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What's wrong with my plant? How can I avoid this problem again in the future? These common questions are the first of many to ask when diagnosing tree and shrub problems. While sometimes the cause of plant problems are obvious (i.e., seeing the deer eat your plants), many problems demand a more lengthy investigation. Diagnosing tree and shrub problems is much like putting a puzzle together. Many pieces need to be gathered and brought together before assembling the finished product.
Fortunately, there is a useful guide for assembling the pieces:
Experts agree that it takes practice to diagnose plant problems well. Gathering information about the plant, its problems, and the site requires asking good questions or making good observations. Each diagnostic effort will likely deliver new questions. Remember, there is no one set of good questions to ask, but the following article may be a helpful source for asking diagnostic questions related to trees and shrubs:
When diagnosing tree and shrub problems, it is helpful to begin with an idea of possible problems that could affect the plant. The following resources are good overviews of problems commonly affecting plants in the landscape:
Sometimes the onset of tree and shrub problems happens quickly, and sometimes woody plants decline gradually over weeks, months, or years.
Insects and diseases are living agents that need nutrition so they, too, can live and reproduce. Sometimes tree and shrub problems caused by insect and disease can be avoided or managed by selecting resistant varieties or maintaining a healthy plant. On the other hand, there are times when insects and disease damage trees and shrubs even when we plan to minimize their opportunities.
Trees and shrubs in the landscape often have to tolerate less than ideal conditions, making them more vulnerable to insects and diseases. The reality is that insects and disease do affect woody plants. Understanding how biotic factors affect trees and shrubs, identifying the causal organism(s), and implementing control strategies are essential in managing tree and shrub insect and disease problems in the landscape.
Match tree and shrub insect and disease damage symptoms with the pictures using:
Match tree and shrub disease damage symptoms with pictures and descriptions using:
Identify tree and shrub insect and disease problems, along with their solutions by looking up resources that most closely match your region of the country.
Sometimes insects and disease get all the blame for causing tree and shrub problems, but there are many nonliving, or abiotic, causes of plant problems: high temperatures (sunscald), low temperatures (frost damage), drought, flooding, lack of oxygen, lack of sunlight, hail damage, high winds causing plant damage or dessication, air pollutants, deicing salts, herbicide damage, improper planting depth, mechanical injury due to construction damage, lawn mower, vehicles, and animals.
Because the problems listed above are caused by mechanical, environmental/physical, or chemical factors, they are not spread from affected plants to healthy plants. As such, abiotic problems are often called noninfectious diseases. Despite the fact abiotic factors weaken, stress, or kill plants, they have no means of spreading to unaffected plants.
Many times damage symptoms to plants from abiotic factors may resemble that of insects or infectious diseases. Sometimes biotic factors must be ruled out to assume abiotic factors caused the problem. Other times, careful review of the timing of particular events or conditions present at a site will help conclude that abiotic factors are the cause of the problem.
The following provide useful information for diagnosing abiotic problems of trees and shrubs:
Some of the problems mentioned in the guide above, can be reviewed in further detail through the following:
Also known as SGRs, is a noninfectious disease that can lead to tree health decline and premature death. SGRs are preventable and sometimes manageable. The following article provides answers to how they occur and what you can do to prevent them:
Construction damage is sometimes a cause of decline in trees and often avoidable. See what you can do to prevent or mitigate construction damage: