Master Gardeners In the Garden
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Strategies for dealing with unwanted garden pests
By Jenaleigh Fox
WSU Chelan/Douglas County Master Gardener
A Western predatory mite attacks a European red mite. – Photo by: E. Beers The foundation of the Integrated Pest Management pyramid of decision making is diagnosis and monitoring before determining a course of action. – WSU Extension infographic Jenaleigh Fox – WSU Extension Chelan/Douglas County Master Gardener I am relatively new to gardening, and every year at this time I am astounded by new growth. The garden always takes off in ways I cannot even imagine!
Some of the unimaginable explosions of growth are not always wanted, however. Take, for instance, the egg sac in the porch garden that exploded into baby spiders, ready to explore their new world … starting with the porch railing, moving to the head and shoulders of my husband, and landing on the bright lights of a laptop screen. Definitely not wanted.
My spouse’s first instinct was to find some sort of spray to eliminate the spiders from the porch, and I can’t blame him. The impulse to destroy is, for me, a common first-reaction to the feeling of disgust, but my Master Gardener training gave me the tools to pause, set aside the feeling, and figure out an effective approach to the problem.
Learning how to deal with unwanted pests is an important part of gardening, and, I think, a large part of the fun.
For many years, the prevailing philosophy for dealing with pests was preventative eradication with broad-spectrum pesticides. This kill-all approach to pest control did not work perfectly.
Pests developed resistance to pesticides, beneficial insects died, and, well, we’ve all heard about “Silent Spring,” even if we never read the book. The philosophy that Master Gardeners promote is called Integrated Pest Management (IPM). IPM is a framework that pulls ecological information into the decision-making process, to find effective ways to deal with pests that include considering a mix of cultural, mechanical and chemical control options.
I like to think of IPM as cultivating curiosity in the garden. With IPM, problems in the garden become investigative opportunities to learn more about the plant and insect community you’ve created in your yard.
An interesting problem, from an IPM perspective, came into the Master Gardener Plant and Insect Clinic last year from a client who found foliar damage in their home apple trees. From client-provided photos, Master Gardeners could identify the problem pest: apple rust mites. Luckily, there is a well-known IPM approach to that problem! In the 1950s and 1960s, mites in the orchard had become difficult to control with miticides. Scientists and orchardists discovered that if pesticides were chosen and timed carefully, then predatory mites — bugs that eat the bad bugs — could establish a large enough population to control the problem pests. With successful implementation of an IPM approach to mites, many orchardists in the Pacific Northwest have not had to spray specifically for mites since the 1960s!
So, some foliar damage may not be a big problem after all, because predatory mites are an effective biological control for the damage-causing mites. At the Plant Clinic, we advised our client to ensure the trees had enough water (drought-stressed trees are more susceptible to damage) and to remove broadleaf weeds that provide other habitat for the problem mites (cultural control). Then we explained how to monitor predatory mites and suggested purchasing some to release if they couldn’t find a population established in their trees (biological control). Finally, we provided details on how to monitor for the damage done by the apple rust mites, so the client could make a decision on what sprays to add, or not, to their mandatory yearly backyard fruit tree spray schedule (chemical control).
To learn more about Integrated Pest Management, consider attending a free class on the topic scheduled for 10 a.m. to noon on Saturday, July 18. The class — “Creating a Healthy, Resilient Garden: Let’s Deal with Those Pests!” — is part of the WSU Chelan-Douglas Master Gardener Program’s Third Saturday in the Garden series at the Community Education Garden on the northwest corner of Springwater and Western avenues in Wenatchee.
Of course, you can always learn more about pest management and get all your gardening questions answered by visiting the Plant & Insect Clinic in the Sagebrush Room at the Wenatchee Public Library every Monday from 1 to 4 p.m. or email us at AskaMasterGardener@chelandouglasmg.org.
As for my problem with the porch spiders, I recommended my husband take a shower while I vacuumed up the baby spiders (mechanical control), and I released the contents of the vacuum into the alley. Maybe all those spiders will eat some other bugs I don’t want!
A WSU Chelan and Douglas County Master Gardener column appears weekly in The Wenatchee World. To learn more about your local Master Gardener program, visit bit.ly/wsucdmgprogram or call (509) 667-6540.
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