Q.Pittosporums
I live in Sydney Australia and planted several pittosporum trees about 20 years ago. They are mostly healthy even though we are having a hot summer. I keep them watered and give them a slow release pellet feed twice yearly. I have noticed that they all have marks on the trunks with a pale coloured sap leaking from them, but not all the way down the trunks. Is this a sign of a pest or nothing to be concerned about? Thanks. Sandra

Certified GKH Gardening Expert
Though I am not completely familiar with the pests in your area, I would be likely to say that it could be an animal that is damaging them. If possible try and enclose the area in fencing, or even wrap the trunks very lightly individually.
Here is an article for more information on the plant: https://www.gardeningknowhow.com/ornamental/shrubs/pittosporum/growing-japanese-pittosporum.htm