Illustrations in full color. Abstarct: "The nursery manager has a basic knowledge of symptoms and a habit of careful observation and can usually diagnose most forest nursery pest problems. The first step in diagnosing a pest problem is recognizing that a problem exists. To do this, the manager must routinely monitor the nursery and learn what healthy seedlings look like under all conditions. Once this healthy standard has been established, the manager (and properly trained personnel) can spot abnormalities. In addition, routine monitoring allows one to catch a problem early, when it is relatively simple and inexpensive to treat and before extensive damage occurs."