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  • Home
  • About, Services, Contact
  • Ask Amanda
  • Roses
    • Types of Roses
    • Easy Roses
    • Climbing Roses
    • Portland's Rose Test Garden
    • Rose Insects & Diseases
    • Pruning Roses
    • Rose Sawfly
    • Rose Bloom Balling
  • Pruning Basics 101
    • Pruning Tools
    • Winter Pruning
    • Pruning Grapes
    • Pruning Clematis
    • Prune Your Own Garden Registration
  • Lawn Basics
    • Lawn Reno, Seed & Sod
    • Lawn Maintenance Schedule
    • Spring Lawn Care
    • Moss in Lawns
    • Lawn Alternatives
    • Lawn Grub Control
  • Mulch & Mulching
    • Living Mulches - Groundcovers
  • Propagation
    • Growing Seeds Outdoors
    • Growing Seeds Indoors
    • Taking Cuttings
    • Seed & Plant Catalogues
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    • Soil Building
    • Watering Tips & Techniques
    • Drought Gardening
    • Sheet Mulching, Lasagna Gardening
    • Cover Crops
    • Composting
    • Compost Tea
    • Houseplant Winter Care
    • Hummingbirds in Winter
    • Winterize Your Garden
    • Ponds in Winter
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    • Crop Rotation, Succession & Companion Planting
    • Harvesting
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    • Winter Veggie Gardening
    • Taming Tomatoes
    • Speeding up Tomato Harvest
    • Tomato Tips
    • Saving Tomato Seeds
    • Tomato Troubles
  • Plant Pests 1
    • Plant Pests Part 2 - Controlling Insects
    • Garden Inspections
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    • Dogwood Anthracnose
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    • American Sweetgum
    • Ash (Fraxinus) Trees
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    • Aubretia, Rock Cress
    • Aucuba, Japanese Spotted Laurel
    • Autumn Crocus
    • Bear's Breeches
    • Beautyberry, Callicarpa
    • Black-eyed Susans
    • Bleeding Heart, Lamprocapnos spectabilis
    • Calla Lilies
    • Dahlias
    • Daylily
    • Delphiniums
    • Devil's Walking Stick, Aralia spinosa
    • Dwarf Alberta Spruce
    • Dwarf Burning Bush
    • Fall Asters
    • Flowering Currants
    • Flowering Quince
    • Fritillaria
    • Garden Peonies
    • Garden Phlox
    • Ginkgo biloba
    • Grape-hyacinths
    • Handkerchief or Dove Tree
    • Harry Lauder's Walking Stick
    • Heathers
    • Hellebores, Lenten roses
    • Himalayan Sweet Box
    • Jack-in-the-pulpit, Cobra Lily
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    • Pink Dawn Bodnant Viburnum
    • Poinsettias
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    • Ornamental Kale
    • Peruvian Lily, Alstroemeria
    • Phalaenopsis, Moth Orchids
    • Persian Silk Tree
    • Portuguese Laurel
    • Rose of Sharon
    • Sneezeweed, Helenium
    • Snowberry
    • Snowdrops
    • Star Magnolia
    • Strawberry Tree, Pacific Madrone
    • Stewartia
    • Torch Lily, Kniphofia uvaria
    • Tree Peonies
    • Tuberous Begonias
    • Virginia Creeper
    • Weigela
    • Winterhazel, Corylopsis
    • Winter Camellia, C. sasanqua
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Dogwood Anthracnose

A Deadly Dogwood Disease 

Picture
Dieback
Picture
Infected foliage
Dogwood trees are coveted for their beautiful, full round canopies and white bracted flowers that turn pink as they age. These popular urban trees look good all year round and are well-behaved, however, they do have a weakness: dogwood anthracnose (Discula destructiva). It’s a prevalent and destructive dogwood tree disease that’s a killer.
Picture
Lesions are brown haloed in purple.
Picture
Dieback and infected foliage.
Symptoms: Brown spots first appear on leaves and the flower bracts in the spring. Tan spot on the leaves have purple edges ringed with brown and soon the leaves become distorted.  As the disease progresses all the branches and trunk are affected. Cankers (swollen or sunken brown areas) wrap around stems, cutting off circulation, killing the branch and even tree trunks. Infected stems die back at their tips leaving bare, dead branches.

Prevention: Wet, cold springs, shady locations and lack of air circulations prompt the disease. Plant dogwoods where they will receive good air circulation with no overhead trees, and don’t overcrowd. Locate them in full sun, especially in the morning to quickly evaporate morning dew. Avoid watering late in the day or in the evening and overhead watering.  Avoid high nitrogen fertilizers and prune trees only in summer when it’s dry. Remove any infected foliage from the plant and the ground, especially in autumn. Don’t leave dead branches and foliage on the plant.
Picture
Kousa dogwoods are highly resistant to anthracnose.
Select resistant varieties: The most susceptible dogwoods are indigenous to North America: Eastern flowering dogwood (Cornus florida) and the Pacific dogwood (Cornus nuttalli). The kousa dogwood (Cornus kousa), Appalachian Spring and Stellar Pink dogwood are highly resistant. Moderately resistant types are Celestial, Galaxy, Constellation, Ruth Ellen and Aurora. Inspect plants thoroughly before buying including their branches and trunk.
Picture
Dormant oil/lime sulfur combo offers some control.
Control: Although this disease is difficult to control, dormant oil and lime sulfur is helpful. This combination mix is sold together and must be applied when the tree is dormant, just before budbreak (late January to early February in the Pacific Northwest). Purchase the kit now as it is often not available in stores in the middle of winter. Follow the instructions and don’t forget to spray the ground surrounding the tree. For more information on dormant oil/lime sulfur click on Dormant Oil/Lime Sulfur. Copper fungicides have proven to be effective during the growing season. It is recommended to remove all infected leaves and plant parts from the plant and the ground before spraying.

