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How to treat Bouganvillea and Impatient with brown leaves and white marks?

My bougainvillea seems otherwise quite healthy but some leaves are turning brown and crispy while some of them have these white marks.

Same with my Impatients ( it is flowering beautifully) but I have just noticed these white marks. I have checked the plants and don’t see any aphids, mealy bugs or spider mites.
I cannot work out what could be causing this issue?

Any advise would be great. thanks!

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Planting and Growing

Comments

JacobZ

Hi @Greg_r,

It looks like your plants are experiencing some issues from powdery mildew. Powdery mildew is a common fungal disease that appears as white, powdery spots on leaves, stems, and buds. It thrives in warm, humid conditions with poor airflow and can affect a wide range of plants, including bougainvillea and impatiens.

At first, you’ll notice small white or greyish patches on the leaves, which can spread quickly. Over time, the affected leaves may turn yellow, then brown and crispy as they dry out and die. While powdery mildew rarely kills plants, it weakens them, reduces flowering, and can make them more vulnerable to other issues.

To manage it, improve airflow around your plants, avoid excess watering of the leaves focusing mainly on the roots of the plant, and treat with applications of Fungus Gun Systemic Disease Spray, ensuring you closely follow the instructions on the label. Regular pruning and removing infected leaves can also help keep it under control.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

Cathy91

https://www.workshop.bunnings.com.au/discussion/comment/49221#Comment_49221

i have a Bougainvillea that normally blooms magnificently in late September/ October. But this year it barely has any leaves and I’ve noticed this fungus or powdery mould on the branches.

I gather it could be because of all the rain we’ve had. I’ve recently added fertiliser to the soil. Should I use Yates Fungus gun for these spots? Do I spray it on the markings or generally all over?

Any suggestions to help improve the condition?

The Bougainvillea is well over 30 years old and now I’m very concerned I may lose it.

i would appreciate any help or suggestions.

Thank you,

Cathy

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/90613#Comment_90613

Welcome to the Bunnings Workshop community @Cathy91. It's wonderful to have you join us and many thanks for your question on Bougainvillea care.

Those grey patches you can see on the branches are actually lichen rather than a fungus. Lichen is a perfectly natural growth that often appears on older timber and bark, and it doesn’t harm the health of your plant. So you don’t need to worry about spraying it with a fungicide like Yates Fungus Gun — that won’t really make any difference here.

What is a bit more concerning is the state of the bark in your photos. It looks like some areas are peeling away and the underlying wood is exposed. On a Bougainvillea that’s over 30 years old, this could simply be a sign of age. Bougainvilleas can live for decades, but like many long-lived plants, they sometimes develop sections that start to deteriorate.

It may be worth considering a bit of rejuvenation pruning. If there are branches that have lost their bark or look quite woody and lifeless, removing them can encourage the plant to put its energy into healthier stems. A good tidy-up and thinning out can also improve airflow through the canopy, which helps reduce stress and makes the plant less prone to pests and disease.

Since it’s struggling to put on new leaves, I’d suggest holding back on fertiliser for now and instead focus on careful pruning and checking that the soil drains well (Bougainvillea dislike sitting in waterlogged conditions, which can easily happen after lots of rain). Once the plant starts to push out fresh growth again, a controlled-release fertiliser suited for flowering plants can help it along.

Given its age, it may not bounce back to the lushness it once had, but with some selective pruning and good care, there’s every chance it will recover and keep rewarding you for years to come.

Please let me know if you have any questions.

Mitchell

Cathy91

https://www.workshop.bunnings.com.au/discussion/comment/111212#Comment_111212

Thank you so much Mitchell, I really appreciate your response, and am quite encouraged by your suggestions.

i did go up to Bunnings last weekend and was advised Osmocote Premium Plus, but won’t add any more for now.
The branches are quite tight and tangled so I will try to thin out the lifeless ones.

Many thanks,

Cathy

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