AusBonsai

My olive has rusty spots on trunk and leaves. Does anyone know what it is, how to fix it and how to prevent it?

Thanks







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That is SCALE. Treat it with ecooil or confidor.

Hey mate .
Ive had this issue before on my olives also .
Some eco oil fixed it quick smart ... as to what it is ... will wait for the experts .
I belive it is exactly that , rust . Fungicide and move it to a well ventilated area and sun .
Good luck

Pup would be that expert you were waiting for dibly.

Pup is correct again. That is scale insect and the treatment is also spot on.

Thanks and cause by shade?

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More so not having enough water on the plant and the possibly indicates a stressed plant.

I don't think scale is related to the amount of sun your tree gets but I have noticed they seem more prolific on trees that are not specially healthy so maybe shade could have an indirect affect.
It is an insect - not sure how they travel- that gets on your tree, builds those little protective shields to protect itself and settles down to sucking sap from the tree and making a lot more scale insects. Lots pof scale all sucking sap does weaken the tree so best to deal with them. As well as sucking sap they secrete sugary waste (honeydew) which gets on the foliage and eventually goes mouldy - black sooty mould on the leaves. Ants love honeydew so you will usually find ants on trees with scale. Ants actually look after them and 'farm' the scale. I think they even move some from one tree to another to expand the empire. Maybe that's where yours have come from?

If there's only a few you can scrape them off but when there's lots like this it is easier to spray with an oil based spray. Oil sprays rely on contact with the target so you'll need to spray all surfaces of leaves and trunk. Sometimes ned a follow up spray a few weeks later. If they are coming back, maybe from nearby trees you might need to spray once or twice a year to maintain control

Thanks very much . May explain lack of growth on this olive

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