As the garden settles into a quieter rhythm, November brings a wonderful second wave of rose blooms from reliable repeat bloomers. With their gentle glow, these flowers seem even more plentiful and stick around longer because of the cool weather and damp conditions.
While these stunning plants might look great from a distance, it’s definitely worth getting up close for a proper inspection. If you notice any yellowing leaves with black spots scattered across them, that’s your cue to jump into action right away. Taking great care of your roses and keeping these lovely plants thriving means staying on top of pest and disease management. Black spot stands out as one of the biggest challenges rose growers face, but November is the perfect time to tackle it, and gardening expert William Mitchell of Sutton Manor Nursery has shared how to put an end to the disease.
What is black spot disease?
This time of year, roses can be extremely susceptible to diseases. One of the “most dangerous diseases” that is common within roses is black spotting.
William said, “This is by far the most dangerous disease that a rose can get. The disease is caused by a fungus called Diplocarpon rosae. This fungus attacks the leaves and greatly reduces plant vigour.”
Blackspot typically begins as dark spots on the leaves, black or deep brown, occasionally with a purplish hue. These spots feature a somewhat fuzzy border and frequently display a yellow halo surrounding them. They generally emerge on the lower leaves, those nearest to the ground where rain and water splash can transport fungal spores from the soil.
As time goes on, these spots expand, sometimes blending together into larger patches that cause the leaves to turn yellow. When this occurs, the leaves fall away, and your rose loses a significant portion of its leaf surface, which it requires to absorb sunlight and produce energy.
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How to stop black spot disease
Of course, prevention is the best cure; however, when black spot does make an appearance, “clearing away these leaves that have been affected by black spots is vital”, instructed William.
He added, “This is because the diseases can spread uncontrollably and can even reinfect when the following spring comes along.” Removing the affected leaves and pruning out any infected stems should be a five to 10-minute job.
Don’t forget to keep your pruning shears and tools clean and disinfected! Just give them a quick wipe down with alcohol or another good disinfectant, and you’ll prevent spreading fungal issues from one plant to the next.
Once the leaves have been removed, the gardening expert urges, “Dispose of these infected leaves as quickly as possible to make sure that the fungal disease does not spread throughout the garden.”
Don’t throw them into your compost heap because that just gives the fungus the opportunity to return to your plants next season. Instead, bag them or add them to green waste for disposal.
