Mussel scale

Lepidosaphes ulmi

Overview:

Lepidosaphes ulmi, commonly known as the European Fruit Lecanium Scale or Elm Scale, is a species of scale insect that can be a significant pest on various fruit trees, ornamental trees, and other woody plants. These sap-feeding insects can cause damage by weakening the host plant and facilitating the growth of sooty mold.

Detailed Appearance:

  • Adult female scales are small and usually oval-shaped, with a waxy covering.
  • The color can vary but often includes shades of brown, gray, or black.
  • Males are smaller and more elongated, with wings, and they go through a brief mobile phase during their life cycle.

Life Cycle:

  • The life cycle includes egg, nymph, and adult stages.
  • Female scales produce eggs beneath their protective covering.
  • Nymphs hatch and go through several molts, gradually increasing in size.
  • Adult females remain attached to the plant, while males develop wings for a short-lived mobile phase.
  • Males mate with females, and the cycle continues.

Identification of Crop Infestation:

  • Presence of small, round or oval-shaped scales on branches, twigs, or leaves.
  • Sooty mold growth on plant surfaces due to the excretion of honeydew by the scales.
  • Weakening of the host plant, visible as stunted growth, leaf yellowing, or twig dieback.

Management Strategies:

  • Cultural Controls:

    • Prune and remove heavily infested branches or twigs.
    • Improve plant vigor through proper watering, fertilization, and overall plant care.

  • Biological Controls:

    • Encourage natural predators such as ladybugs, lacewings, and predatory beetles.
    • Parasitic wasps are also effective in controlling scale populations.

  • Horticultural Oil:

    • Apply horticultural oil during the dormant season to suffocate overwintering scales.
    • This treatment is often effective against the more vulnerable nymphs.

  • Systemic Insecticides:

    • Systemic insecticides, applied to the soil or injected into the trunk, can provide long-term control.
    • These insecticides are absorbed by the plant and ingested by the scales.

  • Biological Fungicides:

    • Use biological fungicides to control sooty mold associated with scale infestations.
    • These products can help manage the secondary issue caused by honeydew excretion.