This was a clear concise reminder of what I need to do over the next few weeks. Thanks

Fairly standard and good advice generally until I got to the spraying part. I thought we were out of the dark ages and more environmentally conscious than that. You just need to choose the right roses for your area, and don't assume that hybrid teas and floribundas are the only roses in existence. There are extremely disease-resistant roses for every climate zone (tea roses, Griffith Buck roses, rugosas to name a few) and it's just a matter of educating yourself. This forum and others on the Garden Web can be very helpful in aiding you in choosing the right roses and caring for them organically. I'm sorry if I've strayed off the subject somewhat, but I was rather upset by the idea that every rose gardener had to use toxins to have nice roses. Nothing could be further from the truth.

Ingrid

I have a "no toxin" garden. I spray with organics. Maybe a touch of sulphur or soap mixture.

Good for you Susan. I hope that more people will follow your example. There does seem to be more awareness nowadays but I'm still distressed by the number of people on the rose forums who declare that they spray every two weeks

Ingrid

The writer is a Master Gardener, not a Consulting Rosarian. I'm a Consulting (Master) Rosarian and do not recommend spraying. I promote allowing the garden to become balanced with predatory insects and birds for insect control. Planting cover for nesting birds helps keep insects down as they feed them to their young. Once a balance is established the gardener has to learn to ignore the occassional insect damage.
My thought is "Bugs got to eat too!"

Maybe in SoCal you don't need to spray, but almost every type of rose gets blackspot in my yard. So I spray regularly. And yes, you need to start the spraying as soon as the roses leaf out or they will get blackspot and likely have it all summer long. Sorry, just a fact of life in most rose gardens.

karl_bapst_rosenut, concerning the author's credentials, the following is a quote from the article: "Carolyn Alexander is a Cooperative Extension Volunteer Master Gardener and Consulting Rosarian for the American Rose Society."

buford, you stated your experience in your area (I assume with the type of roses that you choose to grow), fine, no problem with that; but then you end with a general statement "most rose gardens". ????????????????

Yes, most people outside of the West Coast have issues with black spot. And I have all types of roses, even teas get black spot, not just HTs.

In some Eastern areas, it is quite hard to find repeating roses (other than rugosas) that will stay well-foliated through the season without fungicide, although organic fungicide such as sulfur can be effective enough. There is a continuum from areas where spot diseases hardly exist to areas where the overwhelming majority of roses have fairly severe to very severe problems. And roses that seem for years to be resistant sometimes contract a strain of blackspot that defoliates them.

It depends on where you live and how much you are willing to tolerate diseased plants.

In my area, most reapeat bloomoing roses will get BS. And by that I mean not a few cosmetic spots, but 80-100% leaf loss. So your have only four choices:
1. grow Knock Outs (even Carefree Sunshine and Home run will get BS)
2. grow once bloomers( my choice mostly)
3. grow naked roses
4. spray
This is reality.
Olga

olga, you did not say where your area is (except for zone 6b). I notice that you grow Illusion. Would you include it in your choice 1?

http://www.helpmefind.com/rose/l.php?l=2.3368&tab=32

Here is a link that might be useful: Illusion comments including Atlanta, GA

I am in Maryland and my list of roses is not updated.
In my choice 1 I would include Darlow's Enigma and Quadra.
I grow roses for long time. I am constantly looking for resistant roses. Every time there is some decent hint that the rose is BS resistant. I jump on it. Illusion was one of such jumps. I still grow it. It was not so bad for a year or two, but later get worse and now it gets at least 75% defoliation, which is unnaceptable for me.
I tried all these supposed to be resistant in other areas roses like Mayflower, Baby Love, Westerland, Leaving Easy, Home Run, multiple Carefrees (Beauty, Wonder, etc), Bucks (there are 3-4 that will keep 30-50% leaves), Teas, Chinas, Hybrid Musks, new and old Kordes roses and many others, it was dissapointment in most cases. Laguna (Kordes is quite BS resistant but gets Cercospora)
I have good soil, full sun and provide good water during dry months. It is not me or my culture practice. I know several people in MD who grow roses and they have similar experience. Some of them accept more BS. 50-75% leaf loss is OK for them ,if rose is still flowering, but I saw their gardens and it is not acceptable for me.
I have a lot of healthy roses.
Early oriental yellows (with the exception of Harrison Yellow) are very healthy here, I have hugonis, Canary Bird, Primula and Cantabrigiensis now.
Several Albas ( I tried all available albas over the years) are good (Semiplena, Maxima, Konigin von Danemark (sometimes gets BS))
Approx 1/3 of gallicas is healthy.
Some ramblers, somespecies, some spinosissimas, Ispahan, couple Centifolias and Mosses.
I love my garden, but there are less and less repeat bloomers every year.

