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in Problem solving
In our garden stands a very beautiful old acacia tree of about 8 metres tall. There is a wound on the trunk (maybe 10 centimetres across and 18 cm high) which has at some time been filled with concrete (no it wasn't us). The tree has been fine for the 8 years or so that we have been here but this spring a trickle of sap came out of the wound, which has left a pool of sap on the ground. It was fine during the summer but after recent heavy rain the same thing happened again.
In a nearby park I have seen trees with wounds which have been filled with expanding foam, (the sort you use for DIY work to fill holes / gaps).
So, does anyone know if I should I clean out the old concrete and the wound and fill it with expanding foam? Do I need to treat the area first? Or should I leave it alone?
I hope someone can help
Acacia gum (sap) is harvested for varius uses and the sap is produced naturally by the tree to heal any wounds so production is perfectly natural - it may be that the wound under the concrete is not perfectly healed or the seal is occasionally broken when the tree moves/grows triggering the tree to produce sap.
Presumably if the tree can survive being regularly deliberately wounded to harvest the sap you don;t need to worry too much, assuming it looks healthy otherwise?
I would be worried about removing the concrete as you may case more damage and expose a wider area to potential infection - you could look in your local yellow pages for a tree surgeon and ask them to come and advise you on the best course of action. They will usually do this free of charge but make sure you get someone professionally qualified - the RHS will also answer individual queries.
Thank you so much for that thoughtful and helpful reply. The tree looks perfectly healthy, so I will leave it for now..