The top leaves of my recently planted Eucalyptus tree (about 6 feet tall) seem to be drying up a bit. A neighbor pointed out that sap from a bigger tree (I think it's called, at least in England, 'Plain' tree) are dropping on the Eucalyptus leaves and that might be the cause. I'm a novice in these matters and would be much obliged to receive your kind guidance as to the probable cause and also how to cure and prevent it.
Tree Sap on Other Plants
Since it's only the top of the eucalyptus showing problems, I wouldn't worry too much. The new growth on branch tips is the most susceptible to stress of any kind. Have you been watering? Always water weekly and thoroughly, a little bit and often is thee worst thing you could do. Get the moisture down deep into the root system.