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Viburnum – What Is Wrong With My Shrub?

Struggling with Viburnum issues? Learn how to diagnose and tackle common shrub problems like pests, diseases, and environmental stresses effectively.

Viburnum, Viburnum opulus, Cranberrybush

Viburnum: A Versatile Shrub for Most Gardens

Belonging to the Adoxaceae family, viburnum encompasses a rich array of more than 150 flowering shrub species. Native to diverse locales such as North America, Asia, and Europe, these plants lure gardeners with their eye-catching flowers, vibrant foliage, and decorative berries. Their high adaptability makes them a go-to choice for a wide range of garden designs.

Viburnum species show a remarkable variety in growth habits, extending from ground-hugging forms to tall shrubs and even pint-sized trees. Their foliage also varies greatly, from simple, oval leaves to complex, lobed configurations, with evergreen, semi-evergreen, and deciduous options depending on the type and climate.

Usually, viburnum boasts small clusters of aromatic flowers, commonly in pink or white, that bloom in late spring or early summer. These are often followed by ornamental fruits in a spectrum of colors like red, blue, black, and yellow, providing both aesthetic appeal and sustenance for wildlife.

In gardens, viburnums serve multiple roles. They can function as show-stopping focal points, natural hedges, or supporting backdrops for other plants. Their suitability for woodland gardens and waterside landscapes adds to their versatility. Some species offer extra benefits like attracting pollinators or possessing medicinal properties.

Hardy in USDA Zones 2-10, these resilient shrubs can adapt to a broad array of soil types and weather conditions. While generally resistant to pests and diseases, some species may be susceptible to issues such as aphids and viburnum leaf beetle.

Viburnum – Common Problems

Viburnum, while breathtakingly beautiful, are not immune to pest and disease issues. Here’s a list of some of the most common problems that target viburnums, with their associated damages and suggested treatments.

Aphids

  • Symptoms: Small green or black insects on the underside of leaves; sticky honeydew residue leading to sooty mold.
  • Causes: Infestation of aphid pests.
  • Treatment: Use insecticidal soaps, neem oil, or introduce natural predators like ladybugs, lacewings, damsel bugs, or hoverflies.

Root-knot Nematodes

  • Symptoms:  Infested plants often display stunted growth, yellowing, wilting, and reduced yield because the nematodes interfere with the plant’s ability to take up water and nutrients. Root examination reveals the presence of galls or swellings.
  • Cause: Nematode infestation.
  • Treatment:  Soil polarization, beneficial nematodes, Marigold cover crops, soil amendments.

Root Weevils

  • Symptoms: Notched leaves, wilting due to root damage.
  • Cause: Root weevil larvae and adults.
  • Treatment: Soil-applied insecticides, beneficial nematodes for larvae.

Scale Insects

  • Symptoms: Brown or white bumps on leaves and stems; leaf drop.
  • Cause: Scale insects feeding on plant juices.
  • Treatment: Horticultural oils and soaps can suffocate scale insects. Chemical insecticides can effectively control these insects. Introducing natural predators, such as ladybugs, lacewings, soldier beetles, and parasitic wasps, can help.

Spider Mites

  • Symptoms: Yellow stippling on leaves, fine webbing on the plant, and tiny mites.
  • Causes: Infestation of spider mites, especially in hot, dry conditions.
  • Treatment: Avoid overcrowding, introduce natural predators like ladybugs, lacewings, and predatory mites. Use horticultural oil or insecticidal soap.

Thrips

  • Symptoms: Discoloration and stippling on leaves. In severe infestations, leaves may become distorted.
  • Cause: Thrips.
  • Treatment: Insecticidal soap or pyrethroid-based insecticides. Multiple treatments may be required.

Viburnum Leaf Beetle

  • Symptoms: Leaves appear skeletonized, defoliation.
  • Cause: Both larvae and adult leaf beetles feeding.
  • Treatment: Control may involve pruning and destroying infested twigs and using insecticides as a last resort.

Whiteflies

  • Symptoms: Yellowed leaves and sooty mold.
  • Cause: Tiny, white, moth-like insects that suck plant sap and excrete honeydew.
  • Treatment: Remove and destroy infested leaves. Use sticky traps, insecticidal soaps, or garlic oil. Encourage predators such as lacewings and ladybugs.

Algal Leaf Spot

  • Symptoms: Green to brownish spots on leaves.
  • Cause: Algae.
  • Treatment: Copper-based fungicides, improve air circulation.

