I think I have found cure for "Rose Blackspot"

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Digger
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#2967 I think I have found cure for "Rose Blackspot"

Post by Digger » Sat Apr 06, 2019 5:04 pm

A cure for “Rose Blackspot”

I have trialled this over about 2 years and I am convinced it works.

In June 2017 one of my climbing roses was ravaged by blackspot and it was completely devoid of foliage.
The pundits reckon that the fungus is splashed onto the plant when it rains but I don’t agree. The blackspot was on leaves 8 feet up, and I was not convinced that the spores blow about on the wind either. Another climbing rose about 12 feet away was unaffected.
I came to the conclusion that the fungus is getting into the plant through the root system.

I make homebrew wine and it occurred to me that if the “Campden Tablets” stop wild yeast and prevent fungal growth they might stop the blackspot.
I had nothing to lose by trying out my theory, the rose would have died off anyway.

I cut the rose back to about 3 feet high and then I dissolved two campden tablets in a drop of water and then I put the solution in a gallon watering can and filled it up. I drenched the remaining stems and drenched the soil around the roots. I did this every 3 days to make sure any fungus was not missed. If it rained after I had watered the rose I did it again just in case the treatment had been washed away.
After a few days new growth appeared. It looked very healthy and the leaves were lush, and there was not any sign of blackspot.
I then watered it once a week for 6-7 weeks with the solution. Once it was obvious the rose was free of any infection I then treated it every 2-3 weeks.
The rose looked very healthy and seemed to thrive on the campden tablets. As autumn arrived I stopped watering the rose.
In about February of 2018 I noticed that moss on the path was starting to sprout which made me think that the blackspot might be waking up as well so I mixed up the same solution as last year and watered the rose again and did it approximately every 2-3 weeks.
All through 2018 the rose remained clear of blackspot. I did the same again in February of this year, (2019), and I will keep up the same routine as before. You can see from the pictures the rose looks healthy.

The time period I chose is not scientific, it just seemed a good idea at the time. How you do this, if you try it, is down to your own judgement as to what feels right. Only you can gauge the results on the plant you are treating.

Campden tablets do not dissolve quickly. I find the easiest was to dissolve them is to put two campden tablets in a meat paste jar with about 1 inch of water in the bottom and seal it up.
After about ½ an hour they will have dissolved and the solution can be poured into the watering can.
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Gnatalee
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#2986 Re: I think I have found cure for "Rose Blackspot"

Post by Gnatalee » Mon Apr 15, 2019 12:20 pm

What an interesting experiment - it is obviously having a good effect as your roses look very healthy indeed. May have to try this on mine :)


Gnats



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#2999 Re: I think I have found cure for "Rose Blackspot"

Post by Digger » Fri Apr 26, 2019 7:11 pm

Gnatalee wrote:
Mon Apr 15, 2019 12:20 pm
What an interesting experiment - it is obviously having a good effect as your roses look very healthy indeed. May have to try this on mine :)


Gnats
Hi Gnats,

I sent it to the RHS. Their reply was that cutting any rose back will keep blackpot away for a couple of years. I'm not convinced. In the past I have cut the rose back, always removed any fallen leaves and I have removed infected leaves off the plant and still it came back when new shoots showed themselves.

The RHS have asked me to keep them updated on how it pans out.

When we had coal fires blackspot was not a problem in the towns because the sulphur in the air kept it at bay.
I used Campden tablets because it stops mould in homebrew. The deciding factor was that the tablets give off Sulphur Dioxide which I thought might have the same effect as coal smoke.

Apart from watering the rose every 2-3 weeks I have now started spraying it with the same solution using a pump up pressure sprayer.

Digger.



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