Let’s Talk About IPM – Integrated Pest Management
By Deborah Smeltzer, Skagit County WSU Extension Master Gardener
Deborah Smeltzer
You are not sure what is wrong with your plant. You are fairly certain it does not look normal and is not growing as it should. You ask, “Am I watering it enough? Am I watering it too much? Does it have a disease? Is some kind of pest causing damage? If so, what should I do? Is there a pesticide that would solve this problem?”
Many of us who garden today would like to create a climate-resilient garden by optimizing soil health, managing our plant selection, determining the best methods for how and when we water, and knowing when it is appropriate and safe to use chemicals. One of the first steps to enhancing sustainability in our gardens is to understand the principles and strategies of Integrated Pest Management, or IPM.
Definition of IPM
“Integrated pest management is an environmentally friendly and common-sense approach to managing insects, diseases, weeds, and other pests of landscapes and gardens by using all the various tools available to gardeners, starting with their skills of observation.”1
IPM helps gardeners to undertake a variety of control methods when needed. These include prevention and cultural, mechanical, biological, and chemical methods. Thoughtful choice of the tools in this toolbox helps us to optimize the health of the plant and the sustainability of our garden. Think about pest control as addressing not just herbivore pests such as insects, slugs, and vertebrates, but also weeds and diseases. Weeds outcompete plants for nutrients. Preventing the presence of weeds or removing them when they are small is a great example of IPM. Incorporating IPM into our garden management is a way to apply a more holistic approach to solving our plant problems.
When we train new master gardener volunteers, we talk about IPM as a common sense approach that uses science, plant health, our skills, patience, and tolerance to manage plant problems.2 We know that if we can better understand the biology of the pest, we can make better decisions about how and when to manage our activities to address pest problems.
Please remember that happy, healthy plants are much less likely to need pest control!
How IPM Contributes to Plant Health Care
IPM is one component of a holistic system of plant health care that allows us to focus on healthy landscapes by being observant about our plants’ cultural needs, the likely pest problems they might encounter, and environmental problems that might be common in their microenvironment. By frequently monitoring our garden, we can be in a better position to observe those conditions that allow our plants to thrive or that might cause problems. Monitoring allows us to be on the lookout for emerging problems before they become too severe to be solved.
Gardeners who take the time and effort to understand the interplay between cultural practices, soil conditions, and growth requirements for specific plants will be in a better position to minimize the impact of adverse environmental conditions.
It is very important to know the garden’s ecosystem to connect the dots between cause and effect. Routine observations help to quickly address factors such as pests, disease, or weather-related damage that could affect our healthy plants. Also, we need to be sure to have a proper diagnosis of the plant problem BEFORE we decide on which IPM solution will be most effective. A successful outcome of our IPM approach will be the reduction of pest populations, not complete eradication.
One of the goals of IPM is to reduce pesticide usage in our landscapes. By looking at the whole picture of what is happening in our garden, we have the opportunity to reduce the use of pesticides by 50 to 90 percent and create a more sustainable environment.3 Many home gardeners use more chemicals than agricultural operations. By tolerating some damage, we can reduce the overuse of chemicals and ensure less toxicity to our environment.
IPM Strategies
Each form of control needs to be chosen at the proper time. This is another reason that monitoring is so important. There is no reason to undertake control if the pest has not yet emerged in the garden or is no longer present. The observant gardener will know when an insect pest’s eggs hatch relative to the timing of leaf emergence of that insect’s favorite host plant. Covering cruciferous crops with row covers after the cabbage moth has visited is too late to prevent damage. Many fungal diseases target blossoms or new growth and need to be addressed during a discrete seasonal window.
Mechanical and Physical Control can be used to make the environment unfavorable for the pest to exist. This might include devices that block pest access to plants, such as physical barriers or tools for pest removal. Examples include:
- Fly swatter
- Netting – Reemay® for insect exclusion or bird netting
- Weeding (before seedheads appear!)
- Traps – for insects or rodents
- Disposal of slugs and snails early in the season
- Installation of wire mesh at the bottom of raised beds to deter voles
Cultural Control means the manipulation of the plant or the environment to change the conditions and reduce the likelihood of pest problems. It requires knowledge of the biology and behavior of both the plant and the pest. This approach includes the philosophy of “Right Plant, Right Place,” which refers to selecting plants appropriate for the area where they are planted to increase growing success and reduce plant stress. Plants that are stressed are more susceptible to diseases and invite pests. Some examples of cultural control are:
- Selecting plants with resistance to common pests
- Proper planting techniques and dates
- Crop rotation
- Pruning
- Site condition management, such as the use of water and mulch
This Month in Your Garden
- Early to Mid-August -
- Fertilize roses once more before before allowing them to go dormant.
- Harvest garlic when the lower 1/3 of leaves turn brown.
