Tree Care and Maintenance
Seasonal Tree Care Tips: Fall 2019
Insects and Diseases
Images courtesy of: Christine Buhl, Oregon Department of Forestry, Bugwood.org
Signs of sequoia pitch moth (Synanthedon sequoiae) on ponderosa pine.
Insect infestations and pathogen infections can threaten the health of your trees. Knowing what tree species you have can help you understand what types of insects and diseases it is susceptible to, and with proper care and maintenance you can manage to prevent problems before they start. Becoming familiar with what is normal for your trees can help you recognize abnormalities early on so that you can take action before it’s too late.
If you recognize abnormalities, the next step is to identify the symptoms (e.g., discolored foliage or top dieback) and look for signs (e.g., insect bore holes or mushrooms). Abiotic problems (caused by non-living organisms, e.g. drought stress or sunscald) generally follow a pattern or uniform display, whereas biotic problems (caused by living organisms, e.g. pests and pathogens) show symptoms in a more scattered or random display throughout the tree or groups of trees. Consider contacting a certified arborist who specializes in plant health care to help diagnose the problem. Once the problem is positively identified, a treatment protocol may be selected. As in the medical field, “treatment without diagnosis is malpractice.”
Not all insect and disease problems have a cure or are necessarily life-threatening. In fact, a variety of common issues are more aesthetic than detrimental, such as alder flea beetle which can skeletonize leaves, or sequoia pitch moth which is commonly mis-diagnosed as bark beetle. Still, your tree may last for many more decades with pruning, systemic injections or cultural practices to manage plant health by optimizing site conditions (e.g., reducing soil compaction and improving soil health, mulching and supplemental watering).
Visit these sites to learn more about managing your trees to prevent and treat insects and diseases:
Insect and Disease Problems, an International Society of Arboriculture Brochure
Plant Health Care, an International Society of Arboriculture Brochure
Pacific Northwest Insect Management Handbook, a Pacific Northwest Extension Publication
Pacific Northwest Plant Disease Management Handbook, a Pacific Northwest Extension Publication
Common Tree Diseases and Pests, City of Portland Webpage
Alder flea beetle, Oregon State University Extension Fact Sheet
Sequoia pitch moth, University of California Integrated Pest Management Pest Notes
Please check back for more seasonal tree care and maintenance advice!
Summer 2019: Drought Stress Revisited
Spring 2019: Trees and Construction
Winter 2019: Topped Tree
Fall 2018: Autumn Leaves
Summer 2018: Emerald Ash Borer
Spring 2018: Pruning Young Trees
Winter 2017: Tree Related Storm Damage
Fall 2017: New Tree Selection and Planting
Summer 2017: Trees and Turfgrasses
Spring 2017: English Ivy Removal
Winter 2017: Recognizing Tree Risk
Summer 2016: Drought Stress
Fall 2016: Preparing Trees for Winter
Additional Tree Care Resources:
|National Arbor Day Foundation||The Morton Arboretum|
|Oregon Department of Forestry||Tree Care Info|
|ISA Find an Arborist||Oregon Community Trees|
|Oregon Department of Forestry||Alliance for Community Trees|
Right Tree in the Right Place
Use this handy guide for assistance in choosing the right species of tree based on the constraints of a site, such as overhead wires, narrow plant strips, and proximity to structures.
"Right Tree Right Place" - helpful information such as "Use this guide for assistance in choosing the right species of tree based on the constraints of a site, such as overhead wires, narrow plant strips, and proximity to structures."
"Master Plant List" - a guide to the plants that are acceptable for mitigation requirements in Lake Oswego.