alkaline gardens, such as of Kitty Belendez in CA, she uses a soluble fertilizer mix, including kelp meal. Seaweed has alkaline clay soil, and she gets tons of blooms with soluble fertilizer.

    Alkaline soil pH doesn't matter, since plants can do acid-phosphatase (secreting acids to utilize phosphorus in soil). Dr. Huey root-stock is good in acid-phosphatase for blooming, but lousy in getting potassium from the soil.

    Here's an excerpt from eHow: "Potassium levels increase with higher pH levels, so acidic soils, which have lower pH levels, tend to have less potassium content than alkaline soils. According to professor Linda Chalker-Scott, potassium levels are particularly low in sandy acidic soils.

    Amending Your Soil: If your soil has low pH and potassium levels, you should apply lime to increase soil pH. For potassium-deficient soils that are not acidic, fertilizers such as potassium sulfate (sulfate of potash) may be more appropriate."

    *** From Straw: below is Annie L. McDowell, zero diseases for the past 2 years, that rose has VERY THICK leaves. I put gypsum in the planting hole & use soluble sulfate of potash. Picture taken June 19, after 3-days of rain & humid weather:

  • jim1961 Zone 6a Central Pa.

    I'm going to get a new soil test done soon. Any recommendations on a good place that does those tests Straw?

    My last soil test showed levels of potassium were ok...
    PH 6.6-6.7

    This time I'm going down at least 8-12 inches for soil...

  • jim1961 Zone 6a Central Pa.

    Addition to my last post. I am not familiar with silica...
    I need to research that compound.
    Where does a person get a source of silica?

  • strawchicago

    Hi Jim: There's only one research "Potassium Silicate decreased black spots in roses" ... if you search Potassium Silicate in this forum, you'll find it. Silicate is EVERYWHERE in nature, esp. in sand ... deficiency is rare.

    I got my soil tested by EarthCo. for $20, which I got my pH of 7.7, deficient in potassium, phosphorus, and barely adequate in calcium (I'm next to a limestone quarry!).

    Do-it-yourself red-cabbage pH test for $1.50 ($1 of distilled water, plus 50 cents of red-cabbage leaves): that's even better than a professional soil-test. Why? You can test as many samples as possible from your garden, and treat accordingly.

    Below is a link that has a chart which show which nutrients are most deficient at what pH. However, the most accurate test is WATCHING each rose for any nutritional deficiency. Each rose has its own particular needs, depending on the spot where planted, and its genetic-make-up.

  • jim1961 Zone 6a Central Pa.

    That last link you posted about how to identify nutritional deficiencies based on PH is not working Straw...

    And thank you again for the info you provied Straw! :)

  • strawchicago

    THANK YOU, Jim, for notifying me that the link doesn't work. It's a VERY SLOW loading link from Australia. So I deleted that, and replaced with a better link from Cornell University, it talks about boron deficiency, but if you SCROLL-DOWN, it has an excellent chart that detail what nutrients are less available at what pH level. See below, I also changed the previous link to Cornell University's link:

  • jim1961 Zone 6a Central Pa.

    Thanks for the link Straw!

  • strawchicago

    Re-post the link to nutrients deficiency Chart from Cornell (got lost through the change from Gardenweb to Houzz). Scroll way down past boron-deficiency, and you'll see the chart on what nutrients are less at what soil pH.


    If someone get a soil test, what's in excess can influence what's available. Potassium, phosphorus, calcium, and magnesium all compete for the same absorption, so if someone's soil is high in phosphorus, plants will soak that up, creating a deficiency of potassium and calcium (both are necessary for disease-prevention).

    And for my alkaline heavy clay tested very high in magnesium, my soil test recommends giving my plants calcium (gypsum), potassium, and phosphorus. Why? Excess magnesium makes my clay heavy, and prevents absorption of other minerals.

    I always wonder why Khalid's roses grafted on Centifolia don't show blackspots, and my Centifolia rose Le Nia Rias never have blackspot for 4 years either, until I found the below info. from Cornell University:


    In general, the Rosa rugosa hybrids and old garden roses like gallicas, damasks, and centrifolias have good resistance. Rugosas cannot tolerate some chemical sprays, so should be kept clean with pruning rather than reliance on pesticides. Table 1 contains a brief list of roses with superior disease resistance.
    Table 1: List of Roses with Superior Disease ResistanceHybrid Teas Grandifloras FloribundasShrubsClimbers

    Ivory Tower
    Jardins de Bagatelle
    Pink Peace
    Precious Platinum
    Touch of Class Love
    Queen Elizabeth Betty Prior
    Gene Boerner
    Passionate Kisses
    Trumpeter Ballerina
    Carefree Wonder
    Knock Out series
    Meidiland series New Dawn


    **** I disagree with the above list: My Pink Peace as grafted on Dr. Huey is blackspot fest, until I dug it up to put 4 cups of lime in the planting hole, and it's clean ever since. My 2nd Pink Peace as own-root was healthy (died over zone 5a winter), I don't spray whatsoever, not even organic stuff.

    The above list should specify as if they are own-root or grafted on what rootstock? Plus the list should specify what type of soil they are healthy in. Too bad zero info. is given, thus it's not applicable to different soil and climate.

  • Khalid Waleed (zone 9b Isb)

    Straw: You are right. Very few of my roses grafted on centifolia get black spot.They do get some blackspot when roses are placed very close and there is little air circulation or when the soil pH remains acidic for long time. I have been taking care of these aspects this year and there have been zero blackspot cases out of 130 odd bushes, though there have been around 10 mildew cases.

    BTW, good to be posting in a 14 years old thread... I like it

    best regards

  • strawchicago

    Khalid: Yes, the many pics you posted of your 130 roses in pots & in the ground are 100% healthy & grafted on Centifolia-rootstock. I never see any blackspot, and very few cases of mildew when you had tons of rain.

    Thanks for letting me know that this thread is 14 years old, whatever info. we exchange will be passed to future generations .. that's great !!

    Centifolia-rootstock can take wetness better than Dr.Huey .. Dr.Huey likes it fast-drainage & alkaline. My Centifolia Le NIa Rias is right under a rainspout which dumps tons of water on, still 100% healthy .. and I didn't have to dig down to 2.5 feet for drainage like own-roots or Dr.Huey-rootstock. Zero mildew nor blackspot on that Centifolia for the past 4 years since my soil pH is very alkaline at 7.7.

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