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Blackspot

KD

Blackspot

by 4 years ago
11
If a rose has Black Spot and my efforts to control it (remove diseased leaves, spray with sulphur every 2 week) hasn't eliminated the problem should I throw the rose out?     
AM
4 years ago
Hi Karen - I would remove all leaves and cut back - feed with rose food, water well and see what happens. Make sure you clear up any leaf litter too and spread a layer of compost over the ground around the plant to bury any spores. Some varieties are just susceptible so if the problem persists and you really can't get rid of it - get rid of the rose and start again with a more resistant variety. Lif's too short to live with a miserable plant!
KD
4 years ago
Thank you, Andy! Great point about ditching miserable roses. Any guidance on cutting back? How low? When? Now in summer or early/late fall?
MM
4 years ago
Andy is absolutely right about ditching varieties that are susceptible to blackspot. The other thing though you might like to try is foliar feeding which is simply a matter of mixing up a suitable fertiliser in a watering can and wetting as many of the leaves as possible. I always think the seaweed based Maxicrop (if you're out of the UK I'm pretty sure there are locally available seaweed based foliar feeds) is very good. but remember if you water in the evening and the leaves stay wet overnight that is the best way of encourage blackspot. Always best to water in the morning when the leaves can hopefully dry out quickly. in terms of cutting back you can cut them right back to 15cm, roses are amazing for their ability to sprout from v old woody bases. Do this in winter between December and the end of February.
KD
4 years ago
Thank you, too, Michael. I do know not to water at night. I have even installed drip irrigation so that my roses are not watered from overhead day or night. I am intrigued by your recommendation about foliar feeding...how does that mitigate my Blackspot problem? I am unfortunately out of the UK, I wish I were there because I think UK gardeners and all their tools and products are the best of the best. Ps on the topic of cutting back, being new to climbing roses I have a question, whereas I want my climbers to cover an arbor, I would not cut them back, correct? I've had a lovely Candy Cane climber (pink and white variegated petals) for 3 years that comes back each year (with a mild case of Blackspot unfortunately) but it never makes it up and over the arbor. Karen
MM
4 years ago
The foliar feed acts to help boost the resistance of the leaf. Seaweed based products have a very long history of helping plants (and humans/animals) grow and stay healthy. So it wont cure the blackspot but if put on at the start of the season and on a fairly regular basis then will help to keep it at bay. I had a quick look on Google and I think fairly easily available in the States (if indeed that is where you are) but I think readily available worldwide. I know in Australia they are mad keen on it. No you shouldn't cut back the long canes of climbing roses until they've reached the height you want them to be at. The only pruning you should do is of the side shoots that flowered the previous season, reduce them in length to about 4"/10cm in winter. Michael
KD
4 years ago
Thank you for this information Michael. You taught me 2 things I didnt know. And yes I'm in the US. Our exchange will lead me to post another question about growing climbers as I am not getting the results I'd like. Thank you again.
EB
4 years ago
Hi Karen - (just in case you didn't know already), Michael is the Chief Rosarian at David Austin Roses. His expertise is probably unrivalled in the industry.
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MM
4 years ago
Very glad I was able to tell you something you didn't know. I look forward to your next question Michael
KD
4 years ago
I did not know that, Elspeth. That makes Michael a rock star in my world! As the moderator, would you like me to start a new thread to ask my rock star a new question about climbers rather than ask it here? ;-)
EB
4 years ago
He is indeed the rockstar of the roses world. Shhh don't tell everyone the experts hang out here! Yes please new thread. There are some climbers world experts lurking.. Let's see who we get ;)
KD
4 years ago
Andy or Michael, I am concerned that some small black spotted leaves may be in the mulch. Should I remove ALL mulch now and replace or can it wait until spring? Karen

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