Identify plant problems
- Before you can recognize or prevent a problem, become familiar with your plants, their growth habits, and the necessary conditions for good growth. Know what your plants should look like at certain times of the year. Are they growing normally? For example, Pine trees have fall color and interior needles turn yellow and fall off leading folks to assume that the tree has a disease or other problem.
- Monitor Plants - Regular inspections of your garden and plants will catch most problems before they get out of hand. Examine all plants carefully including leaf undersides where pests or disease symptoms are often observed. Most problems are noticed when symptoms are advanced (making pest or disease management more difficult), often the case with bagworms that cause extensive damage on evergreens.
- The vast majority of plant issues are not caused by diseases or insects. Problems and death of a plant may be caused by one or several factors known as abiotic problems. Some examples are poor soil drainage, changes in climate, too much or too little water, extreme weather from recent or previous years, air pollution, herbicide drift, planted too deeply, or too much mulch piled up on the trunk.
- Trees and shrubs that decline or die within about 2 years or so after being planted most likely are suffering from abiotic problems. But they can also succumb after a longer period of time.
Steps to diagnosing a plant problem
The ability to accurately diagnose a wide range of plant problems can be developed over time by patient observation and consulting on reliable reference materials. Timely diagnosis of plant problems can help you keep your landscape and gardens beautiful and productive. It can also prevent expensive removal and replacement of damaged plants.
How to begin
- Keep an open mind. Do not jump to conclusions.
- Avoid assigning “guilt by association”. The insect, animal, or disease observed may not be the cause of the problem or the symptoms. Sometimes they will take advantage of the damage or declining plant.
- A “history-taking” of the problem plant is very useful. Extreme weather (drought, unusually hot or cold temperatures, excess rain amounts etc…) , site alteration, grade changes, fertilizer, pesticide and herbicide use, cultural practices, etc. all influence a plant’s relative health over time. Once mature trees begin to decline, there is often no way to reverse the process. Leyland cypress and oaks are common examples of plants which are difficult to rejuvenate after decline symptoms begin.
- Consider all the factors that influence the plant’s growth and health, including how the plant is being taken care of.
- Know what your plant should look like. Knowledge of general growth rates, leaf size and coloration may help alert you to early signs of trouble. Take the time to look under leaves, and when possible at the roots, for potential causal factors.
- The symptom may indicate a problem in a different part of the plant. For example, leaf yellowing and scorching may be caused by root damage.
- There is a great variation in the expected life-span of landscape plants. All plants go through periods of growth, maturity, and decline. Plants grown in urban conditions generally have shorter lives than those grown in natural areas. One example is ornamental cherry trees, they have an average lifespan of only 20-25 years in Maryland.
- Many pests and diseases are plant or host-specific. Symptoms affecting more than one plant species may indicate cultural and environmental problems (abiotic-not related to insects or diseases).
Know where to go for help. You can send questions and digital photos to our Ask Extension Service. Or during the growing season have your questions answered by a Maryland Master Gardener at an Ask a Master Gardener Clinic. Plant clinic locations and times are typically noted on your local county MG website.