Correct diagnosis of plant health problems requires a careful examination of the situation.


1. Accurately identify the plant. Because many insects and diseases are plant-specific,
this information can quickly limit the number of suspected diseases and disorders.

2. Look for a pattern of abnormality. It may be helpful to compare the affected plant with other plants on the site, especially those of the same species. Non-uniform damage patterns may indicate insects or diseases. Uniform damage over a large area (perhaps several plant species) usually indicates disorders caused by such factors as physical injury, poor drainage, or weather.

3. Carefully examine the landscape. The number of species affected may also help distinguish between infectious pathogens that are more plant-specific as compared to chemical or environmental factors that affect many different species. Most living pathogens take a relatively long time to spread throughout an area, so if a large percentage of plants become diseased virtually overnight, a pathogen is probably not involved.

4. Examine the roots. Note their color: brown or black roots may signal problems. Brown roots often indicate dry soil conditions or the presence of toxic chemicals. Black roots usually reflect overly wet soil or the presence of root-rotting organisms.

5. Check the trunk and branches. Examine the trunk thoroughly for wounds because they provide entrances for pathogens and wood-rotting organisms. Wounds can be caused by weather, fire, lawnmowers, and rodents, as well as a variety of other environmental and mechanical factors. Large defects may indicate a potential hazard.

6. Note the position and appearance of affected leaves. Dead leaves at the top of the tree are usually the result of environmental or mechanical root stress. Twisted or curled leaves may indicate viral infection, insect feeding, or exposure to herbicides. The size and color of the foliage may tell a great deal about the plants condition. Make note of these and any other abnormalities.