Olga

Blackspot is still a mystery to me. LOL. I've seen weird things. My friend had 3 roses which were all the same rose. 2 were planted in a raised bed and 1 planted right outside the raised bed in the ground.
All were close to each other, almost touching.
The 2 roses in the raised bed had mostly soil around the base and scattered pieces of older larger pieces of mulch. The rose in the ground had grass growing under it, which he mows under it. The 2 in the raised bed had 90% leaf loss from Blackspot. The rose in the ground with grass under it had NO blackspot what-so-ever. He does NOT spray.
So strange! LOL.
I can grow Precious Platinum here with no blackspot problems. No spraying. Yet, my friend 3 miles away has 80% leaf loss on Precious Platinum with no spraying.

I forgot to add rugosas. Some original ones (not heavy hybrids), Alba, Rubra, Roseraie de l'Ha, Polareis are mostly healty.
Olga

Olga, have you tried any of the Kordes Fairy Tale or Vigorosa roses? Cinderella Fairy Tale and Brothers Grimm Fairy Tale in particular. If so, how did they perform for you in BS terms?

Yes, I did try some of them. I am mostly interested in fragrant roses. I tried Floral, Lion, and Caramel Fairy Tale roses. The healthiest of these three is Floral FT for me, it does get BS, but can be grown (and look good) with less frequent spraing. I gave them away to my friend, who tolerates more BS then me. I didn't try Cinderella yet. Thinking about trying it.
One other Kordes that is not bad interms of BS resistance is Aloha Hawaii.
As for Brothers Grimm Fairy Tale, I didn't try them myself, because I saw couple of them in other Maryland garden and they were deseased. Don't remember now which two in particular. I know Connie grows them in VA (Hartwood Roses), she sprays, but as I understand not so regularly, would be interesting to ask how they do for her.
Olga

I'm surprised we still refer to 'organic' as a safe alternative given that both strychnine and arsenic are 'organic'. I try to maintain a no-spray garden... including kitchen chemistry. If it's effective, it's toxic to something. I like the bug-eat-bug approach and a clean pair of pruning shears.

Thanks Olga. I asked as many of the Fairy Tale and the Vigorosa roses are virtually clean and immune to the strains of BS up here. Obviously you have a lot more BS pressure than I, so I was curious how they performed for you. I appreciate the response.

Organic gardeners refer to organic as having a different meaning than the word "organic" as in "organic chemisrty". (An aside, in chemistry Arsenic would be classified as "inorganic" not organic.)

Of course all definitions of complex behavior have "gray" areas. The following is one "definition":

"Differing approaches to pest control are equally notable. In chemical horticulture, a specific insecticide may be applied to quickly kill off a particular insect pest. Chemical controls can dramatically reduce pest populations in the short term, yet by unavoidably killing (or starving) natural control insects and animals, cause an increase in the pest population in the long term, thereby creating an ever increasing problem. Repeated use of insecticides and herbicides also encourages rapid natural selection of resistant insects, plants and other organisms, necessitating increased use, or requiring new, more powerful controls.

In contrast, organic horticulture tends to tolerate some pest populations while taking the long view. Organic pest control requires a thorough understanding of pest life cycles and interactions, and involves the cumulative effect of many techniques, including:[6]
Allowing for an acceptable level of pest damage
Encouraging predatory beneficial insects to flourish and eat pests
Encouraging beneficial microorganisms
Careful plant selection, choosing disease-resistant varieties
Planting companion crops that discourage or divert pests
Using row covers to protect crop plants during pest migration periods
Rotating crops to different locations from year to year to interrupt pest reproduction cycles
Using insect traps to monitor and control insect populations

Each of these techniques also provides other benefits, such as soil protection and improvement, fertilization, pollination, water conservation and season extension. These benefits are both complementary and cumulative in overall effect on site health. Organic pest control and biological pest control can be used as part of integrated pest management (IPM). However, IPM can include the use of chemical pesticides that are not part of organic or biological techniques.[7]"

------------------------------
Back to Illusion and other roses that apparently lose their ability to fight off blackspot after several years in the same spot. Why?

