Help, I have Black marks on the trunks on my olive trees, what do I do?

What is the problem?

Hi Amanda,

Please help, we are based in the Hunter Valley and it appears that where moisture runs through the tree is where the problem is  (see pictures).  It doesn’t look like sooty mould but we had scale and olive lace bug issues.  The trees are in urgent need of care.  What is the black on the trunks and what do I do?  P NSW

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So, what is going on and how do I fix this? 

I have spoken with plant pathologist, Dr Len Tesoriero from DPI NSW and he has the following suggestion:

“There appears to be dead wood running up the stem on one side. This is probably from a wood rotting fungus (Botryosphaeria or even one of the basidiomycetes) although the damage looks to be quite old and it may no longer be active. Again if it’s possible I’d cut the limb off and use copper or lime sulphur on the wound. If the conclusion is that the fungus is no longer active – the tree can sometimes partition infected wood and the fungus may die out – or if it is on the main trunk and it would be difficult to excise then leave it or just treat it with copper or  lime sulphur”

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