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despite the good feeding and watering I've been plagued by black spot again. Next spring I'm thinking of cutting them right back to about a foot in height and drenching the stems and surrounding soil with diluted jayes fluid as I've been told the black spot overwinters there. Would I be doing any harm to the soil or roses by doing this.
Jeyes fluid is a very nasty substance produced as a by-product of the coal industry. Besides sorting out the odd bit of blackspot it will also kill all the good bacteria and living creatures in the soil stone dead. You will notice that tins of Jeyes fluid tell you to avoid contact with the stuff. That's because it does us no good either. It is extremely toxic to all living things.
Blackspot is an air-borne fungus in the same way that mildew is. It flies around all the time in the air and is constantly landing on the soil. When the rain falls, water droplets bounce up from the earth and land on the rose stems and leaves. The fungus gets onto the plants by being splashed up there.
The best way to ensure that you don't suffer from blackspot is to do the following things:
1 Pull off and burn or bin all affected leaves on the plants. Now.
2 Pick up all diseased leaves from the ground and burn or bin them too.
3 Try to make sure that any pruning you do is on a dry day and, if possible, is above the "bounce" level of a raindrop. If the leaves and stems are pruned when they are dry, the cuts will have time to harden and dry off and resist the rain and the fungus.
4 Keep doing all of the above for ever......
thanks for your reply WB I try to all the above but am still battling with it and was thinking of turning to Jeyes as a last resort. I'll keep in mind what you have said about the pruning.cheers
make sure the leaves and any stems that drop or you cut off are put in the bin because if left will spread.
If you are having problems after all the good housekeeping, it may be that you need to grow a more resistant variety of rose. Some suffer terribly whatever you do.
Waterbutts´ advice is excellent.
My roses suffer from black spot (along with a myriad of fungi...) because
of my garden´s poor drainage. A solution of copper sulphate is easily
available at garden centres, and does well against this stubborn disease
(be stubborn yourself, spraying every week).
Remember the black spot´s spores remain on the damp ground ready to
spring back to the plants once it rains or the plants are watered; do not allow
any fallen (diseased) leaves there. If you find an inert sort of mulching (like
pine bark), it will help prevent this "boomerang" effect.
maybe that would be the answer, I usually spray about 4 times a season, I'll try the copper sulphate next time. I took up the bark mulch a couple of years ago because I wanted to underplant with geraniums and phlox so maybe I've added to the problem without realising.