Do I need to spray and with what? The enlarged image of the flower may help you to be able to tell me which Eucalypt it is? Many thanks
Thank you for the photo. It is beautiful. I think this is Eucalyptus leucoxylon var macrocarpa 'Rosea'. It could be the black mould present is Sooty Mould which is a result of a sap sucking insect being present and producing honeydew. It is difficult to control these sap suckers when the tree is so large. The best thing to do is to keep the tree healthy, as you are obviously doing. Apply a slow release fertiliser such as Dynamic Lifter Organic Plant Food twice a year, in spring and autumn. Borers can also be a problem for Eucalypts. They burrow into the cambian area of the tree interrupting the flow of nutrients. You usually know they are present as the bark becomes moist and soft and gum will exude from that area. Again there is not a lot you can do to control this pest. Keeing the tree healthy will certainly help it to survive the attack. I am sure your tree will be okay. If it shows signs of decline, it would then be a good idea to consult an aborist, who would be able to give ongoing advice.
Answered: 26 Jun, 2015