Diagnosing plant problems requires a combination of knowledge, experience, and keen observation. Most often it is not simply a case of identifying an insect or disease. Trees that die or decline usually are suffering from combination of stress factors, and insects or diseases are often secondary, attacking the weakened tree. It takes some detective work to piece together all of the clues. Then, arriving at a diagnosis is often only the first step. The important second step is to make appropriate recommendations.