Anthracnose

  • Symptoms: Dark, sunken lesions on leaves, stems, and flowers. During wet conditions, the spots may expand rapidly, causing premature leaf drop.
  • Cause: Fungal pathogens belonging to the genera Colletotrichum and Gloeosporium
  • Treatment: Remove and discard infected leaves and branches. Apply a fungicide containing chlorothalonil or copper-based compounds. Ensure good air circulation through pruning and proper spacing.

Armillaria Root Rot (Honey Fungus)

  • Symptoms: Yellowing, wilting, and premature leaf drop. Mushrooms may grow at the base.
  • Cause: Various species of fungi in the Armillaria genus.
  • Treatment: No effective chemical treatment. Remove and replace infected plants and soil.

Bacterial Leaf Spot

  • Symptoms: Dark, water-soaked spots appear on the leaves. As the disease progresses, these spots may turn necrotic with a yellow halo.
  • Cause: Caused by various bacteria, often exacerbated by high humidity and moisture.
  • Treatment: Remove infected leaves. Ensure proper plant spacing. Avoid overhead watering. Apply copper-based fungicides, though prevention is more effective than treatment.

Botryosphaeria Canker and Dieback

  • Symptoms: Cankers on stems, dieback of shoots.
  • Cause: Fungal infection.
  • Treatment: Prune out and dispose of infected branches. Improving air circulation and reducing plant stress through proper watering and fertilization can also help manage this disease.

Crown Gall

  • Symptoms: Tumor-like growths on roots or base.
  • Cause: Bacterial infection.
  • Treatment: Remove and destroy infected plants; sterilize tools.

Downy Mildew

  • Symptoms: Yellow patches on top, purple-gray mold beneath leaves.
  • Cause: Fungus-like organism.
  • Treatment: Fungicides, lower humidity.

Fungal Leaf Spot

  • Symptoms: Dark brown or black spots with a yellow halo on the leaves. Severe infections can lead to leaf drop.
  • Cause: Various species of fungi, including but not limited to Alternaria, Cercospora, and Septoria.
  • Treatment: Remove and dispose of affected leaves. Apply fungicides containing chlorothalonil or mancozeb. Increase air circulation and avoid overhead watering to reduce leaf wetness.

Powdery Mildew

  • Symptoms: White, powdery substance on leaves.
  • Cause: Fungal infection, especially in humid conditions.
  • Treatment: Fungicides, improve air circulation.

Verticillium Wilt

  • Symptoms: Yellowing, wilting, and dieback starting usually on one side of the plant.
  • Cause: Soilborne fungi, primarily Verticillium dahliae and Verticillium albo-atrum.
  • Treatment: No effective chemical treatment. Prune out affected branches and improve drainage.

Guide Information

Hardiness 2 - 10
Plant Type Shrubs, Trees
Plant Family Adoxaceae
Genus Viburnum
Exposure Full Sun, Partial Sun, Shade
Season of Interest Spring (Early, Mid, Late)
Summer (Early, Mid, Late)
Fall
Winter
Height 2' - 30'
(60cm - 9.1m)
Spread 2' - 12'
(60cm - 3.7m)
Maintenance Low
Water Needs Average
Soil Type Chalk, Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Well-Drained
Characteristics Showy, Fruit & Berries, Fragrant
Tolerance Deer
Attracts Bees, Butterflies, Birds
Landscaping Ideas Hedges And Screens, Beds And Borders, Wall-Side Borders
Garden Styles City and Courtyard, Coastal Garden, Informal and Cottage, Prairie and Meadow, Traditional Garden
Compare All Viburnum
Compare Now
Guides with
Viburnum
While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.

Guide Information

Hardiness 2 - 10
Plant Type Shrubs, Trees
Plant Family Adoxaceae
Genus Viburnum
Exposure Full Sun, Partial Sun, Shade
Season of Interest Spring (Early, Mid, Late)
Summer (Early, Mid, Late)
Fall
Winter
Height 2' - 30'
(60cm - 9.1m)
Spread 2' - 12'
(60cm - 3.7m)
Maintenance Low
Water Needs Average
Soil Type Chalk, Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Well-Drained
Characteristics Showy, Fruit & Berries, Fragrant
Tolerance Deer
Attracts Bees, Butterflies, Birds
Landscaping Ideas Hedges And Screens, Beds And Borders, Wall-Side Borders
Garden Styles City and Courtyard, Coastal Garden, Informal and Cottage, Prairie and Meadow, Traditional Garden
Compare All Viburnum
Compare Now
Guides with
Viburnum

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