1)An immediate thought is that the blackspot mutated. But why would that happen if normal garden sanitary practices were followed?

2)Did something kill the good "fungi" that were keeping the blackspot under control?

3)Was the plant being weakened by a change in the soil chemistry?

i.e. in general things happen for "reasons". The hope is to discover more and more of these "reasons" through controlled scientific research, but tomorrow's research requires "new blood" and right now we are not convincing enough of our young that science is worth majoring in.

A recent contribution as to why the behavior of blackspot resistance may vary from cool to hot climates is discussed in the following thread:

http://forums2.gardenweb.com/forums/load/roses/msg0211223428132.html

The article only mentions spraying for disease, not for insects.

In my area BS is my most serious pest. I do have millions of JBs, thrips, etc, but somehow for me it is easier to just wait on them. Usally here beneficials take care of thrips by mid summer and JBs are only for 8-9 weeks, but BS is always here spring, summer and fall.
Olga

"biocontrol" is one method that one can try for blackspot.
The following may be useful in putting the concept of biocontrol into layman terms:

"Disease-suppressive soil microorganisms have been found in many places. In monoculture wheat the severity of "take all" disease often decreases within three to five years. This phenomenon is known as "take all decline," and is considered an effective natural control. Although the mechanisms are not completely understood, the decline is associated with changes in soil microorganisms that compete with and prey on the fungus. Melon plants grown in the Chateaurenard region of France do not show Fusarium wilt symptoms even though the fungus is present in the soil. Soils with suppressive characteristics tend to develop slowly and are usually found in fields where perennial crops or monocultures have been grown for many years.
Suppressiveness may be lost if the monoculture is interrupted even for one year, or if pesticides are applied. For example, researchers first recognized soils suppressive to cereal-cyst nematode when nematode numbers increased after application of a broad-spectrum biocide. Many species of fungi and bacteria in the genera Trichoderma, Streptomyces, Bacillus and Pseudomonas suppress diseases, but at this time only a few strains are commercially available. Additional commercial products may be available soon, however, as this is currently an active research area."
The quote was taken from:
Http://www.cals.ncsu.edu/sustainable/peet/IPM/diseases/org_cert.html
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The following article from the Maine Rose Society web page ( http://www.mainerosesociety.com/articles/control.html ) was written by by DR. LAKSHMI SRIDHARAN, who should be familar with those of you that are members of the American Rose Society.
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Examples that friendly fungi do exist:
Http://taylorandfrancis.metapress.com/app/home/contribution.asp?wasp=59ghxnlylp03feg2dr2p&referrer=parent&backto=issue,1,10;journal,2,54;linkingpublicationresults,1:100635,1
Http://taylorandfrancis.metapress.com/app/home/contribution.asp?wasp=4g1ltlxhtr3ya223recn&referrer=parent&backto=issue,8,10;journal,4,54;linkingpublicationresults,1:100635,1;
Http://taylorandfrancis.metapress.com/app/home/contribution.asp?wasp=8000375kwm5qnk5e7y47&referrer=parent&backto=issue,1,10;journal,6,54;linkingpublicationresults,1:100635,1;
Http://taylorandfrancis.metapress.com/app/home/contribution.asp?wasp=07wckmqrxr3jqg6kducy&referrer=parent&backto=issue,9,10;journal,7,54;linkingpublicationresults,1:100635,1;
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Blackspot on roses is scientifically called "diplocarpon rosae". The link below reports that trichoderma harzianum is a promising control - see their exact wording (the document is a PDF document. The applicable section is easily found by typing diplocarpon into the PDF find command - the binoculars).
Http://www.gtz.de/ecosan/download/Bangalore03-Ramanujam.PDF
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Title: The Abundance and Structure of the Root-Associated Microbial Complexes of Two Greenhouse Rose Cultivars.
Authors: Polyanskaya, L. M.; Ozerskaya, S. M.; Kochkina, G. A.; Ivanushkina, N. E.; Golovchenko, A. V.; Zvyagintsev, D. G.
Authors affiliation: Faculty of Soil Science, Moscow State University, Vorob'evy gory, Moscow, Russia.