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Copyright © 2017
  • Home
  • About, Services, Contact
  • Ask Amanda
  • Roses
    • Types of Roses
    • Easy Roses
    • Climbing Roses
    • Portland's Rose Test Garden
    • Rose Insects & Diseases
    • Pruning Roses
    • Rose Sawfly
    • Rose Bloom Balling
  • Pruning Basics 101
    • Pruning Tools
    • Winter Pruning
    • Pruning Grapes
    • Pruning Clematis
    • Prune Your Own Garden Registration
  • Lawn Basics
    • Lawn Reno, Seed & Sod
    • Lawn Maintenance Schedule
    • Spring Lawn Care
    • Moss in Lawns
    • Lawn Alternatives
    • Lawn Grub Control
  • Mulch & Mulching
    • Living Mulches - Groundcovers
  • Propagation
    • Growing Seeds Outdoors
    • Growing Seeds Indoors
    • Taking Cuttings
    • Seed & Plant Catalogues
  • How to Garden Topics
    • Fall Garden Chores
    • Planting Know-How
    • Soil Building
    • Watering Tips & Techniques
    • Drought Gardening
    • Sheet Mulching, Lasagna Gardening
    • Cover Crops
    • Composting
    • Compost Tea
    • Houseplant Winter Care
    • Hummingbirds in Winter
    • Winterize Your Garden
    • Ponds in Winter
  • Growing Food
    • Spring Veggie Gardening
    • Crop Rotation, Succession & Companion Planting
    • Harvesting
    • Growing Potatoes
    • Winter Veggie Gardening
    • Taming Tomatoes
    • Speeding up Tomato Harvest
    • Tomato Tips
    • Saving Tomato Seeds
    • Tomato Troubles
  • Plant Pests 1
    • Plant Pests Part 2 - Controlling Insects
    • Garden Inspections
    • Helping Pollinators
    • Dogwood Anthracnose
    • Viburnum Leaf Beetle
    • Dormant Oil/Lime Sulfur
    • Japanese Beetles
    • Peony Blotch/Measles
    • Slugs & Snails
    • Horsetail, the Weed
    • June Beetle
    • Powdery Mildew
    • Soil Solarization
    • Rhododendron Leaf Spot
    • Plant Rusts
    • Black Knot
  • Container Growing
    • Choosing a Container
  • Feeding Plants 101
    • Fertilizers & Ratios
    • Nutritional Deficiencies & Toxicities
    • Organic Plant Food
  • Plant of the Month
    • Spring Flowering Bulbs
    • Colourful Fall Plants
    • Abelia
    • American Sweetgum
    • Ash (Fraxinus) Trees
    • Astilbes
    • Aubretia, Rock Cress
    • Aucuba, Japanese Spotted Laurel
    • Autumn Crocus
    • Bear's Breeches
    • Beautyberry, Callicarpa
    • Black-eyed Susans
    • Bleeding Heart, Lamprocapnos spectabilis
    • Calla Lilies
    • Dahlias
    • Daylily
    • Delphiniums
    • Devil's Walking Stick, Aralia spinosa
    • Dwarf Alberta Spruce
    • Dwarf Burning Bush
    • Fall Asters
    • Flowering Currants
    • Flowering Quince
    • Fritillaria
    • Garden Peonies
    • Garden Phlox
    • Ginkgo biloba
    • Grape-hyacinths
    • Handkerchief or Dove Tree
    • Harry Lauder's Walking Stick
    • Heathers
    • Hellebores, Lenten roses
    • Himalayan Sweet Box
    • Jack-in-the-pulpit, Cobra Lily
    • Japanese Anemones
    • Japanese Forest Grass
    • Japanese Maples
    • Japanese Skimmia
    • Japanese Spurge
    • Laurustinus viburnum
    • Lavenders
    • Lily-of-the-Valley Shrub, Pieris japonica
    • Mediterranean Spurge
    • Mexican Mock Orange
    • Montana Clematis
    • Mountain Ash
    • Oriental Poppies
    • Oriental Lilies
    • Paperbark Maple
    • Pink Dawn Bodnant Viburnum
    • Poinsettias
    • Oregon Grape Holly
    • Ornamental Kale
    • Peruvian Lily, Alstroemeria
    • Phalaenopsis, Moth Orchids
    • Persian Silk Tree
    • Portuguese Laurel
    • Rose of Sharon
    • Sneezeweed, Helenium
    • Snowberry
    • Snowdrops
    • Star Magnolia
    • Strawberry Tree, Pacific Madrone
    • Stewartia
    • Torch Lily, Kniphofia uvaria
    • Tree Peonies
    • Tuberous Begonias
    • Virginia Creeper
    • Weigela
    • Winterhazel, Corylopsis
    • Winter Camellia, C. sasanqua
    • Wintergreen, Gaultheria procumbens
    • Witch Hazel
    • Wood Anemones
    • Yews
  • Garden Tour Blogs
  • Monthly Flower Arrangements
  • Website Index
  • Subscribe
  • Need Help?