Insects and Diseases

Insects and diseases can threaten plant health, so any abnormal damage or growth patterns should be examined as soon as they are spotted. 

Why are insects and diseases coming to my tree?

Plants require sufficient light, nutrition, and space to be healthy and happy. If any one of those is insufficient, this can cause the plant to become stressed. Most plants will adjust their growth to try to deal with these stresses, but, if it becomes too much for them, it can lead to disease and pest problems.

I’ve noticed something going on with my tree. What do I do?

The easiest first step is to do a thorough examination. Consider the following while you are doing your examination.

• First and foremost, correctly ID the plant. There are many insects and diseases that only infect specific plants. Treatment without confirming ID can be ineffective or harmful.
• Examine the current state and history of your landscape as well as your neighbors’ landscapes. Diseases and pests usually take a long time to spread. If the area is affected quickly and without warning, it is likely physical or chemical damage. 
• Examine the roots. Brown roots can indicate dry soil or chemical issues, while black roots can indicate wet soil or pests that attack roots.
• Examine the trunk and branches for any wounds that could provide entrances for diseases or pests. Large wounds may indicate a potentially hazardous tree. 
• Examine the leaves for appearance and positioning. Leaf damage by itself may not be good enough to identify the disease or pest affecting them. 
• Compare the patterns of damage or appearance. If you have the same plant on or near the site, see if they are both affected. Uniform damage over a large area indicates physical or chemical injury, while non-uniform damage indicates pests or disease. 

If at any point you have any doubt while doing the above steps, please contact an ISA-certified arborist to examine your tree(s). 

What does insect damage look like on a tree?

Insects are typically divided by their method of feeding as this indicates what damage they do in the landscape. Chewing insects will usually eat uneven or broken margins on leaves, flowers, buds, roots, and twigs. They can also skeletonize plant parts or leave long winding paths from leaf miners. 

Sucking insects insert their proboscis (mouth) into plant tissues and feed on the juices. This often causes leaf spots, discoloration, wilting, drooping, or general lack of vitality. These insects also often leave droppings or honeydew behind. 

Boring insects will feed beneath the bark of a tree as larvae. The adults of the species can eat the leaves, and freshly hatched larvae can affect twigs or branches. The tree will usually have holes from the insects entering or exiting the plant.

Keep in mind that most insects in the landscape are beneficial by acting as pollinators or predators to other harmful pests. Killing all of the insects in your landscape can be a detriment to plant health.

What does disease look like on a tree?

Disease requires a pathogen, a susceptible plant to the pathogen, and a suitable environment for the disease to develop. If a plant does not have all three of the requirements, then something else is causing the damage. Some examples of diseases are fungi, viruses, bacteria, and other microorganisms. Diseases can have similar symptoms to physical, chemical, and insect damage, so it is best to make sure the damage is caused by disease before treating it.

How do I treat my tree?

Treatment methods depend on what insect or disease you are dealing with and to what extent the problem has become for the plant. Feel free to reach out to our team of ISA-certified arborists if you have any doubt about the problem or the treatment. They will help you diagnose the problem and help you select a treatment or provide you with a free estimate for treatment.