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Halt the rise of black spot, organically.


 
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James Kilkelly
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PostPosted: Fri Jun 08, 2007 7:23 pm    Post subject: Halt the rise of black spot, organically. Reply with quote

Halt the rise of black spot, organically.

Its back! Black spot has once again raised its ugly mottled head to infect the roses of Ireland (including mine), causing leaf loss, and die back of the plants stems. Black spot (Diplocarpon rosae) is a fungal disease encouraged by much the same conditions that encourage potato blight, which are warm, moist locations with stagnant air. Most Irish roses especially those grown in areas of high rainfall are destined at some stage of their growing life to play host to blackspot.


Black spot (Diplocarpon rosae) symptoms, photo / pic / image.
Scientific classification
Kingdom: Fungi
Division: Ascomycota
Subdivision: Pezizomycotina
Class: Leotiomycetes
Order: Helotiales
Genus: Diplocarpon
Species: Diplocarpon rosae

Maybe you are lucky enough to have never had a run in with blackspot, and therefore you require an introduction to help you identify this plant ill. Black spot is aptly named, initially appearing as purple or black circular spots with yellow-fringed halos. Over a short period of time these halos spread and join up causing the leaves they appear on to yellow and shed prematurely.

Although black spot will rarely kill a rose outright, it will however leave you with a sickly, twiggy rose, which flowers poorly due to a lack of its life-giving leaves. Now, there are many combined chemical products available in your garden centre for the control of blackspot, for example Rose-clear, Benlate or Multirose, to name a few. But you may actually have all the raw materials already within your kitchen to create your own homemade, organic and most importantly safe black spot spray.

Method 1, Milk.
Walk across your kitchen as far your fridge. Mix equal parts milk and water, then apply this each week with an atomiser or a sprayer to the upper and lower section of the roses leaves. This milky solution causes an invisible and friendly fungus to form, which will help prevent the formation of the dreaded black spot.

Method 2, Baking soda.

Mix one tablespoon of baking soda or baking powder into one litre of water and add a drop or two of washing up liquid for stickiness. Again, apply this each week with an atomiser or a sprayer to the upper and lower sides of the roses leaves. The baking soda (Sodium bicarbonate) causes the rose leaf surface to become exceedingly alkaline which again prevents the blackspot from thriving. Both method 1 and 2 are effective only if used at the first sign of symptoms.

Method 3, The rake and clippers.
It is important to rake up the withered rose leaves and petals that litter your beds and borders, as these can act as a breeding ground for the blackspot fungus. Also, pick or snip off any live leaves that exhibit black spots, as well as looking unsightly they aid the spread of the disease. All infected rose leaves and clippings should be burnt not composted.

Method 4, The shovel.

When all is said and done, probably the best method of organic black spot control is to plant roses resistant to the disease. And there are quite a few.

Black spot resistant roses include...

Amber Queen (golden yellow),
Iceberg (white),
Trumpeter (red),
Electron (Deep pink),
Helmut Schmidt (Golden yellow),
Just Joey (Creamy peach),
Keepsake (Dark pink),
Las Vegas (Dark peach with yellow highlights),
Peter Frankenfeld (Dark pink),
Polarstern (White),
Precious Platinum (Medium red),
Silver Jubilee (Salmon pink),
Voodoo (Orange),
Love (Crimson red with white backs),
New Year (Orange),
Tournament of Roses (Rose pink),
Bonica (Rose Pink),
Escapade (Mauve-pink),
Europeana (Dark red),
Impatient (Orange-red),
Liverpool Echo (Orange),
Matangi (Red),
Orangeade (Orange-red),
Play Girl (Bright pink),
Playboy (Reddish orange),
Redgold (Golden yellow edged in dark pink),
Regensberg (Pink and white),
Sarabande (Orange-red),
Sexy Rexy (Rose-pink),
Showbiz (Scarlet red),
Viva (Red).

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Last edited by James Kilkelly on Thu Jun 21, 2007 10:42 am; edited 1 time in total
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GarethAustin
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PostPosted: Wed Jun 20, 2007 4:59 pm    Post subject: Reply with quote

I have another practice on keeping roses disease free, and it comes from the old method of preventign blight on potatoes.

Use Sulphate of Potash in Spring and early summer as a feed for the roses. Teh growth which develops is less soft and more disease resistant. Also as the foliage is harder they are less prone to pest attack.

Mulch in Autumn with Turf or wood ash as a soil improver.
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James Kilkelly
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PostPosted: Thu Jun 21, 2007 10:41 am    Post subject: Reply with quote

GarethAustin wrote:
I have another practice on keeping roses disease free, and it comes from the old method of preventign blight on potatoes.

Use Sulphate of Potash in Spring and early summer as a feed for the roses. Teh growth which develops is less soft and more disease resistant. Also as the foliage is harder they are less prone to pest attack.



Both the potato and the rose suffer from a disease which is quite similar, so your tip makes sense, GarethAustin.

GarethAustin wrote:

Mulch in Autumn with Turf or wood ash as a soil improver.


One for the tip book.

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PostPosted: Thu Jun 21, 2007 2:10 pm    Post subject: Reply with quote

GPI

Any other good uses for turf and turf ash?

I have an uncle who always take some turf back to London with him to burn in the back garden to keep midges and flies away.
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James Kilkelly
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PostPosted: Thu Jun 21, 2007 3:35 pm    Post subject: Reply with quote

GarethAustin wrote:
GPI

Any other good uses for turf



Raised beds in my own garden.


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GarethAustin
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PostPosted: Fri Jun 22, 2007 7:49 am    Post subject: Reply with quote

Whats the small blue flowerign plant in the raised bed?
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Gardensgalore
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PostPosted: Fri Jun 22, 2007 10:01 am    Post subject: Reply with quote

If you garden on an acid soil like I do, turf or wood ash works wonders for all the rose family (roses, fruit trees, pyracantha, chaenomeles etc). They need the alkalinity to free up potash in the soil; and thats another ingredient...potash....hence the name. It works wonders for disease resistance, and flower/fruit production. A could dollop of DRY ash around them in Spring is best. Rain washes the active ingredients out of ash very quickly.

Put please keep it well away from your lime-haters. (rhododentron, erica, arbutus, and quite a lot more, best to keep the ash to rosaceae)

One more word of warning....Beware ash contaminated with coal, paint or plastics... it could contain plant toxins.

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James Kilkelly
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PostPosted: Fri Jun 22, 2007 11:07 am    Post subject: Reply with quote

GarethAustin wrote:
Whats the small blue flowerign plant in the raised bed?


Its Geranium ibericum 'Johnson's Blue'.
Quite commonly planted, but common for a good reason.

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danmac
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PostPosted: Fri Nov 30, 2007 5:25 pm    Post subject: Reply with quote

I've resorted to desperate measures in my attempts to rescue one of my new little roses which is suffering badly from this wretched fungus.
Amongst the new bare root roses which I put in at the start of October was a climbing variety named "Schoolgirl". All of the other varieties, about 20 in all that I planted, are off to a great start and are showing good progress with lots of healthy shoots. But poor "Schoolgirl" immediately began to show black fungal infection in its cut off stem. I cut off the infected piece and regularly spray it with fungicide but the fungus came back and even infected the higher up of the 2 growing buds which I then had to remove and cut the stem even lower.
At that point I soaked a rag with a solution of a winter wash called Armillatox and for want of a better word squeegeed the remaining stem of my rose with this. I also drizzled the remain solution around the bed of the affected rose but avoided getting any on the one remaining leaf shoot/bud as I was told that it would make the leaves fall off.
Today I examined my rose again and was horrified to see that the black was again beginning to appear at the cut edge of the stem, which is about an inch and a half above the only remaining bud. (There is only about an inch and a half of stem remaining above ground altogether, the leafy bud is more or less growing out at ground level.)
So this time I decided to try a different approach. I had mixed some Roseclear earlier for use on some indoor plants (I find it is good for keeping mildew off my gerberas) and had a bit left over in my spray bottle. I took a small ball of cotton wool and soaked it with Roseclear, placed the cotton wool over the top of the stem, wrapped a bit of plastic over this and sealed the whole lot with an elastic band.
I am hoping that the sealed in Roseclear in the cotton wool, will keep the fungicide in constant contact with the end of the stem area, where the fungus is trying to spread and that this will provide an intolerable environment for the blackspot. It was my intention to replenish the cotton ball every second day in the hope of giving the growing bud a chance to sprout and harden. I did this because I was afraid to cut away any more of the stem, as so little remained.
So, do any of you reckon this will succeed or is my "Schoolgirl" doomed?
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volga
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PostPosted: Sun Dec 02, 2007 8:22 pm    Post subject: Reply with quote

danmac, I suppose you have to resort to any measure now to save your rose. I just wonder how much of a constant supply of roseclear a rose can take. Spring is not too far away so it will be interesting to see if some new blackspot free buds and shoots will be produced.
Good luck with it, and keep us posted.
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danmac
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PostPosted: Tue Dec 04, 2007 5:31 pm    Post subject: Reply with quote

Well the Roseclear is well diluted but it still has that distinctive "death is coming for you fungi and aphids" smell. Took off the first cotton ball today, the fungus hadn't spread! Replaced it with another drop of RC and a new cotton ball wrap. Roll on April and the growth spurt again!
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breezyacre
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PostPosted: Mon Jun 06, 2011 6:02 pm    Post subject: Reply with quote

fMany thanks everyone for this very interesting thread. Will just add my tuppence worth. I have two american pillers which I am very fond of and which are, unfortunately covered in black spot. I couldn't just cut away the infected leaves as that would leave very little. The plant is growing strongly and i have mulched every year. I will though use the milk and water and the bicarb and water and indeed the sulphate of potash next year as a preventative. Many thanks for all the advice.
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