AusBonsai

Hi Guys

As the subject suggests I have black spots on the leaves of my Coastal Banksia, they've been on for approx a year then about 4 months ago it got to the point where the tree was dying, so I went to the drastic measure and pulled it up and low and behold 1/2 to 3/4 of the roots systems was dead.

So after cleaning up and trimming back to live shoots I re potted in a normal deep garden pot. It seems to have bounced back with new shoots and leaves but the old leaves that where left still have the black spots.

Any ideas what it is and solutions?

Phil

p.s. Ill post pictures if it would help. But they just look like black spot you would find on roses.

Hi Fill,

Please post some pictures when you get a chance.

S.

Hi Phil
Yes, some images would be good.
Are the spots all on the undersurface of the leaves?

Not sure if the roots died first or the leaves. If the infestation is severe, the leaves will decline and die and if most leaves are affected, then the health of the plants declines and the roots may also die. Need to be careful in diagnosing dead roots as it can depend on the growing cycle of the tree. When the roots are dormant, they might look dead, though are still functional.

I've had black spots on the undersurface of a number of banksia species. They are a kind of scale. They can be killed by rubbing off with a finger nail or something else, if you are patient enough. You can also get at them with 'confidor' or pest oil/white oil.

If they are really like black spot on roses, visible from the upper surface too, they could well be a fungal disease and a systemic fungicide would be in order.

Since the tree bounced back well, it is still essentially healthy, so good luck.

Cheers

Kunzea