Landscape Pests

Sharon J. Collman and Michael R. Bush
Revised: 
March 2017

Includes management options for commercial and home use.

In all cases, follow the instructions on the pesticide label. The PNW Insect Management Handbook has no legal status, whereas the pesticide label is a legal document. Read the product label before making any pesticide applications.

Note: Products are listed in alphabetical order and not in order of preference or superiority of pest control.

In this section

Not all users of the PNW Insect Management Handbook are from the states of Washington, Oregon or Idaho. Every effort has been made to ensure that the active ingredients listed here are currently registered for the host/pest in these three states. While many pesticides are registered in all states, check the resources in your own state to ensure the product is registered and legal for the same uses there.

The pesticides are arranged alphabetically by common name of the ingredient and are not listed in order of preference or superiority of pest control. These products are registered to control the pests listed. However, not all products are registered for all the plants that these pests attack; some products may be phytotoxic to certain plants. Check the label to be certain the product you select is registered for the plant and pest that you plan to treat.

Many insecticides are highly toxic to honeybees, bumblebees and other insect pollinators. Some should not be applied any time during bloom, while many others should be applied only in the early morning hours and/or late in the evening. Avoid spraying insecticides on plants surrounded by blooming flowers or weeds. Always take simple steps like removing (mowing) blooming clover from lawns adjacent to garden areas before applying materials that are hazardous to bees. In all cases, when given the choice, select the least hazardous material when plants in the infested vicinity are in bloom. Avoid using dusts wherever possible as dusts will adhere to the bee hairs (like pollen), so liquid spray formulations are preferred for bee safety. Some pesticides have seemed safe for bees but new research is looking at sublethal effects on pollinators such as failure to produce new queens.

In Washington, it is illegal for homeowners to spray plants (or pests) at heights greater than ten feet. Applications at these heights greatly increase the risk of pesticides drifting into non-target areas such as streams or neighboring yards. Where a pest is located at greater heights, a professional pesticide applicator should be called or a non-pesticide option should be chosen. Check local regulations in your state. For more detailed information on toxicity of pesticides to humans or animals, environmental fate, breakdown products and half-life and other information, consult the Characteristics of Insecticides section in this handbook or the National Pesticide Information Center at http://npic.orst.edu/.

Resources

Books

Chastagner, G.A., Byther, R., Antonelli, A.L., DeAngelis, J. and Landgren. 1997. Christmas Tree Diseases, Insects and Disorders in the Pacific Northwest: Identification and Management. Washington State University Cooperative Extension. 154 pg.

Cranshaw, W. 2004. Garden Insects of North America. Princeton Field Guides.

Furniss, R.L. and V.M. Carolin. 1980. Western Forest Insects. USDA Forest Service, Misc Pub 1339. Goheen, E.M. and E.A. Willhite. 2006. Field Guide to the Common Diseases and Insect Pests of Oregon and Washington Conifers. R6-NR-FID-PR-01-06. ISBN 0-16-076244-8. 325 pp. For sale by the Superintendent of Documents, US Government Printing Office. (866) 512-1800 or http://bookstore.gpo.gov/

Johnson, W.T. and H.H Lyon. (1991). Insects That Feed on Trees and Shrubs. 2nd ed., Cornell University Press.

Websites

Hortsense for homeowners in Washington. Includes diagnostic tools and management recommendations for insects, weeds and diseases— http://hortsense.cahnrs.wsu.edu/Home/HortsenseHome.aspx

Lepidoptera of the Pacific Northwest: Caterpillars and Adults. 2003. Jeffrey C. Miller and Paul Hammond. Forest Health Technology Enterprise Team, U.S. Forest Service, USDA. FHTET-03-11. (Hardcopies available). http://www.fs.fed.us/foresthealth/technology/pdfs/FHTET_03_11.pdf

National Pesticide Information Center (NPIC) has both a website and people trained to answer specific questions about pesticides. Information is available in several languages. See http://npic.orst.edu/ or call 1-800-858-7378.

Pesticide Information Center Online (PICOL) is a database for searching currently registered products in Washington and Oregon. http://cru66.cahe.wsu.edu/LabelTolerance.html

PNW Insect Management Handbook online This publication is also available on line at http://pnwhandbooks.org/insect. The website includes pictures of most pests. (See also: PNW Disease Management Handbook online. http://pnwhandbooks.org/plantdisease).

PNW Moths http://pnwmoths.biol.wwu.edu/browse/ New interactive website features photos and seasonal occurrence of adults and biology information of some of the moths of the Pacific Northwest.

The PNW Nursery IPM website includes many landscape plants. The site includes insects, diseases, weeds, slugs, and other pests with photographs and references. http://oregonstate.edu/dept/nurspest/

Common Landscape Pests

A list of the arthropod pests and pesticides for each landscape plant would be lengthy and repetitive. To conserve space, we have generated a list of common pests that can plague a range of ornamental plants, shrubs, and trees (both deciduous and coniferous) in PNW landscapes. Since this is a subset of plants found in home landscapes, the homeowner and applicator must refer to the pesticide label to determine whether any pesticide product can be legally and safely applied to specific plants in their home landscape.