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Gloomy Scale Diagnostic Guide

Melanaspis tenebricosa

Gloomy scale (Melanaspis tenebricosa) is a pest of maples primarily in the Eastern US. It rarely kills trees, but can predispose them to other insects/fungi.

Trees at Risk

Gloomy scale attacks: red maple, silver maple, boxelder, catalpa, elm, hackberry, mulberry, and sycamore.

Boxelder

Elm

Red Maple

Silver Maple

Sycamore

Mulberry

Signs of Damage

  • Stunting and general dieback are the only symptoms.
  • Bark is often dark with mold.
Gloomy Scale Signs

Eric Honeycutt, Bartlett Tree Experts, Bugwood.org

Physical Appearance

  • Dark grey scale covers are most noticeable in August.
  • Scales infest only twigs, branches and bark.
  • In June/July nymphs are visible and will settle on bark and twigs.
Gloomy Scale Signs

photo: Adam Dale

Biology

  • Eggs are laid in June/July.
  • Crawlers emerge June/July/August (eggs hatch in 24-48 hours).
  • Overwinter as mated females.

Treatment Strategy

Gloomy scale is very difficult to manage after populations are established. Early detection is critical for best management of infested trees. Monitor three to four year old twigs for the gray protective covers of this armored scale insect. Heavily infested branches should be pruned and destroyed.

  • Soil Application using Transtect

    Dosage: 1 packet/5 inches DBH
    Timing: Early spring is best for control later that year.
    Re-Treatment: Annually
    Transtect
    Transtect
    $326.00
  • Systemic Bark Spray using Transtect

    Dosage: 6-12 packets per 1 gallon water (1.5 – 2.0 oz per inch DBH)
    Timing: Spring close to crawler emergence
    Re-Treatment: Annually
    Transtect
    Transtect
    $326.00
  • Foliar Spray using Transtect

    Dosage: 1 packet/25 gallons water
    Timing: At crawler emergence beginning late May – early June. 8 weeks after full leaf expansion of red maple
    Re-Treatment: Crawlers emerge over a long period of time. 2-3 sprays may be required from initial activity through Sept
    Transtect
    Transtect
    $326.00
  • Foliar Spray using Distance

    Dosage: 8-12 oz/100 gallons water
    Timing: During summer apply Distance™ + RTSA Hort. Oil™ as crawlers emerge in June/July
    Re-Treatment: Reapply if additional crawlers are noted after 14 days
    Distance
    Distance
    $269.00
  • Foliar Spray using RTSA Horticultural Oil

    Dosage: 0.5-1%/100 gallons water
    Timing: During summer apply Distance™ + RTSA Hort. Oil™ as crawlers emerge in June/July
    Re-Treatment: Reapply if additional crawlers are noted after 14 days
    RTSA Horticultural Oil
    RTSA Horticultural Oil
    $39.00
  • Foliar Spray using Up-Star Gold

    Dosage: 1.7 oz. per 100 gallons water
    Timing: Apply at crawler emergence in June/July
    Up-Star Gold
    Up-Star Gold
    $33.33

Treatment Expectations

Spraying during crawler emergence is required for effective control. Improving the growing conditions and plant health will benefit stressed trees.

A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy forestryimages.org. Use of the images does not imply endorsement of treatments by forestryimages.org

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