Black spot on roses.

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Trixi Agrios
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Does anyone have a remedy for black spot on roses. The roses look beautiful except they are now showing blackspot on the leaves. They are all in large ceramic pots. In very good soil and have been fertilized with Andrew’s special mix. (From the course). I am spraying them with baking soda mixed in a gallon of water, with a bit of vegetable oil and liquid soap. Not helping!
jack oostenbrink
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Hi Trixi, you are asking about combating black spot when the conditions for blackspot are perfect! Cool moist weather makes this common rose problem even worse. You are doing the right thing with the baking soda. In addition, remove the fallen leaves, prune a bit to thin and open the plants and allow more air circulation, water only the roots and not the leaves, and ensure the brightest and sunniest location possible.
In the future if you buy other roses, do a online search for blackspot resistant varieties such as Iceberg.

If they were my plants (Im a bit of a tough love guy when it comes to plants) I would give them a hard cut back and remove all the leaves to prevent reinfection and encourage strong fresh growth. With the onset of dryer and sunnier days you will notice the problem disappear in the cut back plants.
The disadvantage is that you will lose your flowers till mid to late august, the advantage is that you will have gorgeous shiny new foliage within a few weeks.

Good luck!
Trixi Agrios
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Joined: Sat 01-Jan-2022, 22:41
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Thank you Jack. I’ll give it a try.
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