Published in: Microbiology (Moscow, Russian Federation)(Translation of Mikrobiologiya), volumn 72, pages 496-502, (2003).
Abstract: "The study of the root-assocd. microbial complexes of affected and healthy rose plants of two cultivars (Grand gala and Royal velvet) grown in a greenhouse showed that the biomass of eukaryotic microorganisms in the rhizoplane and rhizosphere of healthy rose plants and in the surrounding soil was considerably lower than in the same loci of affected plants. In contrast, the biomass of root-assocd. prokaryotic microorganisms was higher in the case of healthy than in the case of affected rose plants. The root-assocd. bacterial complexes of both affected and healthy rose plants were dominated by the genera Arthrobacter, Rhodococcus, and Myxobacterium and did not contain phytopathogenic bacteria. The root-assocd. fungal complex of healthy roses was dominated by fungi of the genus Trichoderma, whereas that of the affected rose plants was dominated by the species Aureobasidium microstictum. The affected cane cuttings and cankers occurring on affected canes were found to contain Coniothyrium fu-ckelii (the causal fungus of rose stem canker) and sclerotia of Botrytis cinerea (the causal fungus of gray rot). The micromycete complex of healthy rose plants was not so diverse as was the micromycete complex of affected rose plants."
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Title: Biological control of black spot of rose caused by Dipocarpon rosae .
Authors: Prasad, R. D.; Rangeshwaran, R.; Sunanda, C. R.; Vinita, J.
Authors affiliation: Project Directorate of Biological Control, Post Bag No. 2491, H.A. Farm Post, Bellary Road, Hebbal, Bangalore 560 024, India.
Published in: Annals of Plant Protection Sciences,volumn 10, pages 256-259, (2002).
Abstract: "Fungal biological control agents (Trichoderma harzianum , T. viride and Chaetomium globosum ) were used either alone or in combination with fungicides (chlorothalonil and mancozeb) to manage black spot of rose caused by D. rosae under greenhouse conditions. Black spot incidence in biological control agent and/or fungicide treatments was significantly low (disease ratings from 0.33 to 3.33) compared to the control at all observation dates. After 100 days of spraying, defoliation was lowest with chiorothalonil, Trichoderma harzianum +chlorothalonil, C. globosum +chlorothalonil and T. harzianum +mancozeb treatments. The highest mean vigour index was recorded in T. harzianum treatment. The highest flower production was recorded in C. globosum +chlorothalonil treatment (4.33) followed by T. harzianum alone and T. harzianum +chlorothalonil treatment (4.00)."
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Cornmeal is considered to be a good food for the friendly fungus "trichoderma harzianum". The fungus is available commercially, see:
http://www.ipmofalaska.com/files/trichoderma.html
There may be another benefit to this fungus as there is a report that it helps root growth:
Title: Effect of Trichoderma Colonization on Auxin-Mediated Regulation of Root Elongation.
Author: Bjoerkman, Thomas.
Department of Horticultural Sciences, Cornell University, Geneva, NY, USA.
Published in: Plant Growth Regulation, volumn 43, pages 89-92, (2004).
Abstract: "The biocontrol fungus Trichoderma harzianum 1295-22 increases root growth in addn. to roles in suppressing disease. Its agricultural use could be expanded if the mechanism of growth enhancement were known. Among the proposed mechanisms of growth enhancement is that the fungus counteracts auxin inhibition of root-cell elongation. We tested whether there was evidence for a secreted auxin inhibitor, for enhanced auxin degrdn., or for altered auxin sensitivity. Our results provide no support for any of these mechanisms. Trichoderma secretions inhibited growth, whereas an auxin inhibitor would increase growth. Auxin inhibited growth to the same extent in colonized and uncolonized roots, indicating no change in auxin sensitivity. Endogenous auxin levels maintained growth closer to the max. in uncolonized roots, indicating stronger auxin limitation of growth in colonized roots. These tests indicated that Trichoderma-colonized roots had a faster max. growth rate, but an unchanged response to auxin."
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Even if naturally occurring trichoderma harzianum only reduces the amount of blackspot fungus by 10 to 20 % (the numbers are just a guess), there are probably going to be a number of different "friendly" fungi in an organic garden.
