AusBonsai

Hi Everyone,

I was hoping somehow more experienced with native might be able to help me solve this problem.

I have a couple of large banksia integrifolia which ha e been very healthy for the past 10 years or so. However I have noticed this beginning of winter the leaves have got black spots and I have sprayed with systemic pesticide and other recommended pesticide from gardens centre but nothing seems to help.

Can some please identify what is wrong with the leaves and what treatment is required?

Thanks so much

Jay

Have you tried wiping a leaf with a wet wipe? It could be sooty mould.

Thanks Akhi,

I did this at the beginning and did work but the sooty mould came back.

Jay

I thought sooty mould was caused by a sap sucking critter, so you may also have to deal with that as well as the actual infection.

It’s definitely a fungal problem. Move it into a sunny position that is well ventilated. Also don’t water it in the evenings especially on the leaves.
Cheers
Kirky

If it is sooty mould it is usually caused by sap sucking insects as Stevie B mentioned. They produce sugars that the sooty mould feeds on. However, it can also be from rain dripping from an overhead tree that has sooty mould. Eucalypts are known to be an issue. My ute is often parked under a Eucalypt and always has black spots.

If it were my Banksia I would use some of my stash of Fongarid drench, water it in as per instructions.

Then an insecticide for possible bugs,

Then a foliage fungicide

Then Pest Oil, I find the Pest Oil binds to the sooty mould and it just slides off, The Pest Oil also seems to make a fine barrier on the leaf and repels further mould/mildew.

Put into full sun and wind and do not overwater. (All the advice by others has been good as well)

I haven’t explored much beyond Fongarid at the moment as I still have some, I would be interested to hear what others actually use, not just talk about,

Grant

Thanks Everyone for the advice.

The banksia is always in full sun and not under any tree. No trees nearby either.

And I have been watering at the base only.

I will definitely consider a fungicide followed by pest oil.

Read somewhere that eco-Neem is good too. Has anyone tried this?

Thank you
Jay