Hi there I am in NEW ZEALAND my avocado trees are in flower but the leaves are turning yellow. What should I feed them. It is springtime here.
Outside United States
Here is a link to a list of potential avocado plant problems. Without seeing a photo and more details, it is difficult to say what is causing the yellowing.
If it is OLDER leaves (and new leaves are green and healthy), it COULD be a nitrogen deficiency. If the yellowing leaves are the NEWEST leaves, then it could be an iron or zinc deficiency. Also, excess watering (very wet soil) can cause leaf yellowing and drop.
Sorry that I can't be more helpful, but the amount of information (and no pics) limits my ability to provide a good diagnosis.
Let me know if you have additional questions or can provide more information.