For example, the following paper reports that 2 fungi that are now recognized as biocontrol potential have increased levels on blackspot infected leaves:
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Title: PHYLLOPLANE MICROORGANISMS OF ROSA CULTIVAR PICADILLY FOLLOWING INFECTION BY DIPLOCARPON-ROSAE
Author: HAYES A J
Author Affiliation: DEP OF FORESTRY AND NATURAL RESOURCES, UNIV OF EDINBURGH, UK.
Published in: Transactions of the British Mycological Society, volumn 79, pages 311-320, (1982).
Abstract: "The phylloplane microflora of the hybrid tea rose cultivar Picadilly was studied for 2 growing seasons on healthy leaves and on leaves infected by D. rosae. Large increases in numbers of yeasts and bacteria on healthy leaves were noted from the end of July until the beginning of Oct. Late in the growing season numbers of all types of microbes increased dramatically. Following infection by D. rosae numbers of microbes generally showed a marked increase, but this was not always sustained. Cryptococcus laurentii and Micrococcus sp. populations on infected leaves were 3-4 times those on correspondingly healthy leaves. The species composition and changes in numbers of phylloplane microbes are compared with descriptions of microflora isolated from leaves of other plants and possible reasons for the observed differences are discussed."
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The following two links are Google searches for the two fungi listed and the word biocontrol.
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Http://www.google.com/search?hl=en&lr=&q=%22cryptococcus+laurentii%22+biocontrol&btnG=Search
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Http://www.google.com/search?hl=en&lr=&q=micrococcus+biocontrol&btnG=Search
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The science of biocontrol is still in its infancy. The use of Chitosan is one of the early results of this area of research.
The following is the EPA summary:
( Http://www.epa.gov/pesticides/biopesticides/ingredients/factsheets/factsheet_128930.htm )
"SUMMARY
Chitosan is used primarily as a plant growth enhancer, and as a substance that boosts the ability of plants to defend against fungal infections. It is approved for use outdoors and indoors on many plants grown commercially and by consumers. The active ingredient is found in the shells of crustaceans, such as lobsters, crabs, and shrimp, and in certain other organisms. Given its low potential for toxicity and its abundance in the natural environment, chitosan is not expected to harm people, pets, wildlife, or the environment when used according to label directions."
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There is a scientific literature report of 10 - 20 % effectiveness against blackspot.
Title: Chitosan as the biocontrol agent of fungal pathogens; activity and mode of action.
Authors: Wojdyla, Adam T.
Authors affiliation: Research Institute of Pomology and Floriculture, Skierniewice, Pol.
Published in: Bulletin of the Polish Academy of Sciences: Biological Sciences, volumn 51, pages 159-165, (2003).
Abstract: "In in vivo expts. showed that chitosan added to potato dextrose agar at 3 mg/cm3 in 50% suppressed radial growth of Colletotrichum gloeosporioides and Phytophthora cryptogea. Another tested fungi were less sensitive to chitosan. ED50 for Cylindrocladium scoparium and Myrothecium roridum was more than 5 mg/cm3. In vivo expts. showed that only 10-20% effectiveness of the compds. against Diplocarpon rosae was found, when chitosan at 0.2-0.4 mg/cm3 was used for rose spraying. Also spraying of willow 2 times at weekly intervals against Melampsora epitea decreased the mean no. of rust pustules per leaf. Spraying of dieffenbachia 24 h before inoculation with M. roridum resulted in significant decrease of necrosis spread on leaves. Five days after inoculation the compds. inhibited the development of leaf spot about 94%. Chitosan applied preventively before inoculation of leaves gave significantly better results in the control of M. roridum than used 24 h after inoculation. Spraying of chrysanthemum, naturally infected with Puccinia horiana decreased the mean no. of pustules per leaf about 95%."

Get down, Henry...lol

Someone needs to invent some infrared Blackspot spore detecting garden googles.
We could then track & understand this fungus disease better.
Maybe were better off not seeing it. LOL

Good articles Henry!