- August - September -
- Prune bamboo culms to thin your bamboo. Prune older (without sheaths), leaning, or damaged culms and cut them close to the ground. Prune any culms encroaching into an undesired area, and don’t forget root pruning to contain your grove.
- Deadhead perennials that self-seed, such as calla lilies, Shasta daisy, and crocosmia to prevent propagation.
- Harvest onions and shallots when the necks become soft and the tops fall over.
Biological Control is when other living organisms are used to control pest organisms. A few examples are:
- Release of lady beetles to control aphids
- Using herbivores like goats to control weeds
Chemical Control is when pesticides are used to control pests and should be the control method chosen only when other options are not available. Pesticides are regulated and have detailed labels and instructions that need to be followed. Be sure to choose a chemical that is the least hazardous to the environment. Several key factors are important before choosing a chemical control. In most cases, the pest needs to be active. In addition, pollinators that are vital to plant health and food production need to be protected, as well as their water sources. Many insecticides will also harm beneficial insects, so it is key to READ THE LABEL and also be willing to tolerate some damage.
In summary, IPM is a science-based approach to gardening that enhances the sustainability of our gardens. “The approach is straightforward: identify the pest, assess its severity, determine its life stage, consider the site’s conditions, weigh risks and benefits, select a management strategy, and take action (or choose not to) with safety and environmental responsibility in mind.”5 Frequent observation and monitoring, along with concise diagnosis of plant problems and selecting appropriate preventive and control measures, can help us achieve a healthy, happy planet.
Know & Grow: The Allure of Dahlias
with Steve Lloyd
Free, no registration required
Come hear local expert, Steve Lloyd, the “Dahlia Doctor,” talk about mid- and late-season care, plus the winter care options for these stop-you-in-your-tracks plants.
Tuesday, August 19, 2025
1 pm - 2:30 pm
NWREC Sakuma Auditorium
16650 State Highway 536, Mount Vernon
New Certificate Programs in Skagit County
Washington Gardener Certificate Program is designed to provide comprehensive research-based horticulture and environmental stewardship education. This option is ideal for individuals seeking to enhance their gardening skills without the commitment of volunteering. This self-paced, online-only course provides a certificate upon successful completion. Registration deadline: Sept. 30, 2025. For more information, go to https://skagitmg.org/home/green-school/
Climate Stewards Certificate Program is a collaborative, multi-institutional group working across disciplines to promote climate awareness, education, and action. Registration deadline: Sept. 16, 2025. Learn more about the program: https://extension.wsu.edu/skagit/skagit-climate-stewards/
REFERENCES AND RESOURCES:
- Pacific Northwest Gardener’s Handbook. 2025. WSU Extension, Master Gardener Program. Chapter 21 [quotation is on page 21-3] Available at https://pubs.extension.wsu.edu/product/pacific-northwest-gardeners-handbook-growing-for-the-future/
- Pautzke, K. 2025. Skagit County WSU Extension Master Gardener Training 2025, IPM slides.
- Holmes, J.J. and Davidson,J.A. 1984. Integrated Pest Management for Arborists: Implementation of a Pilot Program. Journal of Arboriculture 10:65–70.
- National Pesticide Information Center (NPIC) website. https://www.npic.orst.edu/pest/ipm.html
- Collman, S. 2025. Integrated Pest Management (IPM) is a Decision You Make. Summary of 2025 Advanced Education Conference lecture hosted by Master Gardener Foundation of Washington State.
ABOUT THE AUTHOR:
Deborah Smeltzer is a Skagit County WSU Extension Master Gardener (EMG), Class of 2012. She currently serves on the Skagit County Master Gardener Foundation board and as chair of the Skagit County WSU EMG Program Training Team. In 2020, Deborah was named Washington State Master Gardener of the Year by the Master Gardener Foundation of Washington State.
Questions about home gardening or becoming a master gardener may be directed to Skagit County WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the website: www.skagit.wsu.edu/mg
Washington State University Extension helps people develop leadership skills and use research-based knowledge to improve economic status and quality of life. Cooperating agencies: Washington State University, US Department of Agriculture, and Skagit County. Extension programs and policies are available to all without discrimination. To request disability accommodations contact us at least ten days in advance.
Thank you!
Could you speak about vole management. They’re decimating our peas, beets, green beans, carrots,ect. They’re starting on the Winter squash . Ugh… We have these solar powered beeping gizmos that are inserted about a foot into the ground. They run right by them.
We’ve tried plaster of Paris with cornmeal and car exhaust in their tunnels. Can you tell, they drive us nuts? Haven’t tried the castor oil, dawn dishwashing mix yet. I’m afraid it would taint the veggies. What’s your advice? Thanks in advance.
Ugh, I’m sure the voles are frustrating! Here’s a link a fact sheet prepared by WSU on managing vole in your garden. https://wpcdn.web.wsu.edu/wp-ecommerce/uploads/sites/2/product-4291-sku-FS094E.pdf. I hope this helps!