Black spots on my summer beauty’s leaves

by Jeff Tischler
(North west sydney)


Hi I have two summer beauty’s in my front yard north facing and both get plenary of sun. They are about 8 years old, one grows faster than the other due to having more sun each day I assume. The larger one last year starting developing black spots on the leaves and is spreading quite quickly. I was hoping you might be able to suggest some treatment for it as I love it and the flowers it produces for the wildlife around.

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Nov 12, 2021
 Perfect timing!
by: Jacki Cammidge, Certified Horticulturist

I'm going to assume that your plants are Buddleia davidii 'Summer Beauty' so this is advice for that plant.

All Buddleia (butterfly bush) will regrow after being cut back hard in the spring, so this is perfect for you in the southern hemisphere! Usually, it's recommended to do this in May, but in your area, that would be November. So get the pruners out, and cut ALL the growth off as close to the base as possible. Burn or dispose of the pieces in the garbage - don't compost them, or keep them in the garden. You should also rake up any leaves from below the plants, to keep the pathogen from reinfecting the plant. This type of leaf spot is generally either fungal, and thrives in damp conditions, or bacterial which can happen any time.

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