SHURTLEFF, MALCOLM C. 1989. Diagnosing shade tree diseases. Grounds Maintenance 24(6):22, 24, 26, 68, 72.
Learning how to diagnose common diseases will help you maintain healthy trees. Rapid and accurate diagnosis is the first step in the treatment of any disease. Follow these basic steps: 1. Evaluate the overall appearance of an unhealthy tree. When you evaluate problem trees on-site, knowledge of the past history of a tree will help you to determine the true cause or causes of a problem. 2. Look for direct evidence (signs) of the cause. Examine the foliage, twig and branch system, trunk and roots. A weakened tree is much more susceptible to secondary attacks by insects (such as borers) or diseases (like canker, certain wilts, root rots and wood decay). 3. You may need a laboratory examination and/or culturing to confirm your tentative diagnosis.
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