San Jose scale

Diaspidiotus perniciosus

Description:

The San Jose Scale, scientifically known as Diaspidiotus perniciosus, is a significant pest that affects various fruit trees, including apples, peaches, plums, and other stone fruit trees.

Detailed Appearance:

  • Size: Adult scales are small, measuring about 1.5 to 2 mm (0.06 to 0.08 inches) in diameter.
  • Color: Initially, they appear as tiny, yellowish-brown or grayish-brown scales.
  • Features: Scales have a characteristic circular shape with a raised center.

Life Cycle:

  • Crawler Stage: Mobile crawler larvae disperse and settle on host plants.
  • Nymph Stage: Nymphs feed on plant sap, secreting a waxy covering for protection.
  • Adult Stage: Adult females lose their legs and become sessile, while males develop wings for a short-lived flying stage.

Identification of Crop Infestation:

  • Scale Presence: Look for tiny, raised scales on bark, branches, and fruit surfaces.
  • Plant Damage: Infestations lead to weakened trees, stunted growth, and reduced fruit quality.
  • Honeydew and Sooty Mold: Scales excrete honeydew, fostering the growth of sooty mold on plant surfaces.

Management Strategies:

  • Horticultural Oil Sprays:

    • Apply horticultural oil during the dormant season to suffocate overwintering scales.
    • Follow recommended application rates and timing.

  • Biological Control:

    • Introduce natural enemies such as parasitoid wasps that target scale insects.
    • Encourage predatory beetles and lacewings.

  • Systemic Insecticides:

    • Use systemic insecticides for long-term control, particularly in high-infestation areas.
    • Apply systemic treatments according to recommended guidelines.

  • Pruning:

    • Prune and destroy heavily infested plant parts during the dormant season.
    • Promote good air circulation within the tree canopy.

  • Integrated Pest Management (IPM):

    • Implement a comprehensive IPM program combining cultural, biological, and chemical control strategies.
    • Regularly monitor for scale presence and adjust control measures accordingly.

Note: San Jose Scale management requires a holistic approach, combining various strategies to achieve effective control. Regular monitoring and early intervention are crucial for successful pest management. Always follow recommended guidelines and consult with local agricultural experts for site-specific recommendations.