AusBonsai

Gday everyone

Need some quick advice. I can't figure out what these black spots on my banksia trees are. Its only appeared recently. Any advice what they are and how to treat them?

Cheers

I have had similar spots on my banksias from time to time, including ones growing in the garden. I don't know what they are but I have always assumed they are little fungal spots (the absence of any leaf damage has caused me to rule out bug poo, although I have wondered about aphids). In my experience, they tend to appear on older leaves and since they seem to cause no damage to the tree I have taken to ignoring them. I am ignoring the ones I have at the moment.

I still have the spots. I haven't had anyone identify what it is.

Any help identifying the black spots?

The nursery trade often can have them on Banksia leaves. If you leave it they spread. Just scratch them off whenever you see them. I think they’re tiny suckers of some sort. They eventually spread to the trunk too. I just scrape them all off and eventually it got rid of the problem. They will also move to young leaves if you ignore it.

Definitely need to get rid of them,. If they get in large numbers the leaf will be sucked dry and the branch can die back badly. You can cut back hard to get rid of the bulk of it and grow new growth. It has been a bad year for it this problem. Keep the tree in full sun to lessen the possibility of infestation.

You could spray with a safe insecticide, and this should reduce populations.

I have had this problem on 3 out of 4 of my banksia integrifolia, but not on the Marginata or Serrata.

Cheers,

Grant