Pest & Disease
Rhododendron Lace Bug
The pest most gardeners here call rhododendron lace bug is actually the azalea lace bug. How to tell the three species apart and time your response.
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Identification, lifecycle, and management strategies for common pests and diseases in our region.
Pest & Disease
Balsam Woolly Adelgid: The Silent Threat to Your Landscape Firs
Balsam woolly adelgid has been in the Pacific Northwest since 1930, quietly removing grand fir from lowland landscapes. Most gardeners have never heard of it. If you have a true fir, you should know what it is and what to look for.
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Pest & Disease
Spring Vegetable Pest and Disease Prevention: Diagnosing What Is Killing Your Seedlings
Three problems kill spring vegetable seedlings in the Puget Sound lowlands: damping off, cutworms, and slugs. Each leaves a different signature and demands a different fix. Learn to read the stem, the soil, and the damage pattern before you reach for a product.
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Pest & Disease
Leaf Spot Diseases: When to Worry and What to Do About It
Most leaf spots on established plants are cosmetic. Learn to tell the difference between harmless spotting and the few leaf spot diseases that actually threaten plant health in the Puget Sound lowlands.
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Pest & Disease
Spring Slug and Snail Management: Protecting Your Garden in the Wet Season
Identify the three slug species that matter in the Puget Sound lowlands, understand why national advice fails here, and build a seasonal management plan anchored by fall baiting and iron phosphate.
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Pest & Disease
Fire Blight Bloom Window: Reading the Risk and Knowing When to Act
How to read fire blight infection risk during bloom using the CougarBlight model, when to apply Bacillus subtilis, and how to respond to shoot blight with proper pruning technique.
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Pest & Disease
Emerald Ash Borer: What Puget Sound Needs to Know Before It Arrives
In July 2025, a private arborist in Portland noticed stress symptoms on a green ash near a swimming pool parking lot.The crown was thinning from the top.
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Pest & Disease
Codling Moth: Protecting Your Harvest From the Inside Out
You cut into an apple from your backyard tree and find a brown, frass-filled tunnel running straight to the core.
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Pest & Disease
Tent Caterpillars: What the Webs Mean and When to Act
Sometime in late April or early May, you walk outside and notice thick, cottony webs bunched in the branch forks of your cherry tree or crabapple.
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Pest & Disease
Gray Mold: The Disease Your Climate Was Designed For
You find it on a Monday morning in May. The strawberry you were planning to pick tomorrow is covered in a gray, dusty fur.
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Pest & Disease
Apple Scab: The Disease You Can Plan Against
You notice it in May.Olive-green spots on the upper surface of your apple leaves, each one the size of a pencil eraser, with edges that look a little smoky.
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Pest & Disease
Bronze Birch Borer: Why Your Birch Is Dying from the Top
You planted a European white birch because you wanted that white bark against a dark fence, or because the developer put one in twenty years ago and you inherited it.
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Pest & Disease
Scale Insects: Managing the Armored and Soft Types
You notice the sticky residue first.Something is dripping onto your car, your patio furniture, the hosta leaves underneath the dogwood.
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Pest & Disease
Phytophthora Root Rot: The Water Mold That Loves Your Soil
Why our wet winters create perfect conditions for Phytophthora, and how to protect your landscape.
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Pest & Disease
Anthracnose: Two Diseases, One Name
Learn the difference between cosmetic leaf spot anthracnose and destructive dogwood canker disease. Regional strategy for the Pacific Northwest.
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Pest & Disease
Aphids: Why Spraying Is Usually the Wrong First Move
Aphids are everywhere in our region's gardens. The best response is usually no response at all. Here is how to tell when that changes.
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Pest & Disease
Armillaria Root Rot: Prevention in a Fungus-Loaded Landscape
Armillaria root rot is a fungal disease that weakens tree health through decay of roots and the base. Learn identification, prevention, and management.
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Pest & Disease
Eriophyid Mites: The Invisible Pest Behind Galls, Blisters,
Those strange galls on your maple leaves and blistered pear foliage are caused by mites too small to see. Most of the time, the plant does not care.
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Pest & Disease
Fire Blight vs. Pseudomonas: Diagnosing Spring Shoot Blight
Most spring shoot blight on pears and apples in the Pacific Northwest is Pseudomonas, not fire blight. Learn to distinguish the two and manage them correctly.
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Pest & Disease
Leafminers: The Pest You Can Almost Always Ignore
Those winding trails and blotches inside your leaves look alarming. On most landscape plants, leafminers are cosmetic damage that requires no treatment.
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Pest & Disease
Root Weevil: The Night Shift Pest in Every Western
Root weevils are the most common landscape pest in this region. The notched leaves are cosmetic. The larvae eating your roots are not. Here is what to do about both.
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Pest & Disease
Spider Mites: The Pest That Thrives When Your Plants Are
Spider mites explode in hot, dry conditions. In this region, that means July and August are your risk window. Here is how to spot them early and what actually works.
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Pest & Disease
Verticillium Wilt: The Soil Disease That Outlasts Everything
You notice it on a Tuesday in July.One side of your [Japanese maple](/guides/japanese-maple/) wilts while the other side looks fine.
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Pest & Disease
Black Spot on Kelsey's Dogwood: Diagnose, Treat, Prevent
Kelsey's Dogwood Black Spot is a fungal disease affecting dogwoods in humid maritime climates. Identification, prevention, and treatment are covered.
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Pest & Disease
Dormant Oil Sprays: The Window You Cannot Miss
You're standing in your orchard in mid-March, watching your apple and pear trees prepare to leaf out.
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Pest & Disease
Invasive Plants in the Puget Sound Region: What to Watch
Learn which non-native plant species pose the greatest ecological threat in the Puget Sound lowlands and what properties to avoid when selecting plants.
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Pest & Disease
Powdery Mildew: Why Your Climate Gives You an Advantage
Powdery mildew in the maritime Pacific Northwest behaves differently than national guides assume. Learn why the wet spring sets up the June explosion, which plants need treatment, and how to read the temperature window that triggers it.
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Pest & Disease
Crane Flies: What They Do to Your Lawn
You're looking at your lawn in late February and noticing irregular brown patches.The grass is thin, dead sections are expanding, and you're starting